src/mesa/drivers/common/meta_generate_mipmap.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.
  */

 /**
  * Meta operations.  Some GL operations can be expressed in terms of
  * other GL operations.  For example, glBlitFramebuffer() can be done
  * with texture mapping and glClear() can be done with polygon rendering.
  *
  * \author Brian Paul
  */

 #include "main/arrayobj.h"
 #include "main/blend.h"
 #include "main/buffers.h"
 #include "main/enums.h"
 #include "main/enable.h"
 #include "main/fbobject.h"
 #include "main/framebuffer.h"
 #include "main/macros.h"
 #include "main/mipmap.h"
 #include "main/teximage.h"
 #include "main/texobj.h"
 #include "main/texparam.h"
 #include "main/varray.h"
 #include "main/viewport.h"
 #include "drivers/common/meta.h"
 #include "program/prog_instruction.h"


 /**
  * Check if the call to _mesa_meta_GenerateMipmap() will require a
  * software fallback.  The fallback path will require that the texture
  * images are mapped.
  * \return GL_TRUE if a fallback is needed, GL_FALSE otherwise
  */
 static bool
 fallback_required(struct gl_context *ctx, GLenum target,
                   struct gl_texture_object *texObj)
 {
    struct gen_mipmap_state *mipmap = &ctx->Meta->Mipmap;
    struct gl_texture_image *baseImage;
    GLuint srcLevel;
    GLenum status;

    /* check for fallbacks */
    if (target == GL_TEXTURE_3D) {
       _mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
                        "glGenerateMipmap() to %s target\n",
                        _mesa_enum_to_string(target));
       return true;
    }

    srcLevel = texObj->BaseLevel;
    baseImage = _mesa_select_tex_image(texObj, target, srcLevel);
    if (!baseImage) {
       _mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
                        "glGenerateMipmap() couldn't find base teximage\n");
       return true;
    }

    if (_mesa_is_format_compressed(baseImage->TexFormat)) {
       _mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
                        "glGenerateMipmap() with %s format\n",
                        _mesa_get_format_name(baseImage->TexFormat));
       return true;
    }

    if (_mesa_get_format_color_encoding(baseImage->TexFormat) == GL_SRGB &&
        !ctx->Extensions.EXT_texture_sRGB_decode) {
       /* The texture format is sRGB but we can't turn off sRGB->linear
        * texture sample conversion.  So we won't be able to generate the
        * right colors when rendering.  Need to use a fallback.
        */
       _mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
                        "glGenerateMipmap() of sRGB texture without "
                        "sRGB decode\n");
       return true;
    }

    /*
     * Test that we can actually render in the texture's format.
     */
    if (mipmap->fb == NULL) {
       mipmap->fb = ctx->Driver.NewFramebuffer(ctx, 0xDEADBEEF);
       if (mipmap->fb == NULL) {
          _mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
                           "glGenerateMipmap() ran out of memory\n");
          return true;
       }
    }

    _mesa_meta_framebuffer_texture_image(ctx, mipmap->fb,
                                         GL_COLOR_ATTACHMENT0, baseImage, 0);

    status = _mesa_check_framebuffer_status(ctx, mipmap->fb);
    if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
       _mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
                        "glGenerateMipmap() got incomplete FBO\n");
       return true;
    }

    return false;
 }

 void
 _mesa_meta_glsl_generate_mipmap_cleanup(struct gl_context *ctx,
                                         struct gen_mipmap_state *mipmap)
 {
    if (mipmap->VAO == 0)
       return;
    _mesa_DeleteVertexArrays(1, &mipmap->VAO);
    mipmap->VAO = 0;
    _mesa_reference_buffer_object(ctx, &mipmap->buf_obj, NULL);
    _mesa_reference_sampler_object(ctx, &mipmap->samp_obj, NULL);
    _mesa_reference_framebuffer(&mipmap->fb, NULL);

