| /* |
| * Copyright 2023 Google LLC |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #include "src/gpu/graphite/render/PerEdgeAAQuadRenderStep.h" |
| |
| #include "src/base/SkVx.h" |
| #include "src/core/SkRRectPriv.h" |
| #include "src/gpu/graphite/DrawParams.h" |
| #include "src/gpu/graphite/DrawWriter.h" |
| #include "src/gpu/graphite/render/CommonDepthStencilSettings.h" |
| |
| // This RenderStep is specialized to draw filled rectangles with per-edge AA. |
| // |
| // Each of these "primitives" is represented by a single instance. The instance attributes are |
| // flexible enough to describe any of the above shapes without relying on uniforms to define its |
| // operation. The attributes encode shape as follows: |
| // |
| // float4 xRadiiOrFlags - if any components is > 0, the instance represents a filled round rect |
| // with elliptical corners and these values specify the X radii in top-left CW order. |
| // Otherwise, if .x < -1, the instance represents a stroked or hairline [round] rect or line, |
| // where .y differentiates hairline vs. stroke. If .y is negative, then it is a hairline [round] |
| // rect and xRadiiOrFlags stores (-2 - X radii); if .y is zero, it is a regular stroked [round] |
| // rect; if .y is positive, then it is a stroked *or* hairline line. For .y >= 0, .z holds the |
| // stroke radius and .w stores the join limit (matching StrokeStyle's conventions). |
| // Lastly, if -1 <= .x <= 0, it's a filled quadrilateral with per-edge AA defined by each by the |
| // component: aa != 0. |
| // float4 radiiOrQuadXs - if in filled round rect or hairline [round] rect mode, these values |
| // provide the Y radii in top-left CW order. If in stroked [round] rect mode, these values |
| // provide the circular corner radii (same order). Otherwise, when in per-edge quad mode, these |
| // values provide the X coordinates of the quadrilateral (same order). |
| // float4 ltrbOrQuadYs - if in filled round rect mode or stroked [round] rect mode, these values |
| // define the LTRB edge coordinates of the rectangle surrounding the round rect (or the |
| // rect itself when the radii are 0s). In stroked line mode, LTRB is treated as (x0,y0) and |
| // (x1,y1) that defines the line. Otherwise, in per-edge quad mode, these values provide |
| // the Y coordinates of the quadrilateral. |
| // |
| // From the other direction, shapes produce instance values like: |
| // - filled rect: [-1 -1 -1 -1] [L R R L] [T T B B] |
| // - stroked rect: [-2 0 stroke join] [0 0 0 0] [L T R B] |
| // - hairline rect: [-2 -2 -2 -2] [0 0 0 0] [L T R B] |
| // - filled rrect: [xRadii(tl,tr,br,bl)] [yRadii(tl,tr,br,bl)] [L T R B] |
| // - stroked rrect: [-2 0 stroke join] [radii(tl,tr,br,bl)] [L T R B] |
| // - hairline rrect: [-2-xRadii(tl,tr,br,bl)] [radii(tl,tr,br,bl)] [L T R B] |
| // - filled line: N/A, discarded higher in the stack |
| // - stroked line: [-2 1 stroke cap] [0 0 0 0] [x0,y0,x1,y1] |
| // - hairline line: [-2 1 0 1] [0 0 0 0] [x0,y0,x1,y1] |
| // - per-edge quad: [aa(t,r,b,l) ? -1 : 0] [xs(tl,tr,br,bl)] [ys(tl,tr,br,bl)] |
| // |
| // This encoding relies on the fact that a valid SkRRect with all x radii equal to 0 must have |
| // y radii equal to 0 (so it's a rectangle and we can treat it as a quadrilateral with |
| // all edges AA'ed). This avoids other encodings' inability to represent a quad with all edges |
| // anti-aliased (e.g. checking for negatives in xRadiiOrFlags to turn on per-edge mode). |
| // |
| // From this encoding, data can be unpacked for each corner, which are equivalent under |
| // rotational symmetry. A corner can have an outer curve, be mitered, or be beveled. It can |
| // have an inner curve, an inner miter, or fill the interior. Per-edge quads are always mitered |
| // and fill the interior, but the vertices are placed such that the edge coverage ramps can |
| // collapse to 0 area on non-AA edges. |
| // |
| // The vertices that describe each corner are placed so that edges, miters, and bevels calculate |
| // coverage by interpolating a varying and then clamping in the fragment shader. Triangles that |
| // cover the inner and outer curves calculate distance to the curve within the fragment shader. |
| // |
| // See https://docs.google.com/presentation/d/1MCPstNsSlDBhR8CrsJo0r-cZNbu-sEJEvU9W94GOJoY/edit?usp=sharing |
