| /* |
| * Copyright 2019 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/geometry/GrQuadUtils.h" |
| |
| #include "include/core/SkRect.h" |
| #include "include/private/GrTypesPriv.h" |
| #include "include/private/SkVx.h" |
| #include "src/gpu/geometry/GrQuad.h" |
| |
| using V4f = skvx::Vec<4, float>; |
| using M4f = skvx::Vec<4, int32_t>; |
| |
| // Since the local quad may not be type kRect, this uses the opposites for each vertex when |
| // interpolating, and calculates new ws in addition to new xs, ys. |
| static void interpolate_local(float alpha, int v0, int v1, int v2, int v3, |
| float lx[4], float ly[4], float lw[4]) { |
| SkASSERT(v0 >= 0 && v0 < 4); |
| SkASSERT(v1 >= 0 && v1 < 4); |
| SkASSERT(v2 >= 0 && v2 < 4); |
| SkASSERT(v3 >= 0 && v3 < 4); |
| |
| float beta = 1.f - alpha; |
| lx[v0] = alpha * lx[v0] + beta * lx[v2]; |
| ly[v0] = alpha * ly[v0] + beta * ly[v2]; |
| lw[v0] = alpha * lw[v0] + beta * lw[v2]; |
| |
| lx[v1] = alpha * lx[v1] + beta * lx[v3]; |
| ly[v1] = alpha * ly[v1] + beta * ly[v3]; |
| lw[v1] = alpha * lw[v1] + beta * lw[v3]; |
| } |
| |
| // Crops v0 to v1 based on the clipDevRect. v2 is opposite of v0, v3 is opposite of v1. |
| // It is written to not modify coordinates if there's no intersection along the edge. |
| // Ideally this would have been detected earlier and the entire draw is skipped. |
| static bool crop_rect_edge(const SkRect& clipDevRect, int v0, int v1, int v2, int v3, |
| float x[4], float y[4], float lx[4], float ly[4], float lw[4]) { |
| SkASSERT(v0 >= 0 && v0 < 4); |
| SkASSERT(v1 >= 0 && v1 < 4); |
| SkASSERT(v2 >= 0 && v2 < 4); |
| SkASSERT(v3 >= 0 && v3 < 4); |
| |
| if (SkScalarNearlyEqual(x[v0], x[v1])) { |
| // A vertical edge |
| if (x[v0] < clipDevRect.fLeft && x[v2] >= clipDevRect.fLeft) { |
| // Overlapping with left edge of clipDevRect |
| if (lx) { |
| float alpha = (x[v2] - clipDevRect.fLeft) / (x[v2] - x[v0]); |
| interpolate_local(alpha, v0, v1, v2, v3, lx, ly, lw); |
| } |
| x[v0] = clipDevRect.fLeft; |
| x[v1] = clipDevRect.fLeft; |
| return true; |
| } else if (x[v0] > clipDevRect.fRight && x[v2] <= clipDevRect.fRight) { |
| // Overlapping with right edge of clipDevRect |
| if (lx) { |
| float alpha = (clipDevRect.fRight - x[v2]) / (x[v0] - x[v2]); |
| interpolate_local(alpha, v0, v1, v2, v3, lx, ly, lw); |
| } |
| x[v0] = clipDevRect.fRight; |
| x[v1] = clipDevRect.fRight; |
| return true; |
| } |
| } else { |
| // A horizontal edge |
| SkASSERT(SkScalarNearlyEqual(y[v0], y[v1])); |
| if (y[v0] < clipDevRect.fTop && y[v2] >= clipDevRect.fTop) { |
| // Overlapping with top edge of clipDevRect |
| if (lx) { |
| float alpha = (y[v2] - clipDevRect.fTop) / (y[v2] - y[v0]); |
| interpolate_local(alpha, v0, v1, v2, v3, lx, ly, lw); |
| } |
| y[v0] = clipDevRect.fTop; |
| y[v1] = clipDevRect.fTop; |
| return true; |
| } else if (y[v0] > clipDevRect.fBottom && y[v2] <= clipDevRect.fBottom) { |
| // Overlapping with bottom edge of clipDevRect |
| if (lx) { |
| float alpha = (clipDevRect.fBottom - y[v2]) / (y[v0] - y[v2]); |
| interpolate_local(alpha, v0, v1, v2, v3, lx, ly, lw); |
| } |
| y[v0] = clipDevRect.fBottom; |
| y[v1] = clipDevRect.fBottom; |
| return true; |
| } |
| } |
| |
| // No overlap so don't crop it |
| return false; |
| } |
| |
| // Updates x and y to intersect with clipDevRect, and applies clipAA policy to edgeFlags for each |
| // intersected edge. lx, ly, and lw are updated appropriately and may be null to skip calculations. |