    _mesa_meta_blit_shader_table_cleanup(ctx, &mipmap->shaders);
 }


 /**
  * Called via ctx->Driver.GenerateMipmap()
  * Note: We don't yet support 3D textures, or texture borders.
  */
 void
 _mesa_meta_GenerateMipmap(struct gl_context *ctx, GLenum target,
                           struct gl_texture_object *texObj)
 {
    struct gen_mipmap_state *mipmap = &ctx->Meta->Mipmap;
    struct vertex verts[4];
    const GLuint baseLevel = texObj->BaseLevel;
    const GLuint maxLevel = texObj->MaxLevel;
    const GLint maxLevelSave = texObj->MaxLevel;
    const GLboolean genMipmapSave = texObj->GenerateMipmap;
    const GLboolean use_glsl_version = ctx->Extensions.ARB_vertex_shader &&
                                       ctx->Extensions.ARB_fragment_shader;
    GLenum faceTarget;
    GLuint dstLevel;
    struct gl_sampler_object *samp_obj_save = NULL;
    GLint swizzle[4];
    GLboolean swizzleSaved = GL_FALSE;

    /* GLint so the compiler won't complain about type signedness mismatch in
     * the calls to _mesa_texture_parameteriv below.
     */
    static const GLint always_false = GL_FALSE;
    static const GLint always_true = GL_TRUE;

    if (fallback_required(ctx, target, texObj)) {
       _mesa_generate_mipmap(ctx, target, texObj);
       return;
    }

    if (target >= GL_TEXTURE_CUBE_MAP_POSITIVE_X &&
        target <= GL_TEXTURE_CUBE_MAP_NEGATIVE_Z) {
       faceTarget = target;
       target = GL_TEXTURE_CUBE_MAP;
    } else {
       faceTarget = target;
    }

    _mesa_meta_begin(ctx, MESA_META_ALL & ~MESA_META_DRAW_BUFFERS);
    _mesa_ColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
    _mesa_Disable(GL_DITHER);

    /* Choose between glsl version and fixed function version of
     * GenerateMipmap function.
     */
    if (use_glsl_version) {
       _mesa_meta_setup_vertex_objects(ctx, &mipmap->VAO, &mipmap->buf_obj, true,
                                       2, 4, 0);
       _mesa_meta_setup_blit_shader(ctx, target, false, &mipmap->shaders);
    } else {
       _mesa_meta_setup_ff_tnl_for_blit(ctx, &mipmap->VAO, &mipmap->buf_obj, 3);
       _mesa_set_enable(ctx, target, GL_TRUE);
    }

    _mesa_reference_sampler_object(ctx, &samp_obj_save,
                                   ctx->Texture.Unit[ctx->Texture.CurrentUnit].Sampler);

    /* We may have been called from glGenerateTextureMipmap with CurrentUnit
     * still set to 0, so we don't know when we can skip binding the texture.
     * Assume that _mesa_BindTexture will be fast if we're rebinding the same
     * texture.
     */
    _mesa_BindTexture(target, texObj->Name);

    if (mipmap->samp_obj == NULL) {
       mipmap->samp_obj =  ctx->Driver.NewSamplerObject(ctx, 0xDEADBEEF);
       if (mipmap->samp_obj == NULL) {
          /* This is a bit lazy.  Flag out of memory, and then don't bother to
           * clean up.  Once out of memory is flagged, the only realistic next
           * move is to destroy the context.  That will trigger all the right
           * clean up.
           */
          _mesa_error(ctx, GL_OUT_OF_MEMORY, "glGenerateMipmap");
          return;
       }

       _mesa_set_sampler_filters(ctx, mipmap->samp_obj, GL_LINEAR_MIPMAP_LINEAR,
                                 GL_LINEAR);
       _mesa_set_sampler_wrap(ctx, mipmap->samp_obj, GL_CLAMP_TO_EDGE,
                              GL_CLAMP_TO_EDGE, GL_CLAMP_TO_EDGE);
    }

    if (ctx->Extensions.EXT_texture_sRGB_decode) {
       const struct gl_texture_image *baseImage =
          _mesa_select_tex_image(texObj, target, texObj->BaseLevel);
       const bool srgb =
          _mesa_get_format_color_encoding(baseImage->TexFormat) == GL_SRGB;

