| /* |
| * 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>; |
| |
| #define AI SK_ALWAYS_INLINE |
| |
| static constexpr float kTolerance = 1e-2f; |
| |
| // These rotate the points/edge values either clockwise or counterclockwise assuming tri strip |
| // order. |
| static AI V4f next_cw(const V4f& v) { |
| return skvx::shuffle<2, 0, 3, 1>(v); |
| } |
| |
| static AI V4f next_ccw(const V4f& v) { |
| return skvx::shuffle<1, 3, 0, 2>(v); |
| } |
| |
| // Replaces zero-length 'bad' edge vectors with the reversed opposite edge vector. |
| // e3 may be null if only 2D edges need to be corrected for. |
| static AI void correct_bad_edges(const M4f& bad, V4f* e1, V4f* e2, V4f* e3) { |
| if (any(bad)) { |
| // Want opposite edges, L B T R -> R T B L but with flipped sign to preserve winding |
| *e1 = if_then_else(bad, -skvx::shuffle<3, 2, 1, 0>(*e1), *e1); |
| *e2 = if_then_else(bad, -skvx::shuffle<3, 2, 1, 0>(*e2), *e2); |
| if (e3) { |
| *e3 = if_then_else(bad, -skvx::shuffle<3, 2, 1, 0>(*e3), *e3); |
| } |
| } |
| } |
| |
| // Replace 'bad' coordinates by rotating CCW to get the next point. c3 may be null for 2D points. |
| static AI void correct_bad_coords(const M4f& bad, V4f* c1, V4f* c2, V4f* c3) { |
| if (any(bad)) { |
| *c1 = if_then_else(bad, next_ccw(*c1), *c1); |
| *c2 = if_then_else(bad, next_ccw(*c2), *c2); |
| if (c3) { |
| *c3 = if_then_else(bad, next_ccw(*c3), *c3); |
| } |
| } |
| } |
| |
| // 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. lx, ly, and lw are updated appropriately and may |
| // be null to skip calculations. Returns bit mask of edges that were clipped. |
| static GrQuadAAFlags crop_rect(const SkRect& clipDevRect, float x[4], float y[4], |
| float lx[4], float ly[4], float lw[4]) { |
| GrQuadAAFlags clipEdgeFlags = GrQuadAAFlags::kNone; |
| |
| // 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; |
| } |
| |
| return clipEdgeFlags; |
| } |
| |
| // Similar to crop_rect, but assumes that both the device coordinates and optional local coordinates |
| // geometrically match the TL, BL, TR, BR vertex ordering, i.e. axis-aligned but not flipped, etc. |
| static GrQuadAAFlags crop_simple_rect(const SkRect& clipDevRect, float x[4], float y[4], |
| float lx[4], float ly[4]) { |
| GrQuadAAFlags clipEdgeFlags = GrQuadAAFlags::kNone; |
| |
| // Update local coordinates proportionately to how much the device rect edge was clipped |
| const SkScalar dx = lx ? (lx[2] - lx[0]) / (x[2] - x[0]) : 0.f; |
| const SkScalar dy = ly ? (ly[1] - ly[0]) / (y[1] - y[0]) : 0.f; |
| if (clipDevRect.fLeft > x[0]) { |
| if (lx) { |
| lx[0] += (clipDevRect.fLeft - x[0]) * dx; |
| lx[1] = lx[0]; |
| } |
| x[0] = clipDevRect.fLeft; |
| x[1] = clipDevRect.fLeft; |
| clipEdgeFlags |= GrQuadAAFlags::kLeft; |
| } |
| if (clipDevRect.fTop > y[0]) { |
| if (ly) { |
| ly[0] += (clipDevRect.fTop - y[0]) * dy; |
| ly[2] = ly[0]; |
| } |
| y[0] = clipDevRect.fTop; |
| y[2] = clipDevRect.fTop; |
| clipEdgeFlags |= GrQuadAAFlags::kTop; |
| } |
| if (clipDevRect.fRight < x[2]) { |
| if (lx) { |
| lx[2] -= (x[2] - clipDevRect.fRight) * dx; |
| lx[3] = lx[2]; |
| } |
| x[2] = clipDevRect.fRight; |
| x[3] = clipDevRect.fRight; |
| clipEdgeFlags |= GrQuadAAFlags::kRight; |
| } |
| if (clipDevRect.fBottom < y[1]) { |
| if (ly) { |
| ly[1] -= (y[1] - clipDevRect.fBottom) * dy; |
| ly[3] = ly[1]; |
| } |
| y[1] = clipDevRect.fBottom; |
| y[3] = clipDevRect.fBottom; |
| clipEdgeFlags |= GrQuadAAFlags::kBottom; |
| } |
| |
| return clipEdgeFlags; |
| } |
| // Consistent with GrQuad::asRect()'s return value but requires fewer operations since we don't need |
| // to calculate the bounds of the quad. |
| static bool is_simple_rect(const GrQuad& quad) { |
| if (quad.quadType() != GrQuad::Type::kAxisAligned) { |
| return false; |
| } |
