Add perspective support to blur shadows
Bug: skia:7971
Change-Id: Iaf6049bc9b8286c7ee314cfa5a0b8e3287b95bfd
Reviewed-on: https://skia-review.googlesource.com/154632
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
diff --git a/src/utils/SkShadowTessellator.cpp b/src/utils/SkShadowTessellator.cpp
index 9deebea..943ff05 100644
--- a/src/utils/SkShadowTessellator.cpp
+++ b/src/utils/SkShadowTessellator.cpp
@@ -986,93 +986,13 @@
bool transparent)
: INHERITED(zPlaneParams, transparent) {
- const SkRect& pathBounds = path.getBounds();
-
- // Set radius and colors
- SkScalar occluderHeight = this->heightFunc(pathBounds.centerX(), pathBounds.centerY());
-
// Compute the blur radius, scale and translation for the spot shadow.
- SkScalar outset;
SkMatrix shadowTransform;
- if (!ctm.hasPerspective()) {
- SkScalar scale;
- SkVector translate;
- SkDrawShadowMetrics::GetSpotParams(occluderHeight, lightPos.fX, lightPos.fY, lightPos.fZ,
- lightRadius, &outset, &scale, &translate);
- shadowTransform.setScaleTranslate(scale, scale, translate.fX, translate.fY);
- shadowTransform.preConcat(ctm);
- } else {
- // 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;
- }
- SkPoint3 pts3D[4];
- SkScalar z = this->heightFunc(pathBounds.fLeft, pathBounds.fTop);
- pts3D[0].set(pts[0].fX, pts[0].fY, z);
- z = this->heightFunc(pathBounds.fRight, pathBounds.fTop);
- pts3D[1].set(pts[1].fX, pts[1].fY, z);
- z = this->heightFunc(pathBounds.fRight, pathBounds.fBottom);
- pts3D[2].set(pts[2].fX, pts[2].fY, z);
- z = this->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;
- }
- 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;
- }
- // 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);
-
- outset = SkDrawShadowMetrics::SpotBlurRadius(occluderHeight, lightPos.fZ, lightRadius);
+ SkScalar outset;
+ if (!SkDrawShadowMetrics::GetSpotShadowTransform(lightPos, lightRadius,
+ ctm, zPlaneParams, path.getBounds(),
+ &shadowTransform, &outset)) {
+ return;
}
SkScalar inset = outset;