src/mesa/main/viewport.c - platform/external/mesa3d - Git at Google

 /*
  * Mesa 3-D graphics library
  *
  * Copyright (C) 2009  VMware, Inc.  All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included
  * in all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  * OTHER DEALINGS IN THE SOFTWARE.
  */


 /**
  * \file viewport.c
  * glViewport and glDepthRange functions.
  */


 #include "context.h"
 #include "enums.h"
 #include "macros.h"
 #include "mtypes.h"
 #include "viewport.h"

 static void
 clamp_viewport(struct gl_context *ctx, GLfloat *x, GLfloat *y,
                GLfloat *width, GLfloat *height)
 {
    /* clamp width and height to the implementation dependent range */
    *width  = MIN2(*width, (GLfloat) ctx->Const.MaxViewportWidth);
    *height = MIN2(*height, (GLfloat) ctx->Const.MaxViewportHeight);

    /* The GL_ARB_viewport_array spec says:
     *
     *     "The location of the viewport's bottom-left corner, given by (x,y),
     *     are clamped to be within the implementation-dependent viewport
     *     bounds range.  The viewport bounds range [min, max] tuple may be
     *     determined by calling GetFloatv with the symbolic constant
     *     VIEWPORT_BOUNDS_RANGE (see section 6.1)."
     */
    if (_mesa_has_ARB_viewport_array(ctx) ||
        _mesa_has_OES_viewport_array(ctx)) {
       *x = CLAMP(*x,
                  ctx->Const.ViewportBounds.Min, ctx->Const.ViewportBounds.Max);
       *y = CLAMP(*y,
                  ctx->Const.ViewportBounds.Min, ctx->Const.ViewportBounds.Max);
    }
 }

 static void
 set_viewport_no_notify(struct gl_context *ctx, unsigned idx,
                        GLfloat x, GLfloat y,
                        GLfloat width, GLfloat height)
 {
    if (ctx->ViewportArray[idx].X == x &&
        ctx->ViewportArray[idx].Width == width &&
        ctx->ViewportArray[idx].Y == y &&
        ctx->ViewportArray[idx].Height == height)
       return;

    FLUSH_VERTICES(ctx, ctx->DriverFlags.NewViewport ? 0 : _NEW_VIEWPORT);
    ctx->NewDriverState |= ctx->DriverFlags.NewViewport;

    ctx->ViewportArray[idx].X = x;
    ctx->ViewportArray[idx].Width = width;
    ctx->ViewportArray[idx].Y = y;
    ctx->ViewportArray[idx].Height = height;
 }

 struct gl_viewport_inputs {
    GLfloat X, Y;                /**< position */
    GLfloat Width, Height;       /**< size */
 };

 struct gl_depthrange_inputs {
    GLdouble Near, Far;          /**< Depth buffer range */
 };

 static void
 viewport(struct gl_context *ctx, GLint x, GLint y, GLsizei width,
          GLsizei height)
 {
    struct gl_viewport_inputs input = { x, y, width, height };

    /* Clamp the viewport to the implementation dependent values. */
    clamp_viewport(ctx, &input.X, &input.Y, &input.Width, &input.Height);

    /* The GL_ARB_viewport_array spec says:
     *
     *     "Viewport sets the parameters for all viewports to the same values
     *     and is equivalent (assuming no errors are generated) to:
     *
     *     for (uint i = 0; i < MAX_VIEWPORTS; i++)
     *         ViewportIndexedf(i, 1, (float)x, (float)y, (float)w, (float)h);"
     *
     * Set all of the viewports supported by the implementation, but only
     * signal the driver once at the end.
     */
    for (unsigned i = 0; i < ctx->Const.MaxViewports; i++)
       set_viewport_no_notify(ctx, i, input.X, input.Y, input.Width, input.Height);

    if (ctx->Driver.Viewport)
       ctx->Driver.Viewport(ctx);
 }

 /**
  * Set the viewport.
  * \sa Called via glViewport() or display list execution.
  *
  * Flushes the vertices and calls _mesa_set_viewport() with the given
  * parameters.
  */
 void GLAPIENTRY
 _mesa_Viewport_no_error(GLint x, GLint y, GLsizei width, GLsizei height)
 {
    GET_CURRENT_CONTEXT(ctx);
    viewport(ctx, x, y, width, height);
 }

 void GLAPIENTRY
 _mesa_Viewport(GLint x, GLint y, GLsizei width, GLsizei height)
 {
    GET_CURRENT_CONTEXT(ctx);

    if (MESA_VERBOSE & VERBOSE_API)
       _mesa_debug(ctx, "glViewport %d %d %d %d\n", x, y, width, height);

    if (width < 0 || height < 0) {
       _mesa_error(ctx,  GL_INVALID_VALUE,
                    "glViewport(%d, %d, %d, %d)", x, y, width, height);
       return;
    }

    viewport(ctx, x, y, width, height);
 }


 /**
  * Set new viewport parameters and update derived state.
  * Usually called from _mesa_Viewport().
  *
  * \param ctx GL context.
  * \param idx    Index of the viewport to be updated.
  * \param x, y coordinates of the lower left corner of the viewport rectangle.
  * \param width width of the viewport rectangle.
  * \param height height of the viewport rectangle.
  */
 void
 _mesa_set_viewport(struct gl_context *ctx, unsigned idx, GLfloat x, GLfloat y,
                     GLfloat width, GLfloat height)
 {
    clamp_viewport(ctx, &x, &y, &width, &height);
    set_viewport_no_notify(ctx, idx, x, y, width, height);

    if (ctx->Driver.Viewport)
       ctx->Driver.Viewport(ctx);
 }

 static void
 viewport_array(struct gl_context *ctx, GLuint first, GLsizei count,
                struct gl_viewport_inputs *inputs)
 {
    for (GLsizei i = 0; i < count; i++) {
       clamp_viewport(ctx, &inputs[i].X, &inputs[i].Y,
                      &inputs[i].Width, &inputs[i].Height);

       set_viewport_no_notify(ctx, i + first, inputs[i].X, inputs[i].Y,
                              inputs[i].Width, inputs[i].Height);
    }

    if (ctx->Driver.Viewport)
       ctx->Driver.Viewport(ctx);
 }

 void GLAPIENTRY
 _mesa_ViewportArrayv_no_error(GLuint first, GLsizei count, const GLfloat *v)
 {
    GET_CURRENT_CONTEXT(ctx);

    struct gl_viewport_inputs *p = (struct gl_viewport_inputs *)v;
    viewport_array(ctx, first, count, p);
 }

 void GLAPIENTRY
 _mesa_ViewportArrayv(GLuint first, GLsizei count, const GLfloat *v)
 {
    int i;
    struct gl_viewport_inputs *p = (struct gl_viewport_inputs *)v;
    GET_CURRENT_CONTEXT(ctx);

    if (MESA_VERBOSE & VERBOSE_API)
       _mesa_debug(ctx, "glViewportArrayv %d %d\n", first, count);

    if ((first + count) > ctx->Const.MaxViewports) {
       _mesa_error(ctx, GL_INVALID_VALUE,
                   "glViewportArrayv: first (%d) + count (%d) > MaxViewports "
                   "(%d)",
                   first, count, ctx->Const.MaxViewports);
       return;
    }