| // v0 at the geometric top-left is unique, so we only need to compare x[0] < x[2] for left |
| // and y[0] < y[1] for top, but add a little padding to protect against numerical precision |
| // on R90 and R270 transforms tricking this check. |
| return ((quad.x(0) + SK_ScalarNearlyZero) < quad.x(2)) && |
| ((quad.y(0) + SK_ScalarNearlyZero) < quad.y(1)); |
| } |
| |
| // 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 bool 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; |
| |
| float dot00 = v0x * v0x + v0y * v0y; |
| float dot01 = v0x * v1x + v0y * v1y; |
| float dot11 = v1x * v1x + v1y * v1y; |
| |
| // Not yet 1/d, first check d != 0 with a healthy tolerance (worst case is we end up not |
| // cropping something we could have, which is better than cropping something we shouldn't have). |
| // The tolerance is partly so large because these comparisons operate in device px^4 units, |
| // with plenty of subtractions thrown in. The SkPathOpsQuad code's use of doubles helped, and |
| // because it only needed to return "inside triangle", it could compare against [0, denom] and |
| // skip the normalization entirely. |
| float invDenom = dot00 * dot11 - dot01 * dot01; |
| static constexpr SkScalar kEmptyTriTolerance = SK_Scalar1 / (1 << 5); |
| if (SkScalarNearlyZero(invDenom, kEmptyTriTolerance)) { |
| // The triangle was degenerate/empty, which can cause the following UVW calculations to |
| // return (0,0,1) for every test point. This in turn makes the cropping code think that the |
| // empty triangle contains the crop rect and we turn the draw into a fullscreen clear, which |
| // is definitely the utter opposite of what we'd expect for an empty shape. |
| return false; |
| } else { |
| // Safe to divide |
| invDenom = sk_ieee_float_divide(1.f, invDenom); |
| } |
| |
| V4f v2x = testX - x0; |
| V4f v2y = testY - y0; |
| |
| V4f dot02 = v0x * v2x + v0y * v2y; |
| V4f dot12 = v1x * v2x + v1y * v2y; |
| |
| *u = (dot11 * dot02 - dot01 * dot12) * invDenom; |
| *v = (dot00 * dot12 - dot01 * dot02) * invDenom; |
| *w = 1.f - *u - *v; |
| |
| return true; |
| } |
| |
| 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 and crop_rect_simple keep the rectangles as rectangles, so the intersection |
| // of the crop and quad can be calculated exactly. Some care must be taken if the quad |
| // is axis-aligned but does not satisfy asRect() due to flips, etc. |
| GrQuadAAFlags clippedEdges; |
| if (local) { |
| if (is_simple_rect(*quad) && is_simple_rect(*local)) { |
| clippedEdges = crop_simple_rect(cropRect, quad->xs(), quad->ys(), |
| local->xs(), local->ys()); |
| } else { |
| clippedEdges = crop_rect(cropRect, quad->xs(), quad->ys(), |
| local->xs(), local->ys(), local->ws()); |
| } |
| } else { |
| if (is_simple_rect(*quad)) { |
| clippedEdges = crop_simple_rect(cropRect, quad->xs(), quad->ys(), nullptr, nullptr); |
| } else { |
| clippedEdges = crop_rect(cropRect, quad->xs(), quad->ys(), |
| nullptr, nullptr, nullptr); |
| } |
| } |
| |
| // Apply the clipped edge updates to the original edge flags |
| if (cropAA == GrAA::kYes) { |
| // Turn on all edges that were clipped |
| *edgeFlags |= clippedEdges; |
| } else { |
| // Turn off all edges that were clipped |
| *edgeFlags &= ~clippedEdges; |
| } |
| 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; |
| V4f u2, v2, w2; |
| if (!barycentric_coords(devX[0], devY[0], devX[1], devY[1], devX[2], devY[2], clipX, clipY, |
| &u1, &v1, &w1) || |
| !barycentric_coords(devX[1], devY[1], devX[3], devY[3], devX[2], devY[2], clipX, clipY, |
| &u2, &v2, &w2)) { |
| // Bad triangles, skip cropping |
| return false; |
| } |
| |
| // 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; |
| } |
| |
| /////////////////////////////////////////////////////////////////////////////////////////////////// |
