commit 63f0354b6d8a1b5c77d700f9ca797d35532b8a17
author Jim Van Verth <jvanverth@google.com> Wed Dec 16 11:56:11 2020 -0500
committer Skia Commit-Bot <skia-commit-bot@chromium.org> Wed Dec 16 16:58:26 2020 +0000
tree 7c3fc83b09ce6511b6c10d9be5be606d3914c42c
parent 67d2d73d063ca416993e8ed5b4101150bf4b1ca7

Add support for directional lights.

Adds a new kDirectionLight_ShadowFlag which indicates that lightPosition
is a vector pointing towards the light, and lightRadius is the blur
radius when the occluder is at z == 1. For other values of z it will
scale linearly. The direction is specified in device space.

Bug: skia:10781
Change-Id: I14d530f006e5541ed6e22bfbeb29c7441c21fb8e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/321792
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>

src/utils/SkShadowTessellator.cpp

diff --git a/src/utils/SkShadowTessellator.