| /* |
| * Copyright 2017 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #include "include/core/SkMatrix.h" |
| #include "include/core/SkPath.h" |
| #include "include/core/SkRect.h" |
| #include "src/core/SkDrawShadowInfo.h" |
| #include "src/utils/SkPolyUtils.h" |
| |
| namespace SkDrawShadowMetrics { |
| |
| static SkScalar compute_z(SkScalar x, SkScalar y, const SkPoint3& params) { |
| return x*params.fX + y*params.fY + params.fZ; |
| } |
| |
| bool GetSpotShadowTransform(const SkPoint3& lightPos, SkScalar lightRadius, |
| const SkMatrix& ctm, const SkPoint3& zPlaneParams, |
| const SkRect& pathBounds, SkMatrix* shadowTransform, SkScalar* radius) { |
| auto heightFunc = [zPlaneParams] (SkScalar x, SkScalar y) { |
| return zPlaneParams.fX*x + zPlaneParams.fY*y + zPlaneParams.fZ; |
| }; |
| SkScalar occluderHeight = heightFunc(pathBounds.centerX(), pathBounds.centerY()); |
| |
| if (!ctm.hasPerspective()) { |
| SkScalar scale; |
| SkVector translate; |
| SkDrawShadowMetrics::GetSpotParams(occluderHeight, lightPos.fX, lightPos.fY, lightPos.fZ, |
| lightRadius, radius, &scale, &translate); |
| shadowTransform->setScaleTranslate(scale, scale, translate.fX, translate.fY); |
| shadowTransform->preConcat(ctm); |
| } else { |
| if (SkScalarNearlyZero(pathBounds.width()) || SkScalarNearlyZero(pathBounds.height())) { |
| return false; |
| } |
| |
| // get rotated quad in 3D |
| SkPoint pts[4]; |
| ctm.mapRectToQuad(pts, pathBounds); |
| // No shadows for bowties or other degenerate cases |
| if (!SkIsConvexPolygon(pts, 4)) { |
| return false; |
| } |
| SkPoint3 pts3D[4]; |
| SkScalar z = heightFunc(pathBounds.fLeft, pathBounds.fTop); |
| pts3D[0].set(pts[0].fX, pts[0].fY, z); |
| z = heightFunc(pathBounds.fRight, pathBounds.fTop); |
| pts3D[1].set(pts[1].fX, pts[1].fY, z); |
| z = heightFunc(pathBounds.fRight, pathBounds.fBottom); |
| pts3D[2].set(pts[2].fX, pts[2].fY, z); |
| z = heightFunc(pathBounds.fLeft, pathBounds.fBottom); |
| pts3D[3].set(pts[3].fX, pts[3].fY, z); |
| |
| // project from light through corners to z=0 plane |
| for (int i = 0; i < 4; ++i) { |
| SkScalar dz = lightPos.fZ - pts3D[i].fZ; |
| // light shouldn't be below or at a corner's z-location |
| if (dz <= SK_ScalarNearlyZero) { |
| return false; |
| } |
| SkScalar zRatio = pts3D[i].fZ / dz; |
| pts3D[i].fX -= (lightPos.fX - pts3D[i].fX)*zRatio; |
| pts3D[i].fY -= (lightPos.fY - pts3D[i].fY)*zRatio; |
| pts3D[i].fZ = SK_Scalar1; |
| } |
| |
| // Generate matrix that projects from [-1,1]x[-1,1] square to projected quad |
| SkPoint3 h0, h1, h2; |
| // Compute homogenous crossing point between top and bottom edges (gives new x-axis). |
| h0 = (pts3D[1].cross(pts3D[0])).cross(pts3D[2].cross(pts3D[3])); |
| // Compute homogenous crossing point between left and right edges (gives new y-axis). |
| h1 = (pts3D[0].cross(pts3D[3])).cross(pts3D[1].cross(pts3D[2])); |
| // Compute homogenous crossing point between diagonals (gives new origin). |
| h2 = (pts3D[0].cross(pts3D[2])).cross(pts3D[1].cross(pts3D[3])); |
| // If h2 is a vector (z=0 in 2D homogeneous space), that means that at least |
| // two of the quad corners are coincident and we don't have a realistic projection |
| if (SkScalarNearlyZero(h2.fZ)) { |
| return false; |
| } |
| // In some cases the crossing points are in the wrong direction |
| // to map (-1,-1) to pts3D[0], so we need to correct for that. |
| // Want h0 to be to the right of the left edge. |
| SkVector3 v = pts3D[3] - pts3D[0]; |
| SkVector3 w = h0 - pts3D[0]; |
| SkScalar perpDot = v.fX*w.fY - v.fY*w.fX; |
| if (perpDot > 0) { |
| h0 = -h0; |
| } |
| // Want h1 to be above the bottom edge. |