| // TessellationHelper implementation and helper struct implementations |
| /////////////////////////////////////////////////////////////////////////////////////////////////// |
| |
| //** EdgeVectors implementation |
| |
| void TessellationHelper::EdgeVectors::reset(const skvx::Vec<4, float>& xs, |
| const skvx::Vec<4, float>& ys, |
| const skvx::Vec<4, float>& ws, |
| GrQuad::Type quadType) { |
| // Calculate all projected edge vector values for this quad. |
| if (quadType == GrQuad::Type::kPerspective) { |
| V4f iw = 1.0 / ws; |
| fX2D = xs * iw; |
| fY2D = ys * iw; |
| } else { |
| fX2D = xs; |
| fY2D = ys; |
| } |
| |
| fDX = next_ccw(fX2D) - fX2D; |
| fDY = next_ccw(fY2D) - fY2D; |
| fInvLengths = rsqrt(mad(fDX, fDX, fDY * fDY)); |
| |
| // Normalize edge vectors |
| fDX *= fInvLengths; |
| fDY *= fInvLengths; |
| |
| // Calculate angles between vectors |
| if (quadType <= GrQuad::Type::kRectilinear) { |
| fCosTheta = 0.f; |
| fInvSinTheta = 1.f; |
| } else { |
| fCosTheta = mad(fDX, next_cw(fDX), fDY * next_cw(fDY)); |
| // NOTE: if cosTheta is close to 1, inset/outset math will avoid the fast paths that rely |
| // on thefInvSinTheta since it will approach infinity. |
| fInvSinTheta = rsqrt(1.f - fCosTheta * fCosTheta); |
| } |
| } |
| |
| //** EdgeEquations implementation |
| |
| void TessellationHelper::EdgeEquations::reset(const EdgeVectors& edgeVectors) { |
| V4f dx = edgeVectors.fDX; |
| V4f dy = edgeVectors.fDY; |
| // Correct for bad edges by copying adjacent edge information into the bad component |
| correct_bad_edges(edgeVectors.fInvLengths >= 1.f / kTolerance, &dx, &dy, nullptr); |
| |
| V4f c = mad(dx, edgeVectors.fY2D, -dy * edgeVectors.fX2D); |
| // Make sure normals point into the shape |
| V4f test = mad(dy, next_cw(edgeVectors.fX2D), mad(-dx, next_cw(edgeVectors.fY2D), c)); |
| if (any(test < -kTolerance)) { |
| fA = -dy; |
| fB = dx; |
| fC = -c; |
| } else { |
| fA = dy; |
| fB = -dx; |
| fC = c; |
| } |
| } |
| |
| V4f TessellationHelper::EdgeEquations::estimateCoverage(const V4f& x2d, const V4f& y2d) const { |
| // Calculate distance of the 4 inset points (px, py) to the 4 edges |
| V4f d0 = mad(fA[0], x2d, mad(fB[0], y2d, fC[0])); |
| V4f d1 = mad(fA[1], x2d, mad(fB[1], y2d, fC[1])); |
| V4f d2 = mad(fA[2], x2d, mad(fB[2], y2d, fC[2])); |
| V4f d3 = mad(fA[3], x2d, mad(fB[3], y2d, fC[3])); |
| |
| // For each point, pretend that there's a rectangle that touches e0 and e3 on the horizontal |
| // axis, so its width is "approximately" d0 + d3, and it touches e1 and e2 on the vertical axis |
| // so its height is d1 + d2. Pin each of these dimensions to [0, 1] and approximate the coverage |
| // at each point as clamp(d0+d3, 0, 1) x clamp(d1+d2, 0, 1). For rectilinear quads this is an |
| // accurate calculation of its area clipped to an aligned pixel. For arbitrary quads it is not |
| // mathematically accurate but qualitatively provides a stable value proportional to the size of |
| // the shape. |
| V4f w = max(0.f, min(1.f, d0 + d3)); |
| V4f h = max(0.f, min(1.f, d1 + d2)); |
| return w * h; |
| } |
| |
| int TessellationHelper::EdgeEquations::computeDegenerateQuad(const V4f& signedEdgeDistances, |
| V4f* x2d, V4f* y2d) const { |
| // Move the edge by the signed edge adjustment. |
| V4f oc = fC + signedEdgeDistances; |
| |
| // There are 6 points that we care about to determine the final shape of the polygon, which |
| // are the intersections between (e0,e2), (e1,e0), (e2,e3), (e3,e1) (corresponding to the |
| // 4 corners), and (e1, e2), (e0, e3) (representing the intersections of opposite edges). |
| V4f denom = fA * next_cw(fB) - fB * next_cw(fA); |
| V4f px = (fB * next_cw(oc) - oc * next_cw(fB)) / denom; |
| V4f py = (oc * next_cw(fA) - fA * next_cw(oc)) / denom; |
| correct_bad_coords(abs(denom) < kTolerance, &px, &py, nullptr); |