    /* Verify width & height */
    for (i = 0; i < count; i++) {
       if (p[i].Width < 0 || p[i].Height < 0) {
          _mesa_error(ctx, GL_INVALID_VALUE,
                      "glViewportArrayv: index (%d) width or height < 0 "
                      "(%f, %f)",
                      i + first, p[i].Width, p[i].Height);
          return;
       }
    }

    viewport_array(ctx, first, count, p);
 }

 static void
 viewport_indexed_err(struct gl_context *ctx, GLuint index, GLfloat x, GLfloat y,
                      GLfloat w, GLfloat h, const char *function)
 {
    if (MESA_VERBOSE & VERBOSE_API)
       _mesa_debug(ctx, "%s(%d, %f, %f, %f, %f)\n",
                   function, index, x, y, w, h);

    if (index >= ctx->Const.MaxViewports) {
       _mesa_error(ctx, GL_INVALID_VALUE,
                   "%s: index (%d) >= MaxViewports (%d)",
                   function, index, ctx->Const.MaxViewports);
       return;
    }

    /* Verify width & height */
    if (w < 0 || h < 0) {
       _mesa_error(ctx, GL_INVALID_VALUE,
                   "%s: index (%d) width or height < 0 (%f, %f)",
                   function, index, w, h);
       return;
    }

    _mesa_set_viewport(ctx, index, x, y, w, h);
 }

 void GLAPIENTRY
 _mesa_ViewportIndexedf_no_error(GLuint index, GLfloat x, GLfloat y,
                                 GLfloat w, GLfloat h)
 {
    GET_CURRENT_CONTEXT(ctx);
    _mesa_set_viewport(ctx, index, x, y, w, h);
 }

 void GLAPIENTRY
 _mesa_ViewportIndexedf(GLuint index, GLfloat x, GLfloat y,
                        GLfloat w, GLfloat h)
 {
    GET_CURRENT_CONTEXT(ctx);
    viewport_indexed_err(ctx, index, x, y, w, h, "glViewportIndexedf");
 }

 void GLAPIENTRY
 _mesa_ViewportIndexedfv_no_error(GLuint index, const GLfloat *v)
 {
    GET_CURRENT_CONTEXT(ctx);
    _mesa_set_viewport(ctx, index, v[0], v[1], v[2], v[3]);
 }

 void GLAPIENTRY
 _mesa_ViewportIndexedfv(GLuint index, const GLfloat *v)
 {
    GET_CURRENT_CONTEXT(ctx);
    viewport_indexed_err(ctx, index, v[0], v[1], v[2], v[3],
                         "glViewportIndexedfv");
 }

 static void
 set_depth_range_no_notify(struct gl_context *ctx, unsigned idx,
                           GLclampd nearval, GLclampd farval)
 {
    if (ctx->ViewportArray[idx].Near == nearval &&
        ctx->ViewportArray[idx].Far == farval)
       return;

    /* The depth range is needed by program state constants. */
    FLUSH_VERTICES(ctx, _NEW_VIEWPORT);
    ctx->NewDriverState |= ctx->DriverFlags.NewViewport;

    ctx->ViewportArray[idx].Near = SATURATE(nearval);
    ctx->ViewportArray[idx].Far = SATURATE(farval);
 }

 void
 _mesa_set_depth_range(struct gl_context *ctx, unsigned idx,
                       GLclampd nearval, GLclampd farval)
 {
    set_depth_range_no_notify(ctx, idx, nearval, farval);

    if (ctx->Driver.DepthRange)
       ctx->Driver.DepthRange(ctx);
 }

 /**
  * Called by glDepthRange
  *
  * \param nearval  specifies the Z buffer value which should correspond to
  *                 the near clip plane
  * \param farval  specifies the Z buffer value which should correspond to
  *                the far clip plane
  */
 void GLAPIENTRY
 _mesa_DepthRange(GLclampd nearval, GLclampd farval)
 {
    unsigned i;
    GET_CURRENT_CONTEXT(ctx);

    if (MESA_VERBOSE&VERBOSE_API)
       _mesa_debug(ctx, "glDepthRange %f %f\n", nearval, farval);

    /* The GL_ARB_viewport_array spec says:
     *
     *     "DepthRange sets the depth range for all viewports to the same
     *     values and is equivalent (assuming no errors are generated) to:
     *
     *     for (uint i = 0; i < MAX_VIEWPORTS; i++)
     *         DepthRangeIndexed(i, n, f);"
     *
     * Set the depth range for all of the viewports supported by the
     * implementation, but only signal the driver once at the end.
     */
    for (i = 0; i < ctx->Const.MaxViewports; i++)
       set_depth_range_no_notify(ctx, i, nearval, farval);

    if (ctx->Driver.DepthRange) {
       ctx->Driver.DepthRange(ctx);
    }
 }

 void GLAPIENTRY
 _mesa_DepthRangef(GLclampf nearval, GLclampf farval)
 {
    _mesa_DepthRange(nearval, farval);
 }

 /**
  * Update a range DepthRange values
  *
  * \param first   starting array index
  * \param count   count of DepthRange items to update
  * \param v       pointer to memory containing
  *                GLclampd near and far clip-plane values
  */
 static ALWAYS_INLINE void
 depth_range_arrayv(struct gl_context *ctx, GLuint first, GLsizei count,
                    const struct gl_depthrange_inputs *const inputs)
 {
    for (GLsizei i = 0; i < count; i++)
       set_depth_range_no_notify(ctx, i + first, inputs[i].Near, inputs[i].Far);

    if (ctx->Driver.DepthRange)
       ctx->Driver.DepthRange(ctx);
 }

 void GLAPIENTRY
 _mesa_DepthRangeArrayv_no_error(GLuint first, GLsizei count, const GLclampd *v)
 {
    GET_CURRENT_CONTEXT(ctx);

    const struct gl_depthrange_inputs *const p =
       (struct gl_depthrange_inputs *)v;
    depth_range_arrayv(ctx, first, count, p);
 }

 void GLAPIENTRY
 _mesa_DepthRangeArrayv(GLuint first, GLsizei count, const GLclampd *v)
 {
    const struct gl_depthrange_inputs *const p =
       (struct gl_depthrange_inputs *) v;
    GET_CURRENT_CONTEXT(ctx);

    if (MESA_VERBOSE & VERBOSE_API)
       _mesa_debug(ctx, "glDepthRangeArrayv %d %d\n", first, count);

    if ((first + count) > ctx->Const.MaxViewports) {
       _mesa_error(ctx, GL_INVALID_VALUE,
                   "glDepthRangev: first (%d) + count (%d) >= MaxViewports (%d)",
                   first, count, ctx->Const.MaxViewports);
       return;
    }