| // for diagrams and explanation of how the geometry is defined. |
| // |
| // PerEdgeAAQuadRenderStep uses the common technique of approximating distance to the level set by |
| // one expansion of the Taylor's series for the level set's equation. Given a level set function |
| // C(x,y), this amounts to calculating C(px,py)/|∇C(px,py)|. For the straight edges the level set |
| // is linear and calculated in the vertex shader and then interpolated exactly over the rectangle. |
| // This provides distances to all four exterior edges within the fragment shader and allows it to |
| // reconstruct a relative position per elliptical corner. Unfortunately this requires the fragment |
| // shader to calculate the length of the gradient for straight edges instead of interpolating |
| // exact device-space distance. |
| // |
| // All four corner radii are potentially evaluated by the fragment shader although each corner's |
| // coverage is only calculated when the pixel is within the bounding box of its quadrant. For fills |
| // and simple strokes it's theoretically valid to have each pixel calculate a single corner's |
| // coverage that was controlled via the vertex shader. However, testing all four corners is |
| // necessary in order to correctly handle self-intersecting stroke interiors. Similarly, all four |
| // edges must be evaluated in order to handle extremely thin shapes; whereas often you could get |
| // away with tracking a single edge distance per pixel. |
| // |
| // Analytic derivatives are used so that a single pipeline can be used regardless of HW derivative |
| // support or for geometry that would prove difficult for forward differencing. The device-space |
| // gradient for ellipses is calculated per-pixel by transforming a per-pixel local gradient vector |
| // with the Jacobian of the inverse local-to-device transform: |
| // |
| // (px,py) is the projected point of (u,v) transformed by a 3x3 matrix, M: |
| // [x(u,v) / w(u,v)] [x] [m00 m01 m02] [u] |
| // (px,py) = [y(u,v) / w(u,v)] where [y] = [m10 m11 m12]X[v] = M*(u,v,1) |
| // [w] [m20 m21 m22] [1] |
| // |
| // C(px,py) can be defined in terms of a local Cl(u,v) as C(px,py) = Cl(p^-1(px,py)), where p^-1 = |
| // |
| // [x'(px,py) / w'(px,py)] [x'] [m00' m01' * m02'] [px] |
| // (u,v) = [y'(px,py) / w'(px,py)] where [y'] = [m10' m11' * m12']X[py] = M^-1*(px,py,0,1) |
| // [w'] [m20' m21' * m22'] [ 1] |
| // |
| // Note that if the 3x3 M was arrived by dropping the 3rd row and column from a 4x4 since we assume |
| // a local 3rd coordinate of 0, M^-1 is not equal to the 4x4 inverse with dropped rows and columns. |
| // |
| // Using the chain rule, then ∇C(px,py) |
| // = ∇Cl(u,v)X[1/w'(px,py) 0 -x'(px,py)/w'(px,py)^2] [m00' m01'] |
| // [ 0 1/w'(px,py) -y'(px,py)/w'(px,py)^2]X[m10' m11'] |
| // [m20' m21'] |
| // |
| // = 1/w'(px,py)*∇Cl(u,v)X[1 0 -x'(px,py)/w'(px,py)] [m00' m01'] |
| // [0 1 -y'(px,py)/w'(px,py)]X[m10' m11'] |
| // [m20' m21'] |
| // |
| // = w(u,v)*∇Cl(u,v)X[1 0 0 -u] [m00' m01'] |
| // [0 1 0 -v]X[m10' m11'] |
| // [m20' m21'] |
| // |
| // = w(u,v)*∇Cl(u,v)X[m00'-m20'u m01'-m21'u] |
| // [m10'-m20'v m11'-m21'v] |
| // |
| // The vertex shader calculates the rightmost 2x2 matrix and interpolates it across the shape since |
| // each component is linear in (u,v). ∇Cl(u,v) is evaluated per pixel in the fragment shader and |
| // depends on which corner and edge being evaluated. w(u,v) is the device-space W coordinate, so |
| // its reciprocal is provided in sk_FragCoord.w. |
| namespace skgpu::graphite { |
| |
| using AAFlags = EdgeAAQuad::Flags; |
| |
| static skvx::float4 load_x_radii(const SkRRect& rrect) { |
| return skvx::float4{rrect.radii(SkRRect::kUpperLeft_Corner).fX, |
| rrect.radii(SkRRect::kUpperRight_Corner).fX, |
| rrect.radii(SkRRect::kLowerRight_Corner).fX, |
| rrect.radii(SkRRect::kLowerLeft_Corner).fX}; |
| } |
| static skvx::float4 load_y_radii(const SkRRect& rrect) { |
| return skvx::float4{rrect.radii(SkRRect::kUpperLeft_Corner).fY, |
| rrect.radii(SkRRect::kUpperRight_Corner).fY, |
| rrect.radii(SkRRect::kLowerRight_Corner).fY, |
| rrect.radii(SkRRect::kLowerLeft_Corner).fY}; |
| } |
| |
| static float local_aa_radius(const Transform& t, const SkV2& p) { |
| // TODO: This should be the logic for Transform::scaleFactor() |
| // [m00 m01 * m03] [f(u,v)] |
| // Assuming M = [m10 m11 * m13], define the projected p'(u,v) = [g(u,v)] where |