       _mesa_set_sampler_srgb_decode(ctx, mipmap->samp_obj,
                                     srgb ? GL_DECODE_EXT : GL_SKIP_DECODE_EXT);
       _mesa_set_framebuffer_srgb(ctx, srgb);
    }

    _mesa_bind_sampler(ctx, ctx->Texture.CurrentUnit, mipmap->samp_obj);

    assert(mipmap->fb != NULL);
    _mesa_bind_framebuffers(ctx, mipmap->fb, mipmap->fb);

    _mesa_texture_parameteriv(ctx, texObj, GL_GENERATE_MIPMAP, &always_false, false);

    if (texObj->_Swizzle != SWIZZLE_NOOP) {
       static const GLint swizzleNoop[4] = { GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA };
       memcpy(swizzle, texObj->Swizzle, sizeof(swizzle));
       swizzleSaved = GL_TRUE;
       _mesa_texture_parameteriv(ctx, texObj, GL_TEXTURE_SWIZZLE_RGBA,
                                 swizzleNoop, false);
    }

    /* Silence valgrind warnings about reading uninitialized stack. */
    memset(verts, 0, sizeof(verts));

    /* setup vertex positions */
    verts[0].x = -1.0F;
    verts[0].y = -1.0F;
    verts[1].x =  1.0F;
    verts[1].y = -1.0F;
    verts[2].x =  1.0F;
    verts[2].y =  1.0F;
    verts[3].x = -1.0F;
    verts[3].y =  1.0F;

    /* texture is already locked, unlock now */
    _mesa_unlock_texture(ctx, texObj);

    _mesa_prepare_mipmap_levels(ctx, texObj, baseLevel, maxLevel);

    for (dstLevel = baseLevel + 1; dstLevel <= maxLevel; dstLevel++) {
       const struct gl_texture_image *srcImage;
       struct gl_texture_image *dstImage;
       const GLuint srcLevel = dstLevel - 1;
       GLuint layer;
       GLsizei srcWidth, srcHeight, srcDepth;
       GLsizei dstWidth, dstHeight, dstDepth;

       srcImage = _mesa_select_tex_image(texObj, faceTarget, srcLevel);
       assert(srcImage->Border == 0);

       /* src size */
       srcWidth = srcImage->Width;
       if (target == GL_TEXTURE_1D_ARRAY) {
          srcHeight = 1;
          srcDepth = srcImage->Height;
       } else {
          srcHeight = srcImage->Height;
          srcDepth = srcImage->Depth;
       }

       /* new dst size */
       dstWidth = minify(srcWidth, 1);
       dstHeight = minify(srcHeight, 1);
       dstDepth = target == GL_TEXTURE_3D ? minify(srcDepth, 1) : srcDepth;

       if (dstWidth == srcWidth &&
           dstHeight == srcHeight &&
           dstDepth == srcDepth) {
          /* all done */
          break;
       }

       /* Allocate storage for the destination mipmap image(s) */

       /* Set MaxLevel large enough to hold the new level when we allocate it */
       _mesa_texture_parameteriv(ctx, texObj, GL_TEXTURE_MAX_LEVEL,
                                 (GLint *) &dstLevel, false);

       dstImage = _mesa_select_tex_image(texObj, faceTarget, dstLevel);

       /* All done.  We either ran out of memory or we would go beyond the last
        * valid level of an immutable texture if we continued.
        */
       if (dstImage == NULL)
          break;

       /* limit minification to src level */
       _mesa_texture_parameteriv(ctx, texObj, GL_TEXTURE_MAX_LEVEL,
                                 (GLint *) &srcLevel, false);

       /* setup viewport */
       _mesa_set_viewport(ctx, 0, 0, 0, dstWidth, dstHeight);
       _mesa_DrawBuffer(GL_COLOR_ATTACHMENT0);

       for (layer = 0; layer < dstDepth; ++layer) {
          /* Setup texture coordinates */
          _mesa_meta_setup_texture_coords(faceTarget,
                                          layer,
                                          0, 0, /* xoffset, yoffset */
                                          srcWidth, srcHeight, /* img size */
                                          srcWidth, srcHeight, srcDepth,
                                          verts[0].tex,
                                          verts[1].tex,
                                          verts[2].tex,
                                          verts[3].tex);