    depth_range_arrayv(ctx, first, count, p);
 }

 void GLAPIENTRY
 _mesa_DepthRangeArrayfvOES(GLuint first, GLsizei count, const GLfloat *v)
 {
    int i;
    GET_CURRENT_CONTEXT(ctx);

    if (MESA_VERBOSE & VERBOSE_API)
       _mesa_debug(ctx, "glDepthRangeArrayfv %d %d\n", first, count);

    if ((first + count) > ctx->Const.MaxViewports) {
       _mesa_error(ctx, GL_INVALID_VALUE,
                   "glDepthRangeArrayfv: first (%d) + count (%d) >= MaxViewports (%d)",
                   first, count, ctx->Const.MaxViewports);
       return;
    }

    for (i = 0; i < count; i++)
       set_depth_range_no_notify(ctx, i + first, v[i * 2], v[i * 2 + 1]);

    if (ctx->Driver.DepthRange)
       ctx->Driver.DepthRange(ctx);
 }

 /**
  * Update a single DepthRange
  *
  * \param index    array index to update
  * \param nearval  specifies the Z buffer value which should correspond to
  *                 the near clip plane
  * \param farval   specifies the Z buffer value which should correspond to
  *                 the far clip plane
  */
 void GLAPIENTRY
 _mesa_DepthRangeIndexed_no_error(GLuint index, GLclampd nearval,
                                  GLclampd farval)
 {
    GET_CURRENT_CONTEXT(ctx);
    _mesa_set_depth_range(ctx, index, nearval, farval);
 }


 void GLAPIENTRY
 _mesa_DepthRangeIndexed(GLuint index, GLclampd nearval, GLclampd farval)
 {
    GET_CURRENT_CONTEXT(ctx);

    if (MESA_VERBOSE & VERBOSE_API)
       _mesa_debug(ctx, "glDepthRangeIndexed(%d, %f, %f)\n",
                   index, nearval, farval);

    if (index >= ctx->Const.MaxViewports) {
       _mesa_error(ctx, GL_INVALID_VALUE,
                   "glDepthRangeIndexed: index (%d) >= MaxViewports (%d)",
                   index, ctx->Const.MaxViewports);
       return;
    }

    _mesa_set_depth_range(ctx, index, nearval, farval);
 }

 void GLAPIENTRY
 _mesa_DepthRangeIndexedfOES(GLuint index, GLfloat nearval, GLfloat farval)
 {
    _mesa_DepthRangeIndexed(index, nearval, farval);
 }

 /**
  * Initialize the context viewport attribute group.
  * \param ctx  the GL context.
  */
 void _mesa_init_viewport(struct gl_context *ctx)
 {
    unsigned i;

    ctx->Transform.ClipOrigin = GL_LOWER_LEFT;
    ctx->Transform.ClipDepthMode = GL_NEGATIVE_ONE_TO_ONE;

    /* Note: ctx->Const.MaxViewports may not have been set by the driver yet,
     * so just initialize all of them.
     */
    for (i = 0; i < MAX_VIEWPORTS; i++) {
       /* Viewport group */
       ctx->ViewportArray[i].X = 0;
       ctx->ViewportArray[i].Y = 0;
       ctx->ViewportArray[i].Width = 0;
       ctx->ViewportArray[i].Height = 0;
       ctx->ViewportArray[i].Near = 0.0;
       ctx->ViewportArray[i].Far = 1.0;
       ctx->ViewportArray[i].SwizzleX = GL_VIEWPORT_SWIZZLE_POSITIVE_X_NV;
       ctx->ViewportArray[i].SwizzleY = GL_VIEWPORT_SWIZZLE_POSITIVE_Y_NV;
       ctx->ViewportArray[i].SwizzleZ = GL_VIEWPORT_SWIZZLE_POSITIVE_Z_NV;
       ctx->ViewportArray[i].SwizzleW = GL_VIEWPORT_SWIZZLE_POSITIVE_W_NV;
    }

    ctx->SubpixelPrecisionBias[0] = 0;
    ctx->SubpixelPrecisionBias[1] = 0;
 }


 static ALWAYS_INLINE void
 clip_control(struct gl_context *ctx, GLenum origin, GLenum depth, bool no_error)
 {
    if (ctx->Transform.ClipOrigin == origin &&
        ctx->Transform.ClipDepthMode == depth)
       return;

    if (!no_error &&
        origin != GL_LOWER_LEFT && origin != GL_UPPER_LEFT) {
       _mesa_error(ctx, GL_INVALID_ENUM, "glClipControl");
       return;
    }

    if (!no_error &&
        depth != GL_NEGATIVE_ONE_TO_ONE && depth != GL_ZERO_TO_ONE) {
       _mesa_error(ctx, GL_INVALID_ENUM, "glClipControl");
       return;
    }

    /* Affects transform state and the viewport transform */
    FLUSH_VERTICES(ctx, ctx->DriverFlags.NewClipControl ? 0 :
                   _NEW_TRANSFORM | _NEW_VIEWPORT);
    ctx->NewDriverState |= ctx->DriverFlags.NewClipControl;

    if (ctx->Transform.ClipOrigin != origin) {
       ctx->Transform.ClipOrigin = origin;

       /* Affects the winding order of the front face. */
       if (ctx->DriverFlags.NewPolygonState)
          ctx->NewDriverState |= ctx->DriverFlags.NewPolygonState;
       else
          ctx->NewState |= _NEW_POLYGON;

       if (ctx->Driver.FrontFace)
          ctx->Driver.FrontFace(ctx, ctx->Polygon.FrontFace);
    }

    if (ctx->Transform.ClipDepthMode != depth) {
       ctx->Transform.ClipDepthMode = depth;

       if (ctx->Driver.DepthRange)
          ctx->Driver.DepthRange(ctx);
    }
 }


 void GLAPIENTRY
 _mesa_ClipControl_no_error(GLenum origin, GLenum depth)
 {
    GET_CURRENT_CONTEXT(ctx);
    clip_control(ctx, origin, depth, true);
 }


 void GLAPIENTRY
 _mesa_ClipControl(GLenum origin, GLenum depth)
 {
    GET_CURRENT_CONTEXT(ctx);

    if (MESA_VERBOSE & VERBOSE_API)
       _mesa_debug(ctx, "glClipControl(%s, %s)\n",
 	          _mesa_enum_to_string(origin),
                   _mesa_enum_to_string(depth));