| // [ * * * * ] |
| // [m30 m31 * m33] |
| // [x] [u] |
| // f(u,v) = x(u,v) / w(u,v), g(u,v) = y(u,v) / w(u,v) and [y] = M*[v] |
| // [*] = [0] |
| // [w] [1] |
| // |
| // x(u,v) = m00*u + m01*v + m03 |
| // y(u,v) = m10*u + m11*v + m13 |
| // w(u,v) = m30*u + m31*v + m33 |
| // |
| // dx/du = m00, dx/dv = m01, |
| // dy/du = m10, dy/dv = m11 |
| // dw/du = m30, dw/dv = m31 |
| // |
| // df/du = (dx/du*w - x*dw/du)/w^2 = (m00*w - m30*x)/w^2 = (m00 - m30*f)/w |
| // df/dv = (dx/dv*w - x*dw/dv)/w^2 = (m01*w - m31*x)/w^2 = (m01 - m31*f)/w |
| // dg/du = (dy/du*w - y*dw/du)/w^2 = (m10*w - m30*y)/w^2 = (m10 - m30*g)/w |
| // dg/dv = (dy/dv*w - y*dw/du)/w^2 = (m11*w - m31*y)/w^2 = (m11 - m31*g)/w |
| // |
| // Singular values of [df/du df/dv] define perspective correct minimum and maximum scale factors |
| // [dg/du dg/dv] |
| // for M evaluated at (u,v) |
| const SkM44& matrix = t.matrix(); |
| SkV4 devP = matrix.map(p.x, p.y, 0.f, 1.f); |
| |
| const float dxdu = matrix.rc(0,0); |
| const float dxdv = matrix.rc(0,1); |
| const float dydu = matrix.rc(1,0); |
| const float dydv = matrix.rc(1,1); |
| const float dwdu = matrix.rc(3,0); |
| const float dwdv = matrix.rc(3,1); |
| |
| float invW2 = sk_ieee_float_divide(1.f, (devP.w * devP.w)); |
| // non-persp has invW2 = 1, devP.w = 1, dwdu = 0, dwdv = 0 |
| float dfdu = (devP.w*dxdu - devP.x*dwdu) * invW2; // non-persp -> dxdu -> m00 |
| float dfdv = (devP.w*dxdv - devP.x*dwdv) * invW2; // non-persp -> dxdv -> m01 |
| float dgdu = (devP.w*dydu - devP.y*dwdu) * invW2; // non-persp -> dydu -> m10 |
| float dgdv = (devP.w*dydv - devP.y*dwdv) * invW2; // non-persp -> dydv -> m11 |
| |
| // no-persp, these are the singular values of [m00,m01][m10,m11], which is just the upper 2x2 |
| // and equivalent to SkMatrix::getMinmaxScales(). |
| float s1 = dfdu*dfdu + dfdv*dfdv + dgdu*dgdu + dgdv*dgdv; |
| |
| float e = dfdu*dfdu + dfdv*dfdv - dgdu*dgdu - dgdv*dgdv; |
| float f = dfdu*dgdu + dfdv*dgdv; |
| float s2 = SkScalarSqrt(e*e + 4*f*f); |
| |
| float singular1 = SkScalarSqrt(0.5f * (s1 + s2)); |
| float singular2 = SkScalarSqrt(0.5f * (s1 - s2)); |
| |
| // singular1 and 2 represent the minimum and maximum scale factors at that transformed point. |
| // Moving 1 from 'p' before transforming will move at least minimum and at most maximum from |
| // the transformed point. Thus moving between [1/max, 1/min] pre-transformation means post |
| // transformation moves between [1,max/min] so using 1/min as the local AA radius ensures that |
| // the post-transformed point is at least 1px away from the original. |
| float aaRadius = sk_ieee_float_divide(1.f, std::min(singular1, singular2)); |
| if (sk_float_isfinite(aaRadius)) { |
| return aaRadius; |
| } else { |
| // Treat NaNs and infinities as +inf, which will always trigger the inset self-intersection |
| // logic that snaps inner vertices to the center instead of insetting by the local AA radius |
| return SK_FloatInfinity; |
| } |
| } |
| |
| static float local_aa_radius(const Transform& t, const Rect& bounds) { |
| // Use the maximum radius of the 4 corners so that every local vertex uses the same offset |
| // even if it's more conservative on some corners (when the min/max scale isn't constant due |
| // to perspective). |
| if (t.type() < Transform::Type::kProjection) { |
| // Scale factors are constant, so the point doesn't really matter |
| return local_aa_radius(t, SkV2{0.f, 0.f}); |
| } else { |
| // TODO can we share calculation here? |
| float tl = local_aa_radius(t, SkV2{bounds.left(), bounds.top()}); |
| float tr = local_aa_radius(t, SkV2{bounds.right(), bounds.top()}); |
| float br = local_aa_radius(t, SkV2{bounds.right(), bounds.bot()}); |
| float bl = local_aa_radius(t, SkV2{bounds.left(), bounds.bot()}); |
| return std::max(std::max(tl, tr), std::max(bl, br)); |
| } |
| } |
| |
| static bool opposite_insets_intersect(const SkRRect& rrect, float strokeRadius, float aaRadius) { |
| // One AA inset per side |
| const float maxInset = strokeRadius + 2.f * aaRadius; |
| return // Horizontal insets would intersect opposite corner's curve |
| maxInset >= rrect.width() - rrect.radii(SkRRect::kLowerLeft_Corner).fX || |
| maxInset >= rrect.width() - rrect.radii(SkRRect::kLowerRight_Corner).fX || |
| maxInset >= rrect.width() - rrect.radii(SkRRect::kUpperLeft_Corner).fX || |