| v = pts3D[1] - pts3D[0]; |
| perpDot = v.fX*w.fY - v.fY*w.fX; |
| if (perpDot < 0) { |
| h1 = -h1; |
| } |
| shadowTransform->setAll(h0.fX / h2.fZ, h1.fX / h2.fZ, h2.fX / h2.fZ, |
| h0.fY / h2.fZ, h1.fY / h2.fZ, h2.fY / h2.fZ, |
| h0.fZ / h2.fZ, h1.fZ / h2.fZ, 1); |
| // generate matrix that transforms from bounds to [-1,1]x[-1,1] square |
| SkMatrix toHomogeneous; |
| SkScalar xScale = 2/(pathBounds.fRight - pathBounds.fLeft); |
| SkScalar yScale = 2/(pathBounds.fBottom - pathBounds.fTop); |
| toHomogeneous.setAll(xScale, 0, -xScale*pathBounds.fLeft - 1, |
| 0, yScale, -yScale*pathBounds.fTop - 1, |
| 0, 0, 1); |
| shadowTransform->preConcat(toHomogeneous); |
| |
| *radius = SkDrawShadowMetrics::SpotBlurRadius(occluderHeight, lightPos.fZ, lightRadius); |
| } |
| |
| return true; |
| } |
| |
| void GetLocalBounds(const SkPath& path, const SkDrawShadowRec& rec, const SkMatrix& ctm, |
| SkRect* bounds) { |
| SkRect ambientBounds = path.getBounds(); |
| SkScalar occluderZ; |
| if (SkScalarNearlyZero(rec.fZPlaneParams.fX) && SkScalarNearlyZero(rec.fZPlaneParams.fY)) { |
| occluderZ = rec.fZPlaneParams.fZ; |
| } else { |
| occluderZ = compute_z(ambientBounds.fLeft, ambientBounds.fTop, rec.fZPlaneParams); |
| occluderZ = std::max(occluderZ, compute_z(ambientBounds.fRight, ambientBounds.fTop, |
| rec.fZPlaneParams)); |
| occluderZ = std::max(occluderZ, compute_z(ambientBounds.fLeft, ambientBounds.fBottom, |
| rec.fZPlaneParams)); |
| occluderZ = std::max(occluderZ, compute_z(ambientBounds.fRight, ambientBounds.fBottom, |
| rec.fZPlaneParams)); |
| } |
| SkScalar ambientBlur; |
| SkScalar spotBlur; |
| SkScalar spotScale; |
| SkPoint spotOffset; |
| if (ctm.hasPerspective()) { |
| // transform ambient and spot bounds into device space |
| ctm.mapRect(&ambientBounds); |
| |
| // get ambient blur (in device space) |
| ambientBlur = SkDrawShadowMetrics::AmbientBlurRadius(occluderZ); |
| |
| // get spot params (in device space) |
| SkPoint devLightPos = SkPoint::Make(rec.fLightPos.fX, rec.fLightPos.fY); |
| ctm.mapPoints(&devLightPos, 1); |
| SkDrawShadowMetrics::GetSpotParams(occluderZ, devLightPos.fX, devLightPos.fY, |
| rec.fLightPos.fZ, rec.fLightRadius, |
| &spotBlur, &spotScale, &spotOffset); |
| } else { |
| SkScalar devToSrcScale = SkScalarInvert(ctm.getMinScale()); |
| |
| // get ambient blur (in local space) |
| SkScalar devSpaceAmbientBlur = SkDrawShadowMetrics::AmbientBlurRadius(occluderZ); |
| ambientBlur = devSpaceAmbientBlur*devToSrcScale; |
| |
| // get spot params (in local space) |
| SkDrawShadowMetrics::GetSpotParams(occluderZ, rec.fLightPos.fX, rec.fLightPos.fY, |
| rec.fLightPos.fZ, rec.fLightRadius, |
| &spotBlur, &spotScale, &spotOffset); |
| |
| // convert spot blur to local space |
| spotBlur *= devToSrcScale; |
| } |
| |
| // in both cases, adjust ambient and spot bounds |
| SkRect spotBounds = ambientBounds; |
| ambientBounds.outset(ambientBlur, ambientBlur); |
| spotBounds.fLeft *= spotScale; |
| spotBounds.fTop *= spotScale; |
| spotBounds.fRight *= spotScale; |
| spotBounds.fBottom *= spotScale; |
| spotBounds.offset(spotOffset.fX, spotOffset.fY); |
| spotBounds.outset(spotBlur, spotBlur); |
| |
| // merge bounds |
| *bounds = ambientBounds; |
| bounds->join(spotBounds); |
| // outset a bit to account for floating point error |
| bounds->outset(1, 1); |
| |
| // if perspective, transform back to src space |
| if (ctm.hasPerspective()) { |
| // TODO: create tighter mapping from dev rect back to src rect |
| SkMatrix inverse; |
| if (ctm.invert(&inverse)) { |
| inverse.mapRect(bounds); |
| } |
| } |
| } |
| |
| |
| } |
| |