    ASSERT_OUTSIDE_BEGIN_END(ctx);

    if (!ctx->Extensions.ARB_clip_control) {
       _mesa_error(ctx, GL_INVALID_OPERATION, "glClipControl");
       return;
    }

    clip_control(ctx, origin, depth, false);
 }

 /**
  * Computes the scaling and the translation part of the
  * viewport transform matrix of the \param i-th viewport
  * and writes that into \param scale and \param translate.
  */
 void
 _mesa_get_viewport_xform(struct gl_context *ctx, unsigned i,
                          float scale[3], float translate[3])
 {
    float x = ctx->ViewportArray[i].X;
    float y = ctx->ViewportArray[i].Y;
    float half_width = 0.5f * ctx->ViewportArray[i].Width;
    float half_height = 0.5f * ctx->ViewportArray[i].Height;
    double n = ctx->ViewportArray[i].Near;
    double f = ctx->ViewportArray[i].Far;

    scale[0] = half_width;
    translate[0] = half_width + x;
    if (ctx->Transform.ClipOrigin == GL_UPPER_LEFT) {
       scale[1] = -half_height;
    } else {
       scale[1] = half_height;
    }
    translate[1] = half_height + y;

    if (ctx->Transform.ClipDepthMode == GL_NEGATIVE_ONE_TO_ONE) {
       scale[2] = 0.5 * (f - n);
       translate[2] = 0.5 * (n + f);
    } else {
       scale[2] = f - n;
       translate[2] = n;
    }
 }


 static void
 subpixel_precision_bias(struct gl_context *ctx, GLuint xbits, GLuint ybits)
 {
    if (MESA_VERBOSE & VERBOSE_API)
       _mesa_debug(ctx, "glSubpixelPrecisionBiasNV(%u, %u)\n", xbits, ybits);

    FLUSH_VERTICES(ctx, 0);

    ctx->SubpixelPrecisionBias[0] = xbits;
    ctx->SubpixelPrecisionBias[1] = ybits;

    ctx->NewDriverState |=
       ctx->DriverFlags.NewNvConservativeRasterizationParams;
 }

 void GLAPIENTRY
 _mesa_SubpixelPrecisionBiasNV_no_error(GLuint xbits, GLuint ybits)
 {
    GET_CURRENT_CONTEXT(ctx);

    if (MESA_VERBOSE & VERBOSE_API)
       _mesa_debug(ctx, "glSubpixelPrecisionBiasNV(%u, %u)\n", xbits, ybits);

    subpixel_precision_bias(ctx, xbits, ybits);
 }

 void GLAPIENTRY
 _mesa_SubpixelPrecisionBiasNV(GLuint xbits, GLuint ybits)
 {
    GET_CURRENT_CONTEXT(ctx);

    if (MESA_VERBOSE & VERBOSE_API)
       _mesa_debug(ctx, "glSubpixelPrecisionBiasNV(%u, %u)\n", xbits, ybits);

    ASSERT_OUTSIDE_BEGIN_END(ctx);

    if (!ctx->Extensions.NV_conservative_raster) {
       _mesa_error(ctx, GL_INVALID_OPERATION,
                   "glSubpixelPrecisionBiasNV not supported");
       return;
    }

    if (xbits > ctx->Const.MaxSubpixelPrecisionBiasBits) {
       _mesa_error(ctx, GL_INVALID_VALUE, "glSubpixelPrecisionBiasNV");
       return;
    }

    if (ybits > ctx->Const.MaxSubpixelPrecisionBiasBits) {
       _mesa_error(ctx, GL_INVALID_VALUE, "glSubpixelPrecisionBiasNV");
       return;
    }

    subpixel_precision_bias(ctx, xbits, ybits);
 }

 static void
 set_viewport_swizzle(struct gl_context *ctx, GLuint index,
                      GLenum swizzlex, GLenum swizzley,
                      GLenum swizzlez, GLenum swizzlew)
 {
    struct gl_viewport_attrib *viewport = &ctx->ViewportArray[index];
    if (viewport->SwizzleX == swizzlex &&
        viewport->SwizzleY == swizzley &&
        viewport->SwizzleZ == swizzlez &&
        viewport->SwizzleW == swizzlew)
       return;

    FLUSH_VERTICES(ctx, _NEW_VIEWPORT);
    ctx->NewDriverState |= ctx->DriverFlags.NewViewport;

    viewport->SwizzleX = swizzlex;
    viewport->SwizzleY = swizzley;
    viewport->SwizzleZ = swizzlez;
    viewport->SwizzleW = swizzlew;
 }

 void GLAPIENTRY
 _mesa_ViewportSwizzleNV_no_error(GLuint index,
                                  GLenum swizzlex, GLenum swizzley,
                                  GLenum swizzlez, GLenum swizzlew)
 {
    GET_CURRENT_CONTEXT(ctx);

    if (MESA_VERBOSE & VERBOSE_API)
       _mesa_debug(ctx, "glViewportSwizzleNV(%x, %x, %x, %x)\n",
                   swizzlex, swizzley, swizzlez, swizzlew);

    set_viewport_swizzle(ctx, index, swizzlex, swizzley, swizzlez, swizzlew);
 }

 static bool
 verify_viewport_swizzle(GLenum swizzle)
 {
    return swizzle >= GL_VIEWPORT_SWIZZLE_POSITIVE_X_NV &&
       swizzle <= GL_VIEWPORT_SWIZZLE_NEGATIVE_W_NV;
 }

 void GLAPIENTRY
 _mesa_ViewportSwizzleNV(GLuint index,
                         GLenum swizzlex, GLenum swizzley,
                         GLenum swizzlez, GLenum swizzlew)
 {
    GET_CURRENT_CONTEXT(ctx);

    if (MESA_VERBOSE & VERBOSE_API)
       _mesa_debug(ctx, "glViewportSwizzleNV(%x, %x, %x, %x)\n",
                   swizzlex, swizzley, swizzlez, swizzlew);

    if (!ctx->Extensions.NV_viewport_swizzle) {
       _mesa_error(ctx, GL_INVALID_OPERATION,
                   "glViewportSwizzleNV not supported");
       return;
    }

    if (index >= ctx->Const.MaxViewports) {
       _mesa_error(ctx, GL_INVALID_VALUE,
                   "glViewportSwizzleNV: index (%d) >= MaxViewports (%d)",
                   index, ctx->Const.MaxViewports);
       return;
    }

    if (!verify_viewport_swizzle(swizzlex)) {
       _mesa_error(ctx, GL_INVALID_ENUM,
                   "glViewportSwizzleNV(swizzlex=%x)", swizzlex);
       return;
    }

    if (!verify_viewport_swizzle(swizzley)) {
       _mesa_error(ctx, GL_INVALID_ENUM,
                   "glViewportSwizzleNV(swizzley=%x)", swizzley);
       return;
    }

    if (!verify_viewport_swizzle(swizzlez)) {
       _mesa_error(ctx, GL_INVALID_ENUM,
                   "glViewportSwizzleNV(swizzlez=%x)", swizzlez);
       return;
    }

    if (!verify_viewport_swizzle(swizzlew)) {
       _mesa_error(ctx, GL_INVALID_ENUM,
                   "glViewportSwizzleNV(swizzlew=%x)", swizzlew);
       return;
    }

    set_viewport_swizzle(ctx, index, swizzlex, swizzley, swizzlez, swizzlew);
 }
	/*
	* Mesa 3-D graphics library
	*
	* Copyright (C) 2009 VMware, Inc. All Rights Reserved.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the "Software"),
	* to deal in the Software without restriction, including without limitation
	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	* and/or sell copies of the Software, and to permit persons to whom the
	* Software is furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included
	* in all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
	* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
	* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
	* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
	* OTHER DEALINGS IN THE SOFTWARE.
	*/