| maxInset >= rrect.width() - rrect.radii(SkRRect::kUpperRight_Corner).fX || |
| // Vertical insets would intersect opposite corner's curve |
| maxInset >= rrect.height() - rrect.radii(SkRRect::kLowerLeft_Corner).fY || |
| maxInset >= rrect.height() - rrect.radii(SkRRect::kLowerRight_Corner).fY || |
| maxInset >= rrect.height() - rrect.radii(SkRRect::kUpperLeft_Corner).fY || |
| maxInset >= rrect.height() - rrect.radii(SkRRect::kUpperRight_Corner).fY; |
| } |
| |
| static bool opposite_insets_intersect(const Rect& rect, float strokeRadius, float aaRadius) { |
| return any(rect.size() <= 2.f * (strokeRadius + aaRadius)); |
| } |
| |
| static bool opposite_insets_intersect(const Geometry& geometry, |
| float strokeRadius, |
| float aaRadius) { |
| if (geometry.isEdgeAAQuad()) { |
| SkASSERT(strokeRadius == 0.f); |
| const EdgeAAQuad& quad = geometry.edgeAAQuad(); |
| if (quad.edgeFlags() == AAFlags::kNone) { |
| // If all edges are non-AA, there won't be any insetting. This allows completely non-AA |
| // quads to use the fill triangles for simpler fragment shader work. |
| return false; |
| } else if (quad.isRect() && quad.edgeFlags() == AAFlags::kAll) { |
| return opposite_insets_intersect(quad.bounds(), 0.f, aaRadius); |
| } else { |
| // Quads with mixed AA edges are tiles where non-AA edges must seam perfectly together. |
| // If we were to inset along just the axis with AA at a corner, two adjacent quads could |
| // arrive at slightly different inset coordinates and then we wouldn't have a perfect |
| // mesh. Forcing insets to snap to the center means all non-AA edges are formed solely |
| // by the original quad coordinates and should seam perfectly assuming perfect input. |
| // The only downside to this is the fill triangles cannot be used since they would |
| // partially extend into the coverage ramp from adjacent AA edges. |
| return true; |
| } |
| } else { |
| const Shape& shape = geometry.shape(); |
| if (shape.isLine()) { |
| return strokeRadius <= aaRadius; |
| } else if (shape.isRect()) { |
| return opposite_insets_intersect(shape.rect(), strokeRadius, aaRadius); |
| } else { |
| SkASSERT(shape.isRRect()); |
| return opposite_insets_intersect(shape.rrect(), strokeRadius, aaRadius); |
| } |
| } |
| } |
| |
| static bool is_clockwise(const EdgeAAQuad& quad) { |
| if (quad.isRect()) { |
| return true; // by construction, these are always locally clockwise |
| } |
| |
| // This assumes that each corner has a consistent winding, which is the case for convex inputs, |
| // which is an assumption of the per-edge AA API. Check the sign of cross product between the |
| // first two edges. |
| const skvx::float4& xs = quad.xs(); |
| const skvx::float4& ys = quad.ys(); |
| |
| float winding = (xs[0] - xs[3])*(ys[1] - ys[0]) - (ys[0] - ys[3])*(xs[1] - xs[0]); |
| if (winding == 0.f) { |
| // The input possibly forms a triangle with duplicate vertices, so check the opposite corner |
| winding = (xs[2] - xs[1])*(ys[3] - ys[2]) - (ys[2] - ys[1])*(xs[3] - xs[2]); |
| } |
| |
| // At this point if winding is < 0, the quad's vertices are CCW. If it's still 0, the vertices |
| // form a line, in which case the vertex shader constructs a correct CW winding. Otherwise, |
| // the quad or triangle vertices produce a positive winding and are CW. |
| return winding >= 0.f; |
| } |
| |
| static skvx::float2 quad_center(const EdgeAAQuad& quad) { |
| // The center of the bounding box is *not* a good center to use. Take the average of the |
| // four points instead (which is slightly biased if they form a triangle, but still okay). |
| return skvx::float2(dot(quad.xs(), skvx::float4(0.25f)), |
| dot(quad.ys(), skvx::float4(0.25f))); |
| } |
| |
| // Represents the per-vertex attributes used in each instance. |
| struct Vertex { |
| SkV2 fPosition; |
| SkV2 fNormal; |
| float fNormalScale; |
| float fCenterWeight; |
| }; |
| |
| // Allowed values for the center weight instance value (selected at record time based on style |
| // and transform), and are defined such that when (insance-weight > vertex-weight) is true, the |
| // vertex should be snapped to the center instead of its regular calculation. |
| static constexpr float kSolidInterior = 1.f; |
| static constexpr float kStrokeInterior = 0.f; |
| static constexpr float kFilledStrokeInterior = -1.f; |
| |