          /* upload vertex data */
          _mesa_buffer_data(ctx, mipmap->buf_obj, GL_NONE, sizeof(verts), verts,
                            GL_DYNAMIC_DRAW, __func__);

          _mesa_meta_framebuffer_texture_image(ctx, ctx->DrawBuffer,
                                               GL_COLOR_ATTACHMENT0, dstImage,
                                               layer);

          /* sanity check */
          if (_mesa_check_framebuffer_status(ctx, ctx->DrawBuffer) !=
              GL_FRAMEBUFFER_COMPLETE) {
             _mesa_problem(ctx, "Unexpected incomplete framebuffer in "
                           "_mesa_meta_GenerateMipmap()");
             break;
          }

          assert(dstWidth == ctx->DrawBuffer->Width);
          if (target == GL_TEXTURE_1D_ARRAY) {
             assert(dstHeight == 1);
          } else {
             assert(dstHeight == ctx->DrawBuffer->Height);
          }

          _mesa_DrawArrays(GL_TRIANGLE_FAN, 0, 4);
       }
    }

    _mesa_lock_texture(ctx, texObj); /* relock */

    _mesa_bind_sampler(ctx, ctx->Texture.CurrentUnit, samp_obj_save);
    _mesa_reference_sampler_object(ctx, &samp_obj_save, NULL);

    _mesa_meta_end(ctx);

    _mesa_texture_parameteriv(ctx, texObj, GL_TEXTURE_MAX_LEVEL, &maxLevelSave,
                              false);
    if (genMipmapSave)
       _mesa_texture_parameteriv(ctx, texObj, GL_GENERATE_MIPMAP, &always_true,
                                 false);
    if (swizzleSaved)
       _mesa_texture_parameteriv(ctx, texObj, GL_TEXTURE_SWIZZLE_RGBA, swizzle,
                                 false);
 }
	/*
	* 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.
	*/

	/**
	* Meta operations. Some GL operations can be expressed in terms of
	* other GL operations. For example, glBlitFramebuffer() can be done
	* with texture mapping and glClear() can be done with polygon rendering.
	*
	* \author Brian Paul
	*/

	#include "main/arrayobj.h"
	#include "main/blend.h"
	#include "main/buffers.h"
	#include "main/enums.h"
	#include "main/enable.h"
	#include "main/fbobject.h"
	#include "main/framebuffer.h"
	#include "main/macros.h"
	#include "main/mipmap.h"
	#include "main/teximage.h"
	#include "main/texobj.h"
	#include "main/texparam.h"
	#include "main/varray.h"
	#include "main/viewport.h"
	#include "drivers/common/meta.h"
	#include "program/prog_instruction.h"


	/**
	* Check if the call to _mesa_meta_GenerateMipmap() will require a
	* software fallback. The fallback path will require that the texture
	* images are mapped.
	* \return GL_TRUE if a fallback is needed, GL_FALSE otherwise
	*/
	static bool
	fallback_required(struct gl_context *ctx, GLenum target,
	struct gl_texture_object *texObj)
	{
	struct gen_mipmap_state *mipmap = &ctx->Meta->Mipmap;
	struct gl_texture_image *baseImage;
	GLuint srcLevel;
	GLenum status;

	/* check for fallbacks */
	if (target == GL_TEXTURE_3D) {
	_mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
	"glGenerateMipmap() to %s target\n",
	_mesa_enum_to_string(target));
	return true;
	}

	srcLevel = texObj->BaseLevel;
	baseImage = _mesa_select_tex_image(texObj, target, srcLevel);
	if (!baseImage) {
	_mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
	"glGenerateMipmap() couldn't find base teximage\n");
	return true;
	}

	if (_mesa_is_format_compressed(baseImage->TexFormat)) {
	_mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
	"glGenerateMipmap() with %s format\n",
	_mesa_get_format_name(baseImage->TexFormat));
	return true;
	}

	if (_mesa_get_format_color_encoding(baseImage->TexFormat) == GL_SRGB &&
	!ctx->Extensions.EXT_texture_sRGB_decode) {
	/* The texture format is sRGB but we can't turn off sRGB->linear
	* texture sample conversion. So we won't be able to generate the
	* right colors when rendering. Need to use a fallback.
	*/
	_mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
	"glGenerateMipmap() of sRGB texture without "
	"sRGB decode\n");
	return true;
	}