	/**
	* \file viewport.c
	* glViewport and glDepthRange functions.
	*/


	#include "context.h"
	#include "enums.h"
	#include "macros.h"
	#include "mtypes.h"
	#include "viewport.h"

	static void
	clamp_viewport(struct gl_context ctx, GLfloat x, GLfloat *y,
	GLfloat width, GLfloat height)
	{
	/* clamp width and height to the implementation dependent range */
	width = MIN2(width, (GLfloat) ctx->Const.MaxViewportWidth);
	height = MIN2(height, (GLfloat) ctx->Const.MaxViewportHeight);

	/* The GL_ARB_viewport_array spec says:
	*
	* "The location of the viewport's bottom-left corner, given by (x,y),
	* are clamped to be within the implementation-dependent viewport
	* bounds range. The viewport bounds range [min, max] tuple may be
	* determined by calling GetFloatv with the symbolic constant
	* VIEWPORT_BOUNDS_RANGE (see section 6.1)."
	*/
	if (_mesa_has_ARB_viewport_array(ctx) \|\|
	_mesa_has_OES_viewport_array(ctx)) {
	x = CLAMP(x,
	ctx->Const.ViewportBounds.Min, ctx->Const.ViewportBounds.Max);
	y = CLAMP(y,
	ctx->Const.ViewportBounds.Min, ctx->Const.ViewportBounds.Max);
	}
	}

	static void
	set_viewport_no_notify(struct gl_context *ctx, unsigned idx,
	GLfloat x, GLfloat y,
	GLfloat width, GLfloat height)
	{
	if (ctx->ViewportArray[idx].X == x &&
	ctx->ViewportArray[idx].Width == width &&
	ctx->ViewportArray[idx].Y == y &&
	ctx->ViewportArray[idx].Height == height)
	return;

	FLUSH_VERTICES(ctx, ctx->DriverFlags.NewViewport ? 0 : _NEW_VIEWPORT);
	ctx->NewDriverState \|= ctx->DriverFlags.NewViewport;

	ctx->ViewportArray[idx].X = x;
	ctx->ViewportArray[idx].Width = width;
	ctx->ViewportArray[idx].Y = y;
	ctx->ViewportArray[idx].Height = height;
	}

	struct gl_viewport_inputs {
	GLfloat X, Y; /*< position /
	GLfloat Width, Height; /*< size /
	};

	struct gl_depthrange_inputs {
	GLdouble Near, Far; /*< Depth buffer range /
	};

	static void
	viewport(struct gl_context *ctx, GLint x, GLint y, GLsizei width,
	GLsizei height)
	{
	struct gl_viewport_inputs input = { x, y, width, height };

	/* Clamp the viewport to the implementation dependent values. */
	clamp_viewport(ctx, &input.X, &input.Y, &input.Width, &input.Height);

	/* The GL_ARB_viewport_array spec says:
	*
	* "Viewport sets the parameters for all viewports to the same values
	* and is equivalent (assuming no errors are generated) to:
	*
	* for (uint i = 0; i < MAX_VIEWPORTS; i++)
	* ViewportIndexedf(i, 1, (float)x, (float)y, (float)w, (float)h);"
	*
	* Set all of the viewports supported by the implementation, but only
	* signal the driver once at the end.
	*/
	for (unsigned i = 0; i < ctx->Const.MaxViewports; i++)
	set_viewport_no_notify(ctx, i, input.X, input.Y, input.Width, input.Height);

	if (ctx->Driver.Viewport)
	ctx->Driver.Viewport(ctx);
	}

	/**
	* Set the viewport.
	* \sa Called via glViewport() or display list execution.
	*
	* Flushes the vertices and calls _mesa_set_viewport() with the given
	* parameters.
	*/
	void GLAPIENTRY
	_mesa_Viewport_no_error(GLint x, GLint y, GLsizei width, GLsizei height)
	{
	GET_CURRENT_CONTEXT(ctx);
	viewport(ctx, x, y, width, height);
	}

	void GLAPIENTRY
	_mesa_Viewport(GLint x, GLint y, GLsizei width, GLsizei height)
	{
	GET_CURRENT_CONTEXT(ctx);

	if (MESA_VERBOSE & VERBOSE_API)
	_mesa_debug(ctx, "glViewport %d %d %d %d\n", x, y, width, height);

	if (width < 0 \|\| height < 0) {
	_mesa_error(ctx, GL_INVALID_VALUE,
	"glViewport(%d, %d, %d, %d)", x, y, width, height);
	return;
	}

	viewport(ctx, x, y, width, height);
	}


	/**
	* Set new viewport parameters and update derived state.
	* Usually called from _mesa_Viewport().
	*
	* \param ctx GL context.
	* \param idx Index of the viewport to be updated.
	* \param x, y coordinates of the lower left corner of the viewport rectangle.
	* \param width width of the viewport rectangle.
	* \param height height of the viewport rectangle.
	*/
	void
	_mesa_set_viewport(struct gl_context *ctx, unsigned idx, GLfloat x, GLfloat y,
	GLfloat width, GLfloat height)
	{
	clamp_viewport(ctx, &x, &y, &width, &height);
	set_viewport_no_notify(ctx, idx, x, y, width, height);

	if (ctx->Driver.Viewport)
	ctx->Driver.Viewport(ctx);
	}

	static void
	viewport_array(struct gl_context *ctx, GLuint first, GLsizei count,
	struct gl_viewport_inputs *inputs)
	{
	for (GLsizei i = 0; i < count; i++) {
	clamp_viewport(ctx, &inputs[i].X, &inputs[i].Y,
	&inputs[i].Width, &inputs[i].Height);

	set_viewport_no_notify(ctx, i + first, inputs[i].X, inputs[i].Y,
	inputs[i].Width, inputs[i].Height);
	}

	if (ctx->Driver.Viewport)
	ctx->Driver.Viewport(ctx);
	}

	void GLAPIENTRY
	_mesa_ViewportArrayv_no_error(GLuint first, GLsizei count, const GLfloat *v)
	{
	GET_CURRENT_CONTEXT(ctx);

	struct gl_viewport_inputs p = (struct gl_viewport_inputs )v;
	viewport_array(ctx, first, count, p);
	}

	void GLAPIENTRY
	_mesa_ViewportArrayv(GLuint first, GLsizei count, const GLfloat *v)
	{
	int i;
	struct gl_viewport_inputs p = (struct gl_viewport_inputs )v;
	GET_CURRENT_CONTEXT(ctx);

	if (MESA_VERBOSE & VERBOSE_API)
	_mesa_debug(ctx, "glViewportArrayv %d %d\n", first, count);

	if ((first + count) > ctx->Const.MaxViewports) {
	_mesa_error(ctx, GL_INVALID_VALUE,
	"glViewportArrayv: first (%d) + count (%d) > MaxViewports "
	"(%d)",
	first, count, ctx->Const.MaxViewports);
	return;
	}