| static void crop_rect(const SkRect& clipDevRect, GrAA clipAA, GrQuadAAFlags* edgeFlags, |
| float x[4], float y[4], float lx[4], float ly[4], float lw[4]) { |
| // Filled in as if clipAA were true, will be inverted at the end if needed. |
| GrQuadAAFlags clipEdgeFlags = GrQuadAAFlags::kNone; |
| |
| // However, the quad's left edge may not align with the SkRect notion of left due to 90 degree |
| // rotations or mirrors. So, this processes the logical edges of the quad and clamps it to the 4 |
| // sides of clipDevRect. |
| |
| // Quad's left is v0 to v1 (op. v2 and v3) |
| if (crop_rect_edge(clipDevRect, 0, 1, 2, 3, x, y, lx, ly, lw)) { |
| clipEdgeFlags |= GrQuadAAFlags::kLeft; |
| } |
| // Quad's top edge is v0 to v2 (op. v1 and v3) |
| if (crop_rect_edge(clipDevRect, 0, 2, 1, 3, x, y, lx, ly, lw)) { |
| clipEdgeFlags |= GrQuadAAFlags::kTop; |
| } |
| // Quad's right edge is v2 to v3 (op. v0 and v1) |
| if (crop_rect_edge(clipDevRect, 2, 3, 0, 1, x, y, lx, ly, lw)) { |
| clipEdgeFlags |= GrQuadAAFlags::kRight; |
| } |
| // Quad's bottom edge is v1 to v3 (op. v0 and v2) |
| if (crop_rect_edge(clipDevRect, 1, 3, 0, 2, x, y, lx, ly, lw)) { |
| clipEdgeFlags |= GrQuadAAFlags::kBottom; |
| } |
| |
| if (clipAA == GrAA::kYes) { |
| // Turn on all edges that were clipped |
| *edgeFlags |= clipEdgeFlags; |
| } else { |
| // Turn off all edges that were clipped |
| *edgeFlags &= ~clipEdgeFlags; |
| } |
| } |
| |
| // Calculates barycentric coordinates for each point in (testX, testY) in the triangle formed by |
| // (x0,y0) - (x1,y1) - (x2, y2) and stores them in u, v, w. |
| static void barycentric_coords(float x0, float y0, float x1, float y1, float x2, float y2, |
| const V4f& testX, const V4f& testY, |
| V4f* u, V4f* v, V4f* w) { |
| // Modeled after SkPathOpsQuad::pointInTriangle() but uses float instead of double, is |
| // vectorized and outputs normalized barycentric coordinates instead of inside/outside test |
| float v0x = x2 - x0; |
| float v0y = y2 - y0; |
| float v1x = x1 - x0; |
| float v1y = y1 - y0; |
| V4f v2x = testX - x0; |
| V4f v2y = testY - y0; |
| |
| float dot00 = v0x * v0x + v0y * v0y; |
| float dot01 = v0x * v1x + v0y * v1y; |
| V4f dot02 = v0x * v2x + v0y * v2y; |
| float dot11 = v1x * v1x + v1y * v1y; |
| V4f dot12 = v1x * v2x + v1y * v2y; |
| float invDenom = sk_ieee_float_divide(1.f, dot00 * dot11 - dot01 * dot01); |
| *u = (dot11 * dot02 - dot01 * dot12) * invDenom; |
| *v = (dot00 * dot12 - dot01 * dot02) * invDenom; |
| *w = 1.f - *u - *v; |
| } |
| |
| static M4f inside_triangle(const V4f& u, const V4f& v, const V4f& w) { |
| return ((u >= 0.f) & (u <= 1.f)) & ((v >= 0.f) & (v <= 1.f)) & ((w >= 0.f) & (w <= 1.f)); |
| } |
| |
| namespace GrQuadUtils { |
| |
| void ResolveAAType(GrAAType requestedAAType, GrQuadAAFlags requestedEdgeFlags, const GrQuad& quad, |
| GrAAType* outAAType, GrQuadAAFlags* outEdgeFlags) { |
| // Most cases will keep the requested types unchanged |
| *outAAType = requestedAAType; |
| *outEdgeFlags = requestedEdgeFlags; |
| |
| switch (requestedAAType) { |
| // When aa type is coverage, disable AA if the edge configuration doesn't actually need it |
| case GrAAType::kCoverage: |
| if (requestedEdgeFlags == GrQuadAAFlags::kNone) { |
| // Turn off anti-aliasing |
| *outAAType = GrAAType::kNone; |
| } else { |
| // For coverage AA, if the quad is a rect and it lines up with pixel boundaries |
| // then overall aa and per-edge aa can be completely disabled |
| if (quad.quadType() == GrQuad::Type::kAxisAligned && !quad.aaHasEffectOnRect()) { |