| // Special value for local AA radius to signal when the self-intersections of a stroke interior |
| // need extra calculations in the vertex shader. |
| static constexpr float kComplexAAInsets = -1.f; |
| |
| static constexpr int kCornerVertexCount = 9; // sk_VertexID is divided by this in SkSL |
| static constexpr int kVertexCount = 4 * kCornerVertexCount; |
| static constexpr int kIndexCount = 69; |
| |
| static void write_index_buffer(VertexWriter writer) { |
| static constexpr uint16_t kTL = 0 * kCornerVertexCount; |
| static constexpr uint16_t kTR = 1 * kCornerVertexCount; |
| static constexpr uint16_t kBR = 2 * kCornerVertexCount; |
| static constexpr uint16_t kBL = 3 * kCornerVertexCount; |
| |
| static const uint16_t kIndices[kIndexCount] = { |
| // Exterior AA ramp outset |
| kTL+0,kTL+4,kTL+1,kTL+5,kTL+2,kTL+3,kTL+5, |
| kTR+0,kTR+4,kTR+1,kTR+5,kTR+2,kTR+3,kTR+5, |
| kBR+0,kBR+4,kBR+1,kBR+5,kBR+2,kBR+3,kBR+5, |
| kBL+0,kBL+4,kBL+1,kBL+5,kBL+2,kBL+3,kBL+5, |
| kTL+0,kTL+4, // close and jump to next strip |
| // Outer to inner edges |
| kTL+4,kTL+6,kTL+5,kTL+7, |
| kTR+4,kTR+6,kTR+5,kTR+7, |
| kBR+4,kBR+6,kBR+5,kBR+7, |
| kBL+4,kBL+6,kBL+5,kBL+7, |
| kTL+4,kTL+6, // close and jump to next strip |
| // Fill triangles |
| kTL+6,kTL+8,kTL+7, kTL+7,kTR+8, |
| kTR+6,kTR+8,kTR+7, kTR+7,kBR+8, |
| kBR+6,kBR+8,kBR+7, kBR+7,kBL+8, |
| kBL+6,kBL+8,kBL+7, kBL+7,kTL+8, |
| kTL+6 // close |
| }; |
| |
| writer << kIndices; |
| } |
| |
| static void write_vertex_buffer(VertexWriter writer) { |
| // Allowed values for the normal scale attribute. +1 signals a device-space outset along the |
| // normal away from the outer edge of the stroke. 0 signals no outset, but placed on the outer |
| // edge of the stroke. -1 signals a local inset along the normal from the inner edge. |
| static constexpr float kOutset = 1.0; |
| static constexpr float kInset = -1.0; |
| |
| static constexpr float kCenter = 1.f; // "true" as a float |
| |
| // Zero, but named this way to help call out non-zero parameters. |
| static constexpr float _______ = 0.f; |
| |
| static constexpr float kHR2 = 0.5f * SK_FloatSqrt2; // "half root 2" |
| |
| // This template is repeated 4 times in the vertex buffer, for each of the four corners. |
| // The vertex ID is used to lookup per-corner instance properties such as corner radii or |
| // positions, but otherwise this vertex data produces a consistent clockwise mesh from |
| // TL -> TR -> BR -> BL. |
| static constexpr Vertex kCornerTemplate[kCornerVertexCount] = { |
| // Device-space AA outsets from outer curve |
| { {1.0f, 0.0f}, {1.0f, 0.0f}, kOutset, _______ }, |
| { {1.0f, 0.0f}, {kHR2, kHR2}, kOutset, _______ }, |
| { {0.0f, 1.0f}, {kHR2, kHR2}, kOutset, _______ }, |
| { {0.0f, 1.0f}, {0.0f, 1.0f}, kOutset, _______ }, |
| |
| // Outer anchors (no local or device-space normal outset) |
| { {1.0f, 0.0f}, {kHR2, kHR2}, _______, _______ }, |
| { {0.0f, 1.0f}, {kHR2, kHR2}, _______, _______ }, |
| |
| // Inner curve (with additional AA inset in the common case) |
| { {1.0f, 0.0f}, {1.0f, 0.0f}, kInset, _______ }, |
| { {0.0f, 1.0f}, {0.0f, 1.0f}, kInset, _______ }, |
| |
| // Center filling vertices (equal to inner AA insets unless 'center' triggers a fill). |
| // TODO: On backends that support "cull" distances (and with SkSL support), these vertices |
| // and their corresponding triangles can be completely removed. The inset vertices can |
| // set their cull distance value to cause all filling triangles to be discarded or not |
| // depending on the instance's style. |
| { {1.0f, 0.0f}, {1.0f, 0.0f}, kInset, kCenter }, |
| }; |
| |
| writer << kCornerTemplate // TL |
| << kCornerTemplate // TR |
| << kCornerTemplate // BR |
| << kCornerTemplate; // BL |
| } |
| |
| PerEdgeAAQuadRenderStep::PerEdgeAAQuadRenderStep(StaticBufferManager* bufferManager) |
| : RenderStep("PerEdgeAAQuadRenderStep", |
| "", |
| Flags::kPerformsShading | Flags::kEmitsCoverage, |
| /*uniforms=*/{}, |
| PrimitiveType::kTriangleStrip, |
| kDirectDepthGreaterPass, |
| /*vertexAttrs=*/{ |
| {"position", VertexAttribType::kFloat2, SkSLType::kFloat2}, |
| {"normal", VertexAttribType::kFloat2, SkSLType::kFloat2}, |
| // TODO: These values are all +1/0/-1, or +1/0, so could be packed |
| // much more densely than as three floats. |
| {"normalScale", VertexAttribType::kFloat, SkSLType::kFloat}, |