	/* Verify width & height */
	for (i = 0; i < count; i++) {
	if (p[i].Width < 0 \|\| p[i].Height < 0) {
	_mesa_error(ctx, GL_INVALID_VALUE,
	"glViewportArrayv: index (%d) width or height < 0 "
	"(%f, %f)",
	i + first, p[i].Width, p[i].Height);
	return;
	}
	}

	viewport_array(ctx, first, count, p);
	}

	static void
	viewport_indexed_err(struct gl_context *ctx, GLuint index, GLfloat x, GLfloat y,
	GLfloat w, GLfloat h, const char *function)
	{
	if (MESA_VERBOSE & VERBOSE_API)
	_mesa_debug(ctx, "%s(%d, %f, %f, %f, %f)\n",
	function, index, x, y, w, h);

	if (index >= ctx->Const.MaxViewports) {
	_mesa_error(ctx, GL_INVALID_VALUE,
	"%s: index (%d) >= MaxViewports (%d)",
	function, index, ctx->Const.MaxViewports);
	return;
	}

	/* Verify width & height */
	if (w < 0 \|\| h < 0) {
	_mesa_error(ctx, GL_INVALID_VALUE,
	"%s: index (%d) width or height < 0 (%f, %f)",
	function, index, w, h);
	return;
	}

	_mesa_set_viewport(ctx, index, x, y, w, h);
	}

	void GLAPIENTRY
	_mesa_ViewportIndexedf_no_error(GLuint index, GLfloat x, GLfloat y,
	GLfloat w, GLfloat h)
	{
	GET_CURRENT_CONTEXT(ctx);
	_mesa_set_viewport(ctx, index, x, y, w, h);
	}

	void GLAPIENTRY
	_mesa_ViewportIndexedf(GLuint index, GLfloat x, GLfloat y,
	GLfloat w, GLfloat h)
	{
	GET_CURRENT_CONTEXT(ctx);
	viewport_indexed_err(ctx, index, x, y, w, h, "glViewportIndexedf");
	}

	void GLAPIENTRY
	_mesa_ViewportIndexedfv_no_error(GLuint index, const GLfloat *v)
	{
	GET_CURRENT_CONTEXT(ctx);
	_mesa_set_viewport(ctx, index, v[0], v[1], v[2], v[3]);
	}

	void GLAPIENTRY
	_mesa_ViewportIndexedfv(GLuint index, const GLfloat *v)
	{
	GET_CURRENT_CONTEXT(ctx);
	viewport_indexed_err(ctx, index, v[0], v[1], v[2], v[3],
	"glViewportIndexedfv");
	}

	static void
	set_depth_range_no_notify(struct gl_context *ctx, unsigned idx,
	GLclampd nearval, GLclampd farval)
	{
	if (ctx->ViewportArray[idx].Near == nearval &&
	ctx->ViewportArray[idx].Far == farval)
	return;

	/* The depth range is needed by program state constants. */
	FLUSH_VERTICES(ctx, _NEW_VIEWPORT);
	ctx->NewDriverState \|= ctx->DriverFlags.NewViewport;

	ctx->ViewportArray[idx].Near = SATURATE(nearval);
	ctx->ViewportArray[idx].Far = SATURATE(farval);
	}

	void
	_mesa_set_depth_range(struct gl_context *ctx, unsigned idx,
	GLclampd nearval, GLclampd farval)
	{
	set_depth_range_no_notify(ctx, idx, nearval, farval);

	if (ctx->Driver.DepthRange)
	ctx->Driver.DepthRange(ctx);
	}

	/**
	* Called by glDepthRange
	*
	* \param nearval specifies the Z buffer value which should correspond to
	* the near clip plane
	* \param farval specifies the Z buffer value which should correspond to
	* the far clip plane
	*/
	void GLAPIENTRY
	_mesa_DepthRange(GLclampd nearval, GLclampd farval)
	{
	unsigned i;
	GET_CURRENT_CONTEXT(ctx);

	if (MESA_VERBOSE&VERBOSE_API)
	_mesa_debug(ctx, "glDepthRange %f %f\n", nearval, farval);

	/* The GL_ARB_viewport_array spec says:
	*
	* "DepthRange sets the depth range for all viewports to the same
	* values and is equivalent (assuming no errors are generated) to:
	*
	* for (uint i = 0; i < MAX_VIEWPORTS; i++)
	* DepthRangeIndexed(i, n, f);"
	*
	* Set the depth range for all of the viewports supported by the
	* implementation, but only signal the driver once at the end.
	*/
	for (i = 0; i < ctx->Const.MaxViewports; i++)
	set_depth_range_no_notify(ctx, i, nearval, farval);

	if (ctx->Driver.DepthRange) {
	ctx->Driver.DepthRange(ctx);
	}
	}

	void GLAPIENTRY
	_mesa_DepthRangef(GLclampf nearval, GLclampf farval)
	{
	_mesa_DepthRange(nearval, farval);
	}

	/**
	* Update a range DepthRange values
	*
	* \param first starting array index
	* \param count count of DepthRange items to update
	* \param v pointer to memory containing
	* GLclampd near and far clip-plane values
	*/
	static ALWAYS_INLINE void
	depth_range_arrayv(struct gl_context *ctx, GLuint first, GLsizei count,
	const struct gl_depthrange_inputs *const inputs)
	{
	for (GLsizei i = 0; i < count; i++)
	set_depth_range_no_notify(ctx, i + first, inputs[i].Near, inputs[i].Far);

	if (ctx->Driver.DepthRange)
	ctx->Driver.DepthRange(ctx);
	}

	void GLAPIENTRY
	_mesa_DepthRangeArrayv_no_error(GLuint first, GLsizei count, const GLclampd *v)
	{
	GET_CURRENT_CONTEXT(ctx);

	const struct gl_depthrange_inputs *const p =
	(struct gl_depthrange_inputs *)v;
	depth_range_arrayv(ctx, first, count, p);
	}

	void GLAPIENTRY
	_mesa_DepthRangeArrayv(GLuint first, GLsizei count, const GLclampd *v)
	{
	const struct gl_depthrange_inputs *const p =
	(struct gl_depthrange_inputs *) v;
	GET_CURRENT_CONTEXT(ctx);

	if (MESA_VERBOSE & VERBOSE_API)
	_mesa_debug(ctx, "glDepthRangeArrayv %d %d\n", first, count);

	if ((first + count) > ctx->Const.MaxViewports) {
	_mesa_error(ctx, GL_INVALID_VALUE,
	"glDepthRangev: first (%d) + count (%d) >= MaxViewports (%d)",
	first, count, ctx->Const.MaxViewports);
	return;
	}