	/*
	* Test that we can actually render in the texture's format.
	*/
	if (mipmap->fb == NULL) {
	mipmap->fb = ctx->Driver.NewFramebuffer(ctx, 0xDEADBEEF);
	if (mipmap->fb == NULL) {
	_mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
	"glGenerateMipmap() ran out of memory\n");
	return true;
	}
	}

	_mesa_meta_framebuffer_texture_image(ctx, mipmap->fb,
	GL_COLOR_ATTACHMENT0, baseImage, 0);

	status = _mesa_check_framebuffer_status(ctx, mipmap->fb);
	if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
	_mesa_perf_debug(ctx, MESA_DEBUG_SEVERITY_HIGH,
	"glGenerateMipmap() got incomplete FBO\n");
	return true;
	}

	return false;
	}

	void
	_mesa_meta_glsl_generate_mipmap_cleanup(struct gl_context *ctx,
	struct gen_mipmap_state *mipmap)
	{
	if (mipmap->VAO == 0)
	return;
	_mesa_DeleteVertexArrays(1, &mipmap->VAO);
	mipmap->VAO = 0;
	_mesa_reference_buffer_object(ctx, &mipmap->buf_obj, NULL);
	_mesa_reference_sampler_object(ctx, &mipmap->samp_obj, NULL);
	_mesa_reference_framebuffer(&mipmap->fb, NULL);

	_mesa_meta_blit_shader_table_cleanup(ctx, &mipmap->shaders);
	}


	/**
	* Called via ctx->Driver.GenerateMipmap()
	* Note: We don't yet support 3D textures, or texture borders.
	*/
	void
	_mesa_meta_GenerateMipmap(struct gl_context *ctx, GLenum target,
	struct gl_texture_object *texObj)
	{
	struct gen_mipmap_state *mipmap = &ctx->Meta->Mipmap;
	struct vertex verts[4];
	const GLuint baseLevel = texObj->BaseLevel;
	const GLuint maxLevel = texObj->MaxLevel;
	const GLint maxLevelSave = texObj->MaxLevel;
	const GLboolean genMipmapSave = texObj->GenerateMipmap;
	const GLboolean use_glsl_version = ctx->Extensions.ARB_vertex_shader &&
	ctx->Extensions.ARB_fragment_shader;
	GLenum faceTarget;
	GLuint dstLevel;
	struct gl_sampler_object *samp_obj_save = NULL;
	GLint swizzle[4];
	GLboolean swizzleSaved = GL_FALSE;

	/* GLint so the compiler won't complain about type signedness mismatch in
	* the calls to _mesa_texture_parameteriv below.
	*/
	static const GLint always_false = GL_FALSE;
	static const GLint always_true = GL_TRUE;

	if (fallback_required(ctx, target, texObj)) {
	_mesa_generate_mipmap(ctx, target, texObj);
	return;
	}

	if (target >= GL_TEXTURE_CUBE_MAP_POSITIVE_X &&
	target <= GL_TEXTURE_CUBE_MAP_NEGATIVE_Z) {
	faceTarget = target;
	target = GL_TEXTURE_CUBE_MAP;
	} else {
	faceTarget = target;
	}

	_mesa_meta_begin(ctx, MESA_META_ALL & ~MESA_META_DRAW_BUFFERS);
	_mesa_ColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
	_mesa_Disable(GL_DITHER);