| |
| // Calculate the signed distances from these 4 corners to the other two edges that did not |
| // define the intersection. So p(0) is compared to e3,e1, p(1) to e3,e2 , p(2) to e0,e1, and |
| // p(3) to e0,e2 |
| V4f dists1 = px * skvx::shuffle<3, 3, 0, 0>(fA) + |
| py * skvx::shuffle<3, 3, 0, 0>(fB) + |
| skvx::shuffle<3, 3, 0, 0>(oc); |
| V4f dists2 = px * skvx::shuffle<1, 2, 1, 2>(fA) + |
| py * skvx::shuffle<1, 2, 1, 2>(fB) + |
| skvx::shuffle<1, 2, 1, 2>(oc); |
| |
| // If all the distances are >= 0, the 4 corners form a valid quadrilateral, so use them as |
| // the 4 points. If any point is on the wrong side of both edges, the interior has collapsed |
| // and we need to use a central point to represent it. If all four points are only on the |
| // wrong side of 1 edge, one edge has crossed over another and we use a line to represent it. |
| // Otherwise, use a triangle that replaces the bad points with the intersections of |
| // (e1, e2) or (e0, e3) as needed. |
| M4f d1v0 = dists1 < kTolerance; |
| M4f d2v0 = dists2 < kTolerance; |
| M4f d1And2 = d1v0 & d2v0; |
| M4f d1Or2 = d1v0 | d2v0; |
| |
| if (!any(d1Or2)) { |
| // Every dists1 and dists2 >= kTolerance so it's not degenerate, use all 4 corners as-is |
| // and use full coverage |
| *x2d = px; |
| *y2d = py; |
| return 4; |
| } else if (any(d1And2)) { |
| // A point failed against two edges, so reduce the shape to a single point, which we take as |
| // the center of the original quad to ensure it is contained in the intended geometry. Since |
| // it has collapsed, we know the shape cannot cover a pixel so update the coverage. |
| SkPoint center = {0.25f * ((*x2d)[0] + (*x2d)[1] + (*x2d)[2] + (*x2d)[3]), |
| 0.25f * ((*y2d)[0] + (*y2d)[1] + (*y2d)[2] + (*y2d)[3])}; |
| *x2d = center.fX; |
| *y2d = center.fY; |
| return 1; |
| } else if (all(d1Or2)) { |
| // Degenerates to a line. Compare p[2] and p[3] to edge 0. If they are on the wrong side, |
| // that means edge 0 and 3 crossed, and otherwise edge 1 and 2 crossed. |
| if (dists1[2] < kTolerance && dists1[3] < kTolerance) { |
| // Edges 0 and 3 have crossed over, so make the line from average of (p0,p2) and (p1,p3) |
| *x2d = 0.5f * (skvx::shuffle<0, 1, 0, 1>(px) + skvx::shuffle<2, 3, 2, 3>(px)); |
| *y2d = 0.5f * (skvx::shuffle<0, 1, 0, 1>(py) + skvx::shuffle<2, 3, 2, 3>(py)); |
| } else { |
| // Edges 1 and 2 have crossed over, so make the line from average of (p0,p1) and (p2,p3) |
| *x2d = 0.5f * (skvx::shuffle<0, 0, 2, 2>(px) + skvx::shuffle<1, 1, 3, 3>(px)); |
| *y2d = 0.5f * (skvx::shuffle<0, 0, 2, 2>(py) + skvx::shuffle<1, 1, 3, 3>(py)); |
| } |
| return 2; |
| } else { |
| // This turns into a triangle. Replace corners as needed with the intersections between |
| // (e0,e3) and (e1,e2), which must now be calculated |
| using V2f = skvx::Vec<2, float>; |
| V2f eDenom = skvx::shuffle<0, 1>(fA) * skvx::shuffle<3, 2>(fB) - |
| skvx::shuffle<0, 1>(fB) * skvx::shuffle<3, 2>(fA); |
| V2f ex = (skvx::shuffle<0, 1>(fB) * skvx::shuffle<3, 2>(oc) - |
| skvx::shuffle<0, 1>(oc) * skvx::shuffle<3, 2>(fB)) / eDenom; |
| V2f ey = (skvx::shuffle<0, 1>(oc) * skvx::shuffle<3, 2>(fA) - |
| skvx::shuffle<0, 1>(fA) * skvx::shuffle<3, 2>(oc)) / eDenom; |
| |
| if (SkScalarAbs(eDenom[0]) > kTolerance) { |
| px = if_then_else(d1v0, V4f(ex[0]), px); |
| py = if_then_else(d1v0, V4f(ey[0]), py); |
| } |
| if (SkScalarAbs(eDenom[1]) > kTolerance) { |
| px = if_then_else(d2v0, V4f(ex[1]), px); |
| py = if_then_else(d2v0, V4f(ey[1]), py); |
| } |
| |
| *x2d = px; |
| *y2d = py; |
| return 3; |
| } |
| } |
| |
| //** OutsetRequest implementation |
| |
| void TessellationHelper::OutsetRequest::reset(const EdgeVectors& edgeVectors, GrQuad::Type quadType, |
| const skvx::Vec<4, float>& edgeDistances) { |
| fEdgeDistances = edgeDistances; |