| {"centerWeight", VertexAttribType::kFloat, SkSLType::kFloat} |
| }, |
| /*instanceAttrs=*/ |
| {{"xRadiiOrFlags", VertexAttribType::kFloat4, SkSLType::kFloat4}, |
| {"radiiOrQuadXs", VertexAttribType::kFloat4, SkSLType::kFloat4}, |
| {"ltrbOrQuadYs", VertexAttribType::kFloat4, SkSLType::kFloat4}, |
| // XY stores center of rrect in local coords. Z and W store values to |
| // control interior fill behavior. Z can be -1, 0, or 1: |
| // -1: A stroked interior where AA insets overlap, but isn't solid. |
| // 0: A stroked interior with no complications. |
| // 1: A solid interior (fill or sufficiently large stroke width). |
| // W specifies the size of the AA inset if it's >= 0, or signals that |
| // the inner curves intersect in a complex manner (rare). |
| {"center", VertexAttribType::kFloat4, SkSLType::kFloat4}, |
| |
| // TODO: pack depth and ssboIndex into 32-bits |
| {"depth", VertexAttribType::kFloat, SkSLType::kFloat}, |
| {"ssboIndex", VertexAttribType::kInt, SkSLType::kInt}, |
| |
| {"mat0", VertexAttribType::kFloat3, SkSLType::kFloat3}, |
| {"mat1", VertexAttribType::kFloat3, SkSLType::kFloat3}, |
| {"mat2", VertexAttribType::kFloat3, SkSLType::kFloat3}}, |
| /*varyings=*/{ |
| // TODO: If the inverse transform is part of the draw's SSBO, we can |
| // reconstruct the Jacobian in the fragment shader using the existing |
| // local coordinates varying |
| {"jacobian", SkSLType::kFloat4}, // float2x2 |
| // Distance to LTRB edges of unstroked shape. Depending on |
| // 'perPixelControl' these will either be local or device-space values. |
| {"edgeDistances", SkSLType::kFloat4}, // distance to LTRB edges |
| // TODO: These are constant for all fragments for a given instance, |
| // could we store them in the draw's SSBO? |
| {"xRadii", SkSLType::kFloat4}, |
| {"yRadii", SkSLType::kFloat4}, |
| // Matches the StrokeStyle struct (X is radius, Y < 0 is round join, |
| // Y = 0 is bevel, Y > 0 is miter join). |
| // TODO: These could easily be considered part of the draw's uniforms. |
| {"strokeParams", SkSLType::kFloat2}, |
| // 'perPixelControl' is a tightly packed description of how to |
| // evaluate the possible edges that influence coverage in a pixel. |
| // The decision points and encoded values are spread across X and Y |
| // so that they are consistent regardless of whether or not MSAA is |
| // used and does not require centroid sampling. |
| // |
| // The signs of values are used to determine the type of coverage to |
| // calculate in the fragment shader and depending on the state, extra |
| // varying state is encoded in the fields: |
| // - A positive X value overrides all per-pixel coverage calculations |
| // and sets the pixel to full coverage. Y is ignored in this case. |
| // - A zero X value represents a solid interior shape. |
| // - X much less than 0 represents bidirectional coverage for a |
| // stroke, using a sufficiently negative value to avoid |
| // extrapolation from fill triangles. For actual shapes with |
| // bidirectional coverage, the fill triangles are zero area. |
| // |
| // - Y much greater than 0 takes precedence over the latter two X |
| // rules and signals that 'edgeDistances' holds device-space values |
| // and does not require additional per-pixel calculations. The |
| // coverage scale is encoded as (1+scale*w) and the bias is |
| // reconstructed from that. X is always 0 for non-fill triangles |
| // since device-space edge distance is only used for solid interiors |
| // - Otherwise, any negative Y value represents an additional |
| // reduction in coverage due to a device-space outset. It is clamped |
| // below 0 to avoid adding coverage from extrapolation. |
| {"perPixelControl", SkSLType::kFloat2}, |
| }) { |
| // Initialize the static buffers we'll use when recording draw calls. |
| // NOTE: Each instance of this RenderStep gets its own copy of the data. Since there should only |
| // ever be one PerEdgeAAQuadRenderStep at a time, this shouldn't be an issue. |
| write_vertex_buffer(bufferManager->getVertexWriter(sizeof(Vertex) * kVertexCount, |
| &fVertexBuffer)); |
| write_index_buffer(bufferManager->getIndexWriter(sizeof(uint16_t) * kIndexCount, |
| &fIndexBuffer)); |
| } |
| |
| PerEdgeAAQuadRenderStep::~PerEdgeAAQuadRenderStep() {} |
| |
| std::string PerEdgeAAQuadRenderStep::vertexSkSL() const { |
| // Returns the body of a vertex function, which must define a float4 devPosition variable and |