	depth_range_arrayv(ctx, first, count, p);
	}

	void GLAPIENTRY
	_mesa_DepthRangeArrayfvOES(GLuint first, GLsizei count, const GLfloat *v)
	{
	int i;
	GET_CURRENT_CONTEXT(ctx);

	if (MESA_VERBOSE & VERBOSE_API)
	_mesa_debug(ctx, "glDepthRangeArrayfv %d %d\n", first, count);

	if ((first + count) > ctx->Const.MaxViewports) {
	_mesa_error(ctx, GL_INVALID_VALUE,
	"glDepthRangeArrayfv: first (%d) + count (%d) >= MaxViewports (%d)",
	first, count, ctx->Const.MaxViewports);
	return;
	}

	for (i = 0; i < count; i++)
	set_depth_range_no_notify(ctx, i + first, v[i * 2], v[i * 2 + 1]);

	if (ctx->Driver.DepthRange)
	ctx->Driver.DepthRange(ctx);
	}

	/**
	* Update a single DepthRange
	*
	* \param index array index to update
	* \param nearval specifies the Z buffer value which should correspond to
	* the near clip plane
	* \param farval specifies the Z buffer value which should correspond to
	* the far clip plane
	*/
	void GLAPIENTRY
	_mesa_DepthRangeIndexed_no_error(GLuint index, GLclampd nearval,
	GLclampd farval)
	{
	GET_CURRENT_CONTEXT(ctx);
	_mesa_set_depth_range(ctx, index, nearval, farval);
	}


	void GLAPIENTRY
	_mesa_DepthRangeIndexed(GLuint index, GLclampd nearval, GLclampd farval)
	{
	GET_CURRENT_CONTEXT(ctx);

	if (MESA_VERBOSE & VERBOSE_API)
	_mesa_debug(ctx, "glDepthRangeIndexed(%d, %f, %f)\n",
	index, nearval, farval);

	if (index >= ctx->Const.MaxViewports) {
	_mesa_error(ctx, GL_INVALID_VALUE,
	"glDepthRangeIndexed: index (%d) >= MaxViewports (%d)",
	index, ctx->Const.MaxViewports);
	return;
	}

	_mesa_set_depth_range(ctx, index, nearval, farval);
	}

	void GLAPIENTRY
	_mesa_DepthRangeIndexedfOES(GLuint index, GLfloat nearval, GLfloat farval)
	{
	_mesa_DepthRangeIndexed(index, nearval, farval);
	}

	/**
	* Initialize the context viewport attribute group.
	* \param ctx the GL context.
	*/
	void _mesa_init_viewport(struct gl_context *ctx)
	{
	unsigned i;

	ctx->Transform.ClipOrigin = GL_LOWER_LEFT;
	ctx->Transform.ClipDepthMode = GL_NEGATIVE_ONE_TO_ONE;

	/* Note: ctx->Const.MaxViewports may not have been set by the driver yet,
	* so just initialize all of them.
	*/
	for (i = 0; i < MAX_VIEWPORTS; i++) {
	/* Viewport group */
	ctx->ViewportArray[i].X = 0;
	ctx->ViewportArray[i].Y = 0;
	ctx->ViewportArray[i].Width = 0;
	ctx->ViewportArray[i].Height = 0;
	ctx->ViewportArray[i].Near = 0.0;
	ctx->ViewportArray[i].Far = 1.0;
	ctx->ViewportArray[i].SwizzleX = GL_VIEWPORT_SWIZZLE_POSITIVE_X_NV;
	ctx->ViewportArray[i].SwizzleY = GL_VIEWPORT_SWIZZLE_POSITIVE_Y_NV;
	ctx->ViewportArray[i].SwizzleZ = GL_VIEWPORT_SWIZZLE_POSITIVE_Z_NV;
	ctx->ViewportArray[i].SwizzleW = GL_VIEWPORT_SWIZZLE_POSITIVE_W_NV;
	}

	ctx->SubpixelPrecisionBias[0] = 0;
	ctx->SubpixelPrecisionBias[1] = 0;
	}


	static ALWAYS_INLINE void
	clip_control(struct gl_context *ctx, GLenum origin, GLenum depth, bool no_error)
	{
	if (ctx->Transform.ClipOrigin == origin &&
	ctx->Transform.ClipDepthMode == depth)
	return;

	if (!no_error &&
	origin != GL_LOWER_LEFT && origin != GL_UPPER_LEFT) {
	_mesa_error(ctx, GL_INVALID_ENUM, "glClipControl");
	return;
	}

	if (!no_error &&
	depth != GL_NEGATIVE_ONE_TO_ONE && depth != GL_ZERO_TO_ONE) {
	_mesa_error(ctx, GL_INVALID_ENUM, "glClipControl");
	return;
	}

	/* Affects transform state and the viewport transform */
	FLUSH_VERTICES(ctx, ctx->DriverFlags.NewClipControl ? 0 :
	_NEW_TRANSFORM \| _NEW_VIEWPORT);
	ctx->NewDriverState \|= ctx->DriverFlags.NewClipControl;

	if (ctx->Transform.ClipOrigin != origin) {
	ctx->Transform.ClipOrigin = origin;

	/* Affects the winding order of the front face. */
	if (ctx->DriverFlags.NewPolygonState)
	ctx->NewDriverState \|= ctx->DriverFlags.NewPolygonState;
	else
	ctx->NewState \|= _NEW_POLYGON;

	if (ctx->Driver.FrontFace)
	ctx->Driver.FrontFace(ctx, ctx->Polygon.FrontFace);
	}

	if (ctx->Transform.ClipDepthMode != depth) {
	ctx->Transform.ClipDepthMode = depth;

	if (ctx->Driver.DepthRange)
	ctx->Driver.DepthRange(ctx);
	}
	}


	void GLAPIENTRY
	_mesa_ClipControl_no_error(GLenum origin, GLenum depth)
	{
	GET_CURRENT_CONTEXT(ctx);
	clip_control(ctx, origin, depth, true);
	}


	void GLAPIENTRY
	_mesa_ClipControl(GLenum origin, GLenum depth)
	{
	GET_CURRENT_CONTEXT(ctx);

	if (MESA_VERBOSE & VERBOSE_API)
	_mesa_debug(ctx, "glClipControl(%s, %s)\n",
	_mesa_enum_to_string(origin),
	_mesa_enum_to_string(depth));