| |
| // Based on the edge distances, determine if it's acceptable to use fInvSinTheta to |
| // calculate the inset or outset geometry. |
| if (quadType <= GrQuad::Type::kRectilinear) { |
| // Since it's rectangular, the width (edge[1] or edge[2]) collapses if subtracting |
| // (dist[0] + dist[3]) makes the new width negative (minus for inset, outsetting will |
| // never be degenerate in this case). The same applies for height (edge[0] or edge[3]) |
| // and (dist[1] + dist[2]). |
| fOutsetDegenerate = false; |
| float widthChange = edgeDistances[0] + edgeDistances[3]; |
| float heightChange = edgeDistances[1] + edgeDistances[2]; |
| // (1/len > 1/(edge sum) implies len - edge sum < 0. |
| fInsetDegenerate = |
| (widthChange > 0.f && edgeVectors.fInvLengths[1] > 1.f / widthChange) || |
| (heightChange > 0.f && edgeVectors.fInvLengths[0] > 1.f / heightChange); |
| } else if (any(edgeVectors.fInvLengths >= 1.f / kTolerance)) { |
| // Have an edge that is effectively length 0, so we're dealing with a triangle, which |
| // must always go through the degenerate code path. |
| fOutsetDegenerate = true; |
| fInsetDegenerate = true; |
| } else { |
| // If possible, the corners will move +/-edgeDistances * 1/sin(theta). The entire |
| // request is degenerate if 1/sin(theta) -> infinity (or cos(theta) -> 1). |
| if (any(abs(edgeVectors.fCosTheta) >= 0.9f)) { |
| fOutsetDegenerate = true; |
| fInsetDegenerate = true; |
| } else { |
| // With an edge-centric view, an edge's length changes by |
| // edgeDistance * cos(pi - theta) / sin(theta) for each of its corners (the second |
| // corner uses ccw theta value). An edge's length also changes when its adjacent |
| // edges move, in which case it's updated by edgeDistance / sin(theta) |
| // (or cos(theta) for the other edge). |
| |
| // cos(pi - theta) = -cos(theta) |
| V4f halfTanTheta = -edgeVectors.fCosTheta * edgeVectors.fInvSinTheta; |
| V4f edgeAdjust = edgeDistances * (halfTanTheta + next_ccw(halfTanTheta)) + |
| next_ccw(edgeDistances) * next_ccw(edgeVectors.fInvSinTheta) + |
| next_cw(edgeDistances) * edgeVectors.fInvSinTheta; |
| |
| // If either outsetting (plus edgeAdjust) or insetting (minus edgeAdjust) make |
| // the edge lengths negative, then it's degenerate. |
| V4f threshold = 0.1f - (1.f / edgeVectors.fInvLengths); |
| fOutsetDegenerate = any(edgeAdjust < threshold); |
| fInsetDegenerate = any(edgeAdjust > -threshold); |
| } |
| } |
| } |
| |
| //** Vertices implementation |
| |
| void TessellationHelper::Vertices::reset(const GrQuad& deviceQuad, const GrQuad* localQuad) { |
| // Set vertices to match the device and local quad |
| fX = deviceQuad.x4f(); |
| fY = deviceQuad.y4f(); |
| fW = deviceQuad.w4f(); |
| |
| if (localQuad) { |
| fU = localQuad->x4f(); |
| fV = localQuad->y4f(); |
| fR = localQuad->w4f(); |
| fUVRCount = localQuad->hasPerspective() ? 3 : 2; |
| } else { |
| fUVRCount = 0; |
| } |
| } |
| |
| void TessellationHelper::Vertices::asGrQuads(GrQuad* deviceOut, GrQuad::Type deviceType, |
| GrQuad* localOut, GrQuad::Type localType) const { |
| SkASSERT(deviceOut); |
| SkASSERT(fUVRCount == 0 || localOut); |
| |
| fX.store(deviceOut->xs()); |
| fY.store(deviceOut->ys()); |
| if (deviceType == GrQuad::Type::kPerspective) { |
| fW.store(deviceOut->ws()); |
| } |
| deviceOut->setQuadType(deviceType); // This sets ws == 1 when device type != perspective |
| |
| if (fUVRCount > 0) { |
| fU.store(localOut->xs()); |
| fV.store(localOut->ys()); |
| if (fUVRCount == 3) { |
| fR.store(localOut->ws()); |
| } |
| localOut->setQuadType(localType); |
| } |
| } |
| |
| void TessellationHelper::Vertices::moveAlong(const EdgeVectors& edgeVectors, |
| const V4f& signedEdgeDistances) { |
| // This shouldn't be called if fInvSinTheta is close to infinity (cosTheta close to 1). |