| // must write to an already-defined float2 stepLocalCoords variable. |
| return "float4 devPosition = per_edge_aa_quad_vertex_fn(" |
| // Vertex Attributes |
| "position, normal, normalScale, centerWeight, " |
| // Instance Attributes |
| "xRadiiOrFlags, radiiOrQuadXs, ltrbOrQuadYs, center, depth, " |
| "float3x3(mat0, mat1, mat2), " |
| // Varyings |
| "jacobian, edgeDistances, xRadii, yRadii, strokeParams, perPixelControl, " |
| // Render Step |
| "stepLocalCoords);\n"; |
| } |
| |
| const char* PerEdgeAAQuadRenderStep::fragmentCoverageSkSL() const { |
| // The returned SkSL must write its coverage into a 'half4 outputCoverage' variable (defined in |
| // the calling code) with the actual coverage splatted out into all four channels. |
| return "outputCoverage = per_edge_aa_quad_coverage_fn(sk_FragCoord, " |
| "jacobian, " |
| "edgeDistances, " |
| "xRadii, " |
| "yRadii, " |
| "strokeParams, " |
| "perPixelControl);"; |
| } |
| |
| float PerEdgeAAQuadRenderStep::boundsOutset(const Transform& localToDevice, |
| const Rect& bounds) const { |
| return local_aa_radius(localToDevice, bounds); |
| } |
| |
| void PerEdgeAAQuadRenderStep::writeVertices(DrawWriter* writer, |
| const DrawParams& params, |
| int ssboIndex) const { |
| SkASSERT(params.geometry().isShape() || params.geometry().isEdgeAAQuad()); |
| |
| DrawWriter::Instances instance{*writer, fVertexBuffer, fIndexBuffer, kIndexCount}; |
| auto vw = instance.append(1); |
| |
| // The bounds of a rect is the rect, and the bounds of a rrect is tight (== SkRRect::getRect()). |
| Rect bounds = params.geometry().bounds(); |
| |
| // aaRadius will be set to a negative value to signal a complex self-intersection that has to |
| // be calculated in the vertex shader. |
| float aaRadius = local_aa_radius(params.transform(), bounds); |
| float strokeInset = 0.f; |
| float centerWeight = kSolidInterior; |
| |
| if (params.isStroke()) { |
| // EdgeAAQuads are not stroked so we know it's a Shape, but we support rects, rrects, and |
| // lines that all need to be converted to the same form. |
| const Shape& shape = params.geometry().shape(); |
| |
| SkASSERT(params.strokeStyle().halfWidth() >= 0.f); |
| SkASSERT(shape.isRect() || shape.isLine() || params.strokeStyle().halfWidth() == 0.f || |
| (shape.isRRect() && SkRRectPriv::AllCornersCircular(shape.rrect()))); |
| |
| float strokeRadius = params.strokeStyle().halfWidth(); |
| |
| skvx::float2 size = shape.isLine() ? skvx::float2(length(shape.p1() - shape.p0()), 0.f) |
| : bounds.size(); // rect or [r]rect |
| |
| skvx::float2 innerGap = size - 2.f * params.strokeStyle().halfWidth(); |
| if (any(innerGap <= 0.f) && strokeRadius > 0.f) { |
| // AA inset intersections are measured from the *outset* and remain marked as "solid" |
| strokeInset = -strokeRadius; |
| } else { |
| // This will be upgraded to kFilledStrokeInterior if insets intersect |
| centerWeight = kStrokeInterior; |
| strokeInset = strokeRadius; |
| } |
| |
| skvx::float4 xRadii = shape.isRRect() ? load_x_radii(shape.rrect()) : skvx::float4(0.f); |
| if (strokeRadius > 0.f || shape.isLine()) { |
| // Regular strokes only need to upload 4 corner radii; hairline lines can be uploaded in |
| // the same manner since it has no real corner radii. |
| float joinStyle = params.strokeStyle().joinLimit(); |
| float lineFlag = shape.isLine() ? 1.f : 0.f; |
| auto empty = size == 0.f; |
| |
| // Points and lines produce caps instead of joins. However, the capped geometry is |
| // visually equivalent to a joined, stroked [r]rect of the paired join style. |
| if (shape.isLine() || all(empty)) { |
| // However, butt-cap points are defined not to produce any geometry, so that combo |
| // should have been rejected earlier. |
| SkASSERT(shape.isLine() || params.strokeStyle().cap() != SkPaint::kButt_Cap); |
| switch(params.strokeStyle().cap()) { |
| case SkPaint::kRound_Cap: joinStyle = -1.f; break; // round cap == round join |
| case SkPaint::kButt_Cap: joinStyle = 0.f; break; // butt cap == bevel join |
| case SkPaint::kSquare_Cap: joinStyle = 1.f; break; // square cap == miter join |
| } |
| } else if (params.strokeStyle().isMiterJoin()) { |
| // Normal corners are 90-degrees so become beveled if the miter limit is < sqrt(2). |
| // If the [r]rect has a width or height of 0, the corners are actually 180-degrees, |