	/* Choose between glsl version and fixed function version of
	* GenerateMipmap function.
	*/
	if (use_glsl_version) {
	_mesa_meta_setup_vertex_objects(ctx, &mipmap->VAO, &mipmap->buf_obj, true,
	2, 4, 0);
	_mesa_meta_setup_blit_shader(ctx, target, false, &mipmap->shaders);
	} else {
	_mesa_meta_setup_ff_tnl_for_blit(ctx, &mipmap->VAO, &mipmap->buf_obj, 3);
	_mesa_set_enable(ctx, target, GL_TRUE);
	}

	_mesa_reference_sampler_object(ctx, &samp_obj_save,
	ctx->Texture.Unit[ctx->Texture.CurrentUnit].Sampler);

	/* We may have been called from glGenerateTextureMipmap with CurrentUnit
	* still set to 0, so we don't know when we can skip binding the texture.
	* Assume that _mesa_BindTexture will be fast if we're rebinding the same
	* texture.
	*/
	_mesa_BindTexture(target, texObj->Name);

	if (mipmap->samp_obj == NULL) {
	mipmap->samp_obj = ctx->Driver.NewSamplerObject(ctx, 0xDEADBEEF);
	if (mipmap->samp_obj == NULL) {
	/* This is a bit lazy. Flag out of memory, and then don't bother to
	* clean up. Once out of memory is flagged, the only realistic next
	* move is to destroy the context. That will trigger all the right
	* clean up.
	*/
	_mesa_error(ctx, GL_OUT_OF_MEMORY, "glGenerateMipmap");
	return;
	}

	_mesa_set_sampler_filters(ctx, mipmap->samp_obj, GL_LINEAR_MIPMAP_LINEAR,
	GL_LINEAR);
	_mesa_set_sampler_wrap(ctx, mipmap->samp_obj, GL_CLAMP_TO_EDGE,
	GL_CLAMP_TO_EDGE, GL_CLAMP_TO_EDGE);
	}

	if (ctx->Extensions.EXT_texture_sRGB_decode) {
	const struct gl_texture_image *baseImage =
	_mesa_select_tex_image(texObj, target, texObj->BaseLevel);
	const bool srgb =
	_mesa_get_format_color_encoding(baseImage->TexFormat) == GL_SRGB;

	_mesa_set_sampler_srgb_decode(ctx, mipmap->samp_obj,
	srgb ? GL_DECODE_EXT : GL_SKIP_DECODE_EXT);
	_mesa_set_framebuffer_srgb(ctx, srgb);
	}

	_mesa_bind_sampler(ctx, ctx->Texture.CurrentUnit, mipmap->samp_obj);

	assert(mipmap->fb != NULL);
	_mesa_bind_framebuffers(ctx, mipmap->fb, mipmap->fb);

	_mesa_texture_parameteriv(ctx, texObj, GL_GENERATE_MIPMAP, &always_false, false);

	if (texObj->_Swizzle != SWIZZLE_NOOP) {
	static const GLint swizzleNoop[4] = { GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA };
	memcpy(swizzle, texObj->Swizzle, sizeof(swizzle));
	swizzleSaved = GL_TRUE;
	_mesa_texture_parameteriv(ctx, texObj, GL_TEXTURE_SWIZZLE_RGBA,
	swizzleNoop, false);
	}

	/* Silence valgrind warnings about reading uninitialized stack. */
	memset(verts, 0, sizeof(verts));

	/* setup vertex positions */
	verts[0].x = -1.0F;
	verts[0].y = -1.0F;
	verts[1].x = 1.0F;
	verts[1].y = -1.0F;
	verts[2].x = 1.0F;
	verts[2].y = 1.0F;
	verts[3].x = -1.0F;
	verts[3].y = 1.0F;

	/* texture is already locked, unlock now */
	_mesa_unlock_texture(ctx, texObj);

	_mesa_prepare_mipmap_levels(ctx, texObj, baseLevel, maxLevel);

	for (dstLevel = baseLevel + 1; dstLevel <= maxLevel; dstLevel++) {
	const struct gl_texture_image *srcImage;
	struct gl_texture_image *dstImage;
	const GLuint srcLevel = dstLevel - 1;
	GLuint layer;
	GLsizei srcWidth, srcHeight, srcDepth;
	GLsizei dstWidth, dstHeight, dstDepth;

	srcImage = _mesa_select_tex_image(texObj, faceTarget, srcLevel);
	assert(srcImage->Border == 0);