| SkASSERT(all(abs(edgeVectors.fCosTheta) < 0.9f)); |
| |
| // When the projected device quad is not degenerate, the vertex corners can move |
| // cornerOutsetLen along their edge and their cw-rotated edge. The vertex's edge points |
| // inwards and the cw-rotated edge points outwards, hence the minus-sign. |
| // The edge distances are rotated compared to the corner outsets and (dx, dy), since if |
| // the edge is "on" both its corners need to be moved along their other edge vectors. |
| V4f signedOutsets = -edgeVectors.fInvSinTheta * next_cw(signedEdgeDistances); |
| V4f signedOutsetsCW = edgeVectors.fInvSinTheta * signedEdgeDistances; |
| |
| // x = x + outset * mask * next_cw(xdiff) - outset * next_cw(mask) * xdiff |
| fX += mad(signedOutsetsCW, next_cw(edgeVectors.fDX), signedOutsets * edgeVectors.fDX); |
| fY += mad(signedOutsetsCW, next_cw(edgeVectors.fDY), signedOutsets * edgeVectors.fDY); |
| if (fUVRCount > 0) { |
| // We want to extend the texture coords by the same proportion as the positions. |
| signedOutsets *= edgeVectors.fInvLengths; |
| signedOutsetsCW *= next_cw(edgeVectors.fInvLengths); |
| V4f du = next_ccw(fU) - fU; |
| V4f dv = next_ccw(fV) - fV; |
| fU += mad(signedOutsetsCW, next_cw(du), signedOutsets * du); |
| fV += mad(signedOutsetsCW, next_cw(dv), signedOutsets * dv); |
| if (fUVRCount == 3) { |
| V4f dr = next_ccw(fR) - fR; |
| fR += mad(signedOutsetsCW, next_cw(dr), signedOutsets * dr); |
| } |
| } |
| } |
| |
| void TessellationHelper::Vertices::moveTo(const V4f& x2d, const V4f& y2d, const M4f& mask) { |
| // Left to right, in device space, for each point |
| V4f e1x = skvx::shuffle<2, 3, 2, 3>(fX) - skvx::shuffle<0, 1, 0, 1>(fX); |
| V4f e1y = skvx::shuffle<2, 3, 2, 3>(fY) - skvx::shuffle<0, 1, 0, 1>(fY); |
| V4f e1w = skvx::shuffle<2, 3, 2, 3>(fW) - skvx::shuffle<0, 1, 0, 1>(fW); |
| correct_bad_edges(mad(e1x, e1x, e1y * e1y) < kTolerance * kTolerance, &e1x, &e1y, &e1w); |
| |
| // // Top to bottom, in device space, for each point |
| V4f e2x = skvx::shuffle<1, 1, 3, 3>(fX) - skvx::shuffle<0, 0, 2, 2>(fX); |
| V4f e2y = skvx::shuffle<1, 1, 3, 3>(fY) - skvx::shuffle<0, 0, 2, 2>(fY); |
| V4f e2w = skvx::shuffle<1, 1, 3, 3>(fW) - skvx::shuffle<0, 0, 2, 2>(fW); |
| correct_bad_edges(mad(e2x, e2x, e2y * e2y) < kTolerance * kTolerance, &e2x, &e2y, &e2w); |
| |
| // Can only move along e1 and e2 to reach the new 2D point, so we have |
| // x2d = (x + a*e1x + b*e2x) / (w + a*e1w + b*e2w) and |
| // y2d = (y + a*e1y + b*e2y) / (w + a*e1w + b*e2w) for some a, b |
| // This can be rewritten to a*c1x + b*c2x + c3x = 0; a * c1y + b*c2y + c3y = 0, where |
| // the cNx and cNy coefficients are: |
| V4f c1x = e1w * x2d - e1x; |
| V4f c1y = e1w * y2d - e1y; |
| V4f c2x = e2w * x2d - e2x; |
| V4f c2y = e2w * y2d - e2y; |
| V4f c3x = fW * x2d - fX; |
| V4f c3y = fW * y2d - fY; |
| |
| // Solve for a and b |
| V4f a, b, denom; |
| if (all(mask)) { |
| // When every edge is outset/inset, each corner can use both edge vectors |
| denom = c1x * c2y - c2x * c1y; |
| a = (c2x * c3y - c3x * c2y) / denom; |
| b = (c3x * c1y - c1x * c3y) / denom; |
| } else { |
| // Force a or b to be 0 if that edge cannot be used due to non-AA |
| M4f aMask = skvx::shuffle<0, 0, 3, 3>(mask); |
| M4f bMask = skvx::shuffle<2, 1, 2, 1>(mask); |
| |
| // When aMask[i]&bMask[i], then a[i], b[i], denom[i] match the kAll case. |
| // When aMask[i]&!bMask[i], then b[i] = 0, a[i] = -c3x/c1x or -c3y/c1y, using better denom |
| // When !aMask[i]&bMask[i], then a[i] = 0, b[i] = -c3x/c2x or -c3y/c2y, "" |
| // When !aMask[i]&!bMask[i], then both a[i] = 0 and b[i] = 0 |
| M4f useC1x = abs(c1x) > abs(c1y); |
| M4f useC2x = abs(c2x) > abs(c2y); |
| |
| denom = if_then_else(aMask, |
| if_then_else(bMask, |
| c1x * c2y - c2x * c1y, /* A & B */ |