	ASSERT_OUTSIDE_BEGIN_END(ctx);

	if (!ctx->Extensions.ARB_clip_control) {
	_mesa_error(ctx, GL_INVALID_OPERATION, "glClipControl");
	return;
	}

	clip_control(ctx, origin, depth, false);
	}

	/**
	* Computes the scaling and the translation part of the
	* viewport transform matrix of the \param i-th viewport
	* and writes that into \param scale and \param translate.
	*/
	void
	_mesa_get_viewport_xform(struct gl_context *ctx, unsigned i,
	float scale[3], float translate[3])
	{
	float x = ctx->ViewportArray[i].X;
	float y = ctx->ViewportArray[i].Y;
	float half_width = 0.5f * ctx->ViewportArray[i].Width;
	float half_height = 0.5f * ctx->ViewportArray[i].Height;
	double n = ctx->ViewportArray[i].Near;
	double f = ctx->ViewportArray[i].Far;

	scale[0] = half_width;
	translate[0] = half_width + x;
	if (ctx->Transform.ClipOrigin == GL_UPPER_LEFT) {
	scale[1] = -half_height;
	} else {
	scale[1] = half_height;
	}
	translate[1] = half_height + y;

	if (ctx->Transform.ClipDepthMode == GL_NEGATIVE_ONE_TO_ONE) {
	scale[2] = 0.5 * (f - n);
	translate[2] = 0.5 * (n + f);
	} else {
	scale[2] = f - n;
	translate[2] = n;
	}
	}


	static void
	subpixel_precision_bias(struct gl_context *ctx, GLuint xbits, GLuint ybits)
	{
	if (MESA_VERBOSE & VERBOSE_API)
	_mesa_debug(ctx, "glSubpixelPrecisionBiasNV(%u, %u)\n", xbits, ybits);

	FLUSH_VERTICES(ctx, 0);

	ctx->SubpixelPrecisionBias[0] = xbits;
	ctx->SubpixelPrecisionBias[1] = ybits;

	ctx->NewDriverState \|=
	ctx->DriverFlags.NewNvConservativeRasterizationParams;
	}

	void GLAPIENTRY
	_mesa_SubpixelPrecisionBiasNV_no_error(GLuint xbits, GLuint ybits)
	{
	GET_CURRENT_CONTEXT(ctx);

	if (MESA_VERBOSE & VERBOSE_API)
	_mesa_debug(ctx, "glSubpixelPrecisionBiasNV(%u, %u)\n", xbits, ybits);

	subpixel_precision_bias(ctx, xbits, ybits);
	}

	void GLAPIENTRY
	_mesa_SubpixelPrecisionBiasNV(GLuint xbits, GLuint ybits)
	{
	GET_CURRENT_CONTEXT(ctx);

	if (MESA_VERBOSE & VERBOSE_API)
	_mesa_debug(ctx, "glSubpixelPrecisionBiasNV(%u, %u)\n", xbits, ybits);

	ASSERT_OUTSIDE_BEGIN_END(ctx);

	if (!ctx->Extensions.NV_conservative_raster) {
	_mesa_error(ctx, GL_INVALID_OPERATION,
	"glSubpixelPrecisionBiasNV not supported");
	return;
	}

	if (xbits > ctx->Const.MaxSubpixelPrecisionBiasBits) {
	_mesa_error(ctx, GL_INVALID_VALUE, "glSubpixelPrecisionBiasNV");
	return;
	}

	if (ybits > ctx->Const.MaxSubpixelPrecisionBiasBits) {
	_mesa_error(ctx, GL_INVALID_VALUE, "glSubpixelPrecisionBiasNV");
	return;
	}

	subpixel_precision_bias(ctx, xbits, ybits);
	}

	static void
	set_viewport_swizzle(struct gl_context *ctx, GLuint index,
	GLenum swizzlex, GLenum swizzley,
	GLenum swizzlez, GLenum swizzlew)
	{
	struct gl_viewport_attrib *viewport = &ctx->ViewportArray[index];
	if (viewport->SwizzleX == swizzlex &&
	viewport->SwizzleY == swizzley &&
	viewport->SwizzleZ == swizzlez &&
	viewport->SwizzleW == swizzlew)
	return;

	FLUSH_VERTICES(ctx, _NEW_VIEWPORT);
	ctx->NewDriverState \|= ctx->DriverFlags.NewViewport;

	viewport->SwizzleX = swizzlex;
	viewport->SwizzleY = swizzley;
	viewport->SwizzleZ = swizzlez;
	viewport->SwizzleW = swizzlew;
	}

	void GLAPIENTRY
	_mesa_ViewportSwizzleNV_no_error(GLuint index,
	GLenum swizzlex, GLenum swizzley,
	GLenum swizzlez, GLenum swizzlew)
	{
	GET_CURRENT_CONTEXT(ctx);

	if (MESA_VERBOSE & VERBOSE_API)
	_mesa_debug(ctx, "glViewportSwizzleNV(%x, %x, %x, %x)\n",
	swizzlex, swizzley, swizzlez, swizzlew);

	set_viewport_swizzle(ctx, index, swizzlex, swizzley, swizzlez, swizzlew);
	}

	static bool
	verify_viewport_swizzle(GLenum swizzle)
	{
	return swizzle >= GL_VIEWPORT_SWIZZLE_POSITIVE_X_NV &&
	swizzle <= GL_VIEWPORT_SWIZZLE_NEGATIVE_W_NV;
	}

	void GLAPIENTRY
	_mesa_ViewportSwizzleNV(GLuint index,
	GLenum swizzlex, GLenum swizzley,
	GLenum swizzlez, GLenum swizzlew)
	{
	GET_CURRENT_CONTEXT(ctx);

	if (MESA_VERBOSE & VERBOSE_API)
	_mesa_debug(ctx, "glViewportSwizzleNV(%x, %x, %x, %x)\n",
	swizzlex, swizzley, swizzlez, swizzlew);

	if (!ctx->Extensions.NV_viewport_swizzle) {
	_mesa_error(ctx, GL_INVALID_OPERATION,
	"glViewportSwizzleNV not supported");
	return;
	}

	if (index >= ctx->Const.MaxViewports) {
	_mesa_error(ctx, GL_INVALID_VALUE,
	"glViewportSwizzleNV: index (%d) >= MaxViewports (%d)",
	index, ctx->Const.MaxViewports);
	return;
	}

	if (!verify_viewport_swizzle(swizzlex)) {
	_mesa_error(ctx, GL_INVALID_ENUM,
	"glViewportSwizzleNV(swizzlex=%x)", swizzlex);
	return;
	}

	if (!verify_viewport_swizzle(swizzley)) {
	_mesa_error(ctx, GL_INVALID_ENUM,
	"glViewportSwizzleNV(swizzley=%x)", swizzley);
	return;
	}

	if (!verify_viewport_swizzle(swizzlez)) {
	_mesa_error(ctx, GL_INVALID_ENUM,
	"glViewportSwizzleNV(swizzlez=%x)", swizzlez);
	return;
	}

	if (!verify_viewport_swizzle(swizzlew)) {
	_mesa_error(ctx, GL_INVALID_ENUM,
	"glViewportSwizzleNV(swizzlew=%x)", swizzlew);
	return;
	}

	set_viewport_swizzle(ctx, index, swizzlex, swizzley, swizzlez, swizzlew);
	}