| // so the must always be beveled (or, equivalently, butt-capped). |
| if (params.strokeStyle().miterLimit() < SK_ScalarSqrt2 || any(empty)) { |
| joinStyle = 0.f; // == bevel (or butt if width or height are zero) |
| } else { |
| // Discard actual miter limit because a 90-degree corner never exceeds it. |
| joinStyle = 1.f; |
| } |
| } // else no join style correction needed for non-empty geometry or round joins |
| |
| // Write a negative value outside [-1, 0] to signal a stroked shape, the line flag, then |
| // the style params, followed by corner radii and coords. |
| vw << -2.f << lineFlag << strokeRadius << joinStyle << xRadii |
| << (shape.isLine() ? shape.line() : bounds.ltrb()); |
| } else { |
| // Write -2 - cornerRadii to encode the X radii in such a way to trigger stroking but |
| // guarantee the 2nd field is non-zero to signal hairline. Then we upload Y radii as |
| // well to allow for elliptical hairlines. |
| skvx::float4 yRadii = shape.isRRect() ? load_y_radii(shape.rrect()) : skvx::float4(0.f); |
| vw << (-2.f - xRadii) << yRadii << bounds.ltrb(); |
| } |
| } else { |
| // Empty fills should not have been recorded at all. |
| SkASSERT(!bounds.isEmptyNegativeOrNaN()); |
| |
| if (params.geometry().isEdgeAAQuad()) { |
| // NOTE: If quad.isRect() && quad.edgeFlags() == kAll, the written data is identical to |
| // Shape.isRect() case below. |
| const EdgeAAQuad& quad = params.geometry().edgeAAQuad(); |
| |
| // If all edges are non-AA, set localAARadius to 0 so that the fill triangles cover the |
| // entire shape. Otherwise leave it as-is for the full AA rect case; in the event it's |
| // mixed-AA or a quad, it'll be converted to complex insets down below. |
| if (quad.edgeFlags() == EdgeAAQuad::Flags::kNone) { |
| aaRadius = 0.f; |
| } |
| |
| // -1 for AA on, 0 for AA off |
| auto edgeSigns = skvx::float4{quad.edgeFlags() & AAFlags::kLeft ? -1.f : 0.f, |
| quad.edgeFlags() & AAFlags::kTop ? -1.f : 0.f, |
| quad.edgeFlags() & AAFlags::kRight ? -1.f : 0.f, |
| quad.edgeFlags() & AAFlags::kBottom ? -1.f : 0.f}; |
| |
| // The vertex shader expects points to be in clockwise order. EdgeAAQuad is the only |
| // shape that *might* have counter-clockwise input. |
| if (is_clockwise(quad)) { |
| vw << edgeSigns << quad.xs() << quad.ys(); |
| } else { |
| vw << skvx::shuffle<2,1,0,3>(edgeSigns) // swap left and right AA bits |
| << skvx::shuffle<1,0,3,2>(quad.xs()) // swap TL with TR, and BL with BR |
| << skvx::shuffle<1,0,3,2>(quad.ys()); // "" |
| } |
| } else { |
| const Shape& shape = params.geometry().shape(); |
| // Filled lines are empty by definition, so they shouldn't have been recorded |
| SkASSERT(!shape.isLine()); |
| |
| if (shape.isRect() || (shape.isRRect() && shape.rrect().isRect())) { |
| // Rectangles (or rectangles embedded in an SkRRect) are converted to the |
| // quadrilateral case, but with all edges anti-aliased (== -1). |
| skvx::float4 ltrb = bounds.ltrb(); |
| vw << /*edge flags*/ skvx::float4(-1.f) |
| << /*xs*/ skvx::shuffle<0,2,2,0>(ltrb) |
| << /*ys*/ skvx::shuffle<1,1,3,3>(ltrb); |
| } else { |
| // A filled rounded rectangle, so make sure at least one corner radii > 0 or the |
| // shader won't detect it as a rounded rect. |
| SkASSERT(any(load_x_radii(shape.rrect()) > 0.f)); |
| |
| vw << load_x_radii(shape.rrect()) << load_y_radii(shape.rrect()) << bounds.ltrb(); |
| } |
| } |
| } |
| |
| if (opposite_insets_intersect(params.geometry(), strokeInset, aaRadius)) { |
| aaRadius = kComplexAAInsets; |
| if (centerWeight == kStrokeInterior) { |
| centerWeight = kFilledStrokeInterior; |
| } |
| } |
| |
| // All instance types share the remaining instance attribute definitions |
| const SkM44& m = params.transform().matrix(); |
| auto center = params.geometry().isEdgeAAQuad() ? quad_center(params.geometry().edgeAAQuad()) |
| : bounds.center(); |
| vw << center << centerWeight << aaRadius |
| << params.order().depthAsFloat() |
| << ssboIndex |
| << m.rc(0,0) << m.rc(1,0) << m.rc(3,0) // mat0 |
| << m.rc(0,1) << m.rc(1,1) << m.rc(3,1) // mat1 |
| << m.rc(0,3) << m.rc(1,3) << m.rc(3,3); // mat2 |
| } |
| |
| void PerEdgeAAQuadRenderStep::writeUniformsAndTextures(const DrawParams&, |
| PipelineDataGatherer*) const { |
| // All data is uploaded as instance attributes, so no uniforms are needed. |
| } |
| |
| } // namespace skgpu::graphite |