| if_then_else(useC1x, c1x, c1y)), /* A & !B */ |
| if_then_else(bMask, |
| if_then_else(useC2x, c2x, c2y), /* !A & B */ |
| V4f(1.f))); /* !A & !B */ |
| |
| a = if_then_else(aMask, |
| if_then_else(bMask, |
| c2x * c3y - c3x * c2y, /* A & B */ |
| if_then_else(useC1x, -c3x, -c3y)), /* A & !B */ |
| V4f(0.f)) / denom; /* !A */ |
| b = if_then_else(bMask, |
| if_then_else(aMask, |
| c3x * c1y - c1x * c3y, /* A & B */ |
| if_then_else(useC2x, -c3x, -c3y)), /* !A & B */ |
| V4f(0.f)) / denom; /* !B */ |
| } |
| |
| V4f newW = fW + a * e1w + b * e2w; |
| // If newW < 0, scale a and b such that the point reaches the infinity plane instead of crossing |
| // This breaks orthogonality of inset/outsets, but GPUs don't handle negative Ws well so this |
| // is far less visually disturbing (likely not noticeable since it's at extreme perspective). |
| // The alternative correction (multiply xyw by -1) has the disadvantage of changing how local |
| // coordinates would be interpolated. |
| static const float kMinW = 1e-6f; |
| if (any(newW < 0.f)) { |
| V4f scale = if_then_else(newW < kMinW, (kMinW - fW) / (newW - fW), V4f(1.f)); |
| a *= scale; |
| b *= scale; |
| } |
| |
| fX += a * e1x + b * e2x; |
| fY += a * e1y + b * e2y; |
| fW += a * e1w + b * e2w; |
| correct_bad_coords(abs(denom) < kTolerance, &fX, &fY, &fW); |
| |
| if (fUVRCount > 0) { |
| // Calculate R here so it can be corrected with U and V in case it's needed later |
| V4f e1u = skvx::shuffle<2, 3, 2, 3>(fU) - skvx::shuffle<0, 1, 0, 1>(fU); |
| V4f e1v = skvx::shuffle<2, 3, 2, 3>(fV) - skvx::shuffle<0, 1, 0, 1>(fV); |
| V4f e1r = skvx::shuffle<2, 3, 2, 3>(fR) - skvx::shuffle<0, 1, 0, 1>(fR); |
| correct_bad_edges(mad(e1u, e1u, e1v * e1v) < kTolerance * kTolerance, &e1u, &e1v, &e1r); |
| |
| V4f e2u = skvx::shuffle<1, 1, 3, 3>(fU) - skvx::shuffle<0, 0, 2, 2>(fU); |
| V4f e2v = skvx::shuffle<1, 1, 3, 3>(fV) - skvx::shuffle<0, 0, 2, 2>(fV); |
| V4f e2r = skvx::shuffle<1, 1, 3, 3>(fR) - skvx::shuffle<0, 0, 2, 2>(fR); |
| correct_bad_edges(mad(e2u, e2u, e2v * e2v) < kTolerance * kTolerance, &e2u, &e2v, &e2r); |
| |
| fU += a * e1u + b * e2u; |
| fV += a * e1v + b * e2v; |
| if (fUVRCount == 3) { |
| fR += a * e1r + b * e2r; |
| correct_bad_coords(abs(denom) < kTolerance, &fU, &fV, &fR); |
| } else { |
| correct_bad_coords(abs(denom) < kTolerance, &fU, &fV, nullptr); |
| } |
| } |
| } |
| |
| //** TessellationHelper implementation |
| |
| void TessellationHelper::reset(const GrQuad& deviceQuad, const GrQuad* localQuad) { |
| // Record basic state that isn't recorded on the Vertices struct itself |
| fDeviceType = deviceQuad.quadType(); |
| fLocalType = localQuad ? localQuad->quadType() : GrQuad::Type::kAxisAligned; |
| |
| // Reset metadata validity |
| fOutsetRequestValid = false; |
| fEdgeEquationsValid = false; |
| |
| // Compute vertex properties that are always needed for a quad, so no point in doing it lazily. |
| fOriginal.reset(deviceQuad, localQuad); |
| fEdgeVectors.reset(fOriginal.fX, fOriginal.fY, fOriginal.fW, fDeviceType); |
| |
| fVerticesValid = true; |
| } |
| |
| V4f TessellationHelper::inset(const skvx::Vec<4, float>& edgeDistances, |
| GrQuad* deviceInset, GrQuad* localInset) { |
| SkASSERT(fVerticesValid); |
| |
| Vertices inset = fOriginal; |
| const OutsetRequest& request = this->getOutsetRequest(edgeDistances); |
| int vertexCount; |
| if (request.fInsetDegenerate) { |
| vertexCount = this->adjustDegenerateVertices(-request.fEdgeDistances, &inset); |
| } else { |
| this->adjustVertices(-request.fEdgeDistances, &inset); |
| vertexCount = 4; |
| } |
| |
| inset.asGrQuads(deviceInset, fDeviceType, localInset, fLocalType); |
| if (vertexCount < 3) { |
| // The interior has less than a full pixel's area so estimate reduced coverage using |
| // the distance of the inset's projected corners to the original edges. |