| *outAAType = GrAAType::kNone; |
| *outEdgeFlags = GrQuadAAFlags::kNone; |
| } |
| } |
| break; |
| // For no or msaa anti aliasing, override the edge flags since edge flags only make sense |
| // when coverage aa is being used. |
| case GrAAType::kNone: |
| *outEdgeFlags = GrQuadAAFlags::kNone; |
| break; |
| case GrAAType::kMSAA: |
| *outEdgeFlags = GrQuadAAFlags::kAll; |
| break; |
| } |
| } |
| |
| bool CropToRect(const SkRect& cropRect, GrAA cropAA, GrQuadAAFlags* edgeFlags, GrQuad* quad, |
| GrQuad* local) { |
| SkASSERT(quad->isFinite()); |
| |
| if (quad->quadType() == GrQuad::Type::kAxisAligned) { |
| // crop_rect keeps the rectangles as rectangles, so there's no need to modify types |
| if (local) { |
| crop_rect(cropRect, cropAA, edgeFlags, quad->xs(), quad->ys(), |
| local->xs(), local->ys(), local->ws()); |
| } else { |
| crop_rect(cropRect, cropAA, edgeFlags, quad->xs(), quad->ys(), |
| nullptr, nullptr, nullptr); |
| } |
| return true; |
| } |
| |
| if (local) { |
| // FIXME (michaelludwig) Calculate cropped local coordinates when not kAxisAligned |
| return false; |
| } |
| |
| V4f devX = quad->x4f(); |
| V4f devY = quad->y4f(); |
| V4f devIW = quad->iw4f(); |
| // Project the 3D coordinates to 2D |
| if (quad->quadType() == GrQuad::Type::kPerspective) { |
| devX *= devIW; |
| devY *= devIW; |
| } |
| |
| V4f clipX = {cropRect.fLeft, cropRect.fLeft, cropRect.fRight, cropRect.fRight}; |
| V4f clipY = {cropRect.fTop, cropRect.fBottom, cropRect.fTop, cropRect.fBottom}; |
| |
| // Calculate barycentric coordinates for the 4 rect corners in the 2 triangles that the quad |
| // is tessellated into when drawn. |
| V4f u1, v1, w1; |
| barycentric_coords(devX[0], devY[0], devX[1], devY[1], devX[2], devY[2], clipX, clipY, |
| &u1, &v1, &w1); |
| V4f u2, v2, w2; |
| barycentric_coords(devX[1], devY[1], devX[3], devY[3], devX[2], devY[2], clipX, clipY, |
| &u2, &v2, &w2); |
| |
| // clipDevRect is completely inside this quad if each corner is in at least one of two triangles |
| M4f inTri1 = inside_triangle(u1, v1, w1); |
| M4f inTri2 = inside_triangle(u2, v2, w2); |
| if (all(inTri1 | inTri2)) { |
| // We can crop to exactly the clipDevRect. |
| // FIXME (michaelludwig) - there are other ways to have determined quad covering the clip |
| // rect, but the barycentric coords will be useful to derive local coordinates in the future |
| |
| // Since we are cropped to exactly clipDevRect, we have discarded any perspective and the |
| // type becomes kRect. If updated locals were requested, they will incorporate perspective. |
| // FIXME (michaelludwig) - once we have local coordinates handled, it may be desirable to |
| // keep the draw as perspective so that the hardware does perspective interpolation instead |
| // of pushing it into a local coord w and having the shader do an extra divide. |
| clipX.store(quad->xs()); |
| clipY.store(quad->ys()); |
| quad->ws()[0] = 1.f; |
| quad->ws()[1] = 1.f; |
| quad->ws()[2] = 1.f; |
| quad->ws()[3] = 1.f; |
| quad->setQuadType(GrQuad::Type::kAxisAligned); |
| |
| // Update the edge flags to match the clip setting since all 4 edges have been clipped |
| *edgeFlags = cropAA == GrAA::kYes ? GrQuadAAFlags::kAll : GrQuadAAFlags::kNone; |
| |
| return true; |
| } |
| |
| // FIXME (michaelludwig) - use the GrQuadPerEdgeAA tessellation inset/outset math to move |
| // edges to the closest clip corner they are outside of |
| |
| return false; |
| } |
| |
| }; // namespace GrQuadUtils |