	/* src size */
	srcWidth = srcImage->Width;
	if (target == GL_TEXTURE_1D_ARRAY) {
	srcHeight = 1;
	srcDepth = srcImage->Height;
	} else {
	srcHeight = srcImage->Height;
	srcDepth = srcImage->Depth;
	}

	/* new dst size */
	dstWidth = minify(srcWidth, 1);
	dstHeight = minify(srcHeight, 1);
	dstDepth = target == GL_TEXTURE_3D ? minify(srcDepth, 1) : srcDepth;

	if (dstWidth == srcWidth &&
	dstHeight == srcHeight &&
	dstDepth == srcDepth) {
	/* all done */
	break;
	}

	/* Allocate storage for the destination mipmap image(s) */

	/* Set MaxLevel large enough to hold the new level when we allocate it */
	_mesa_texture_parameteriv(ctx, texObj, GL_TEXTURE_MAX_LEVEL,
	(GLint *) &dstLevel, false);

	dstImage = _mesa_select_tex_image(texObj, faceTarget, dstLevel);

	/* All done. We either ran out of memory or we would go beyond the last
	* valid level of an immutable texture if we continued.
	*/
	if (dstImage == NULL)
	break;

	/* limit minification to src level */
	_mesa_texture_parameteriv(ctx, texObj, GL_TEXTURE_MAX_LEVEL,
	(GLint *) &srcLevel, false);

	/* setup viewport */
	_mesa_set_viewport(ctx, 0, 0, 0, dstWidth, dstHeight);
	_mesa_DrawBuffer(GL_COLOR_ATTACHMENT0);

	for (layer = 0; layer < dstDepth; ++layer) {
	/* Setup texture coordinates */
	_mesa_meta_setup_texture_coords(faceTarget,
	layer,
	0, 0, /* xoffset, yoffset */
	srcWidth, srcHeight, /* img size */
	srcWidth, srcHeight, srcDepth,
	verts[0].tex,
	verts[1].tex,
	verts[2].tex,
	verts[3].tex);

	/* upload vertex data */
	_mesa_buffer_data(ctx, mipmap->buf_obj, GL_NONE, sizeof(verts), verts,
	GL_DYNAMIC_DRAW, __func__);

	_mesa_meta_framebuffer_texture_image(ctx, ctx->DrawBuffer,
	GL_COLOR_ATTACHMENT0, dstImage,
	layer);

	/* sanity check */
	if (_mesa_check_framebuffer_status(ctx, ctx->DrawBuffer) !=
	GL_FRAMEBUFFER_COMPLETE) {
	_mesa_problem(ctx, "Unexpected incomplete framebuffer in "
	"_mesa_meta_GenerateMipmap()");
	break;
	}

	assert(dstWidth == ctx->DrawBuffer->Width);
	if (target == GL_TEXTURE_1D_ARRAY) {
	assert(dstHeight == 1);
	} else {
	assert(dstHeight == ctx->DrawBuffer->Height);
	}

	_mesa_DrawArrays(GL_TRIANGLE_FAN, 0, 4);
	}
	}

	_mesa_lock_texture(ctx, texObj); /* relock */

	_mesa_bind_sampler(ctx, ctx->Texture.CurrentUnit, samp_obj_save);
	_mesa_reference_sampler_object(ctx, &samp_obj_save, NULL);

	_mesa_meta_end(ctx);

	_mesa_texture_parameteriv(ctx, texObj, GL_TEXTURE_MAX_LEVEL, &maxLevelSave,
	false);
	if (genMipmapSave)
	_mesa_texture_parameteriv(ctx, texObj, GL_GENERATE_MIPMAP, &always_true,
	false);
	if (swizzleSaved)
	_mesa_texture_parameteriv(ctx, texObj, GL_TEXTURE_SWIZZLE_RGBA, swizzle,
	false);
	}