| return this->getEdgeEquations().estimateCoverage(inset.fX / inset.fW, |
| inset.fY / inset.fW); |
| } else { |
| return 1.f; |
| } |
| } |
| |
| void TessellationHelper::outset(const skvx::Vec<4, float>& edgeDistances, |
| GrQuad* deviceOutset, GrQuad* localOutset) { |
| SkASSERT(fVerticesValid); |
| |
| Vertices outset = fOriginal; |
| const OutsetRequest& request = this->getOutsetRequest(edgeDistances); |
| if (request.fOutsetDegenerate) { |
| this->adjustDegenerateVertices(request.fEdgeDistances, &outset); |
| } else { |
| this->adjustVertices(request.fEdgeDistances, &outset); |
| } |
| |
| outset.asGrQuads(deviceOutset, fDeviceType, localOutset, fLocalType); |
| } |
| |
| const TessellationHelper::OutsetRequest& TessellationHelper::getOutsetRequest( |
| const skvx::Vec<4, float>& edgeDistances) { |
| // Much of the code assumes that we start from positive distances and apply it unmodified to |
| // create an outset; knowing that it's outset simplifies degeneracy checking. |
| SkASSERT(all(edgeDistances >= 0.f)); |
| |
| // Rebuild outset request if invalid or if the edge distances have changed. |
| if (!fOutsetRequestValid || any(edgeDistances != fOutsetRequest.fEdgeDistances)) { |
| fOutsetRequest.reset(fEdgeVectors, fDeviceType, edgeDistances); |
| fOutsetRequestValid = true; |
| } |
| return fOutsetRequest; |
| } |
| |
| const TessellationHelper::EdgeEquations& TessellationHelper::getEdgeEquations() { |
| if (!fEdgeEquationsValid) { |
| fEdgeEquations.reset(fEdgeVectors); |
| fEdgeEquationsValid = true; |
| } |
| return fEdgeEquations; |
| } |
| |
| void TessellationHelper::adjustVertices(const skvx::Vec<4, float>& signedEdgeDistances, |
| Vertices* vertices) { |
| SkASSERT(vertices); |
| SkASSERT(vertices->fUVRCount == 0 || vertices->fUVRCount == 2 || vertices->fUVRCount == 3); |
| |
| if (fDeviceType < GrQuad::Type::kPerspective) { |
| // For non-perspective, non-degenerate quads, moveAlong is correct and most efficient |
| vertices->moveAlong(fEdgeVectors, signedEdgeDistances); |
| } else { |
| // For perspective, non-degenerate quads, use moveAlong for the projected points and then |
| // reconstruct Ws with moveTo. |
| Vertices projected = { fEdgeVectors.fX2D, fEdgeVectors.fY2D, /*w*/ 1.f, 0.f, 0.f, 0.f, 0 }; |
| projected.moveAlong(fEdgeVectors, signedEdgeDistances); |
| vertices->moveTo(projected.fX, projected.fY, signedEdgeDistances != 0.f); |
| } |
| } |
| |
| int TessellationHelper::adjustDegenerateVertices(const skvx::Vec<4, float>& signedEdgeDistances, |
| Vertices* vertices) { |
| SkASSERT(vertices); |
| SkASSERT(vertices->fUVRCount == 0 || vertices->fUVRCount == 2 || vertices->fUVRCount == 3); |
| |
| if (fDeviceType <= GrQuad::Type::kRectilinear) { |
| // For rectilinear, degenerate quads, can use moveAlong if the edge distances are adjusted |
| // to not cross over each other. |
| SkASSERT(all(signedEdgeDistances <= 0.f)); // Only way rectilinear can degenerate is insets |
| V4f halfLengths = -0.5f / next_cw(fEdgeVectors.fInvLengths); // Negate to inset |
| M4f crossedEdges = halfLengths > signedEdgeDistances; |
| V4f safeInsets = if_then_else(crossedEdges, halfLengths, signedEdgeDistances); |
| vertices->moveAlong(fEdgeVectors, safeInsets); |
| |
| // A degenerate rectilinear quad is either a point (both w and h crossed), or a line |
| return all(crossedEdges) ? 1 : 2; |
| } else { |
| // Degenerate non-rectangular shape, must go through slowest path (which automatically |
| // handles perspective). |
| V4f x2d = fEdgeVectors.fX2D; |
| V4f y2d = fEdgeVectors.fY2D; |
| int vertexCount = this->getEdgeEquations().computeDegenerateQuad(signedEdgeDistances, |
| &x2d, &y2d); |
| vertices->moveTo(x2d, y2d, signedEdgeDistances != 0.f); |
| return vertexCount; |
| } |
| } |
| |
| }; // namespace GrQuadUtils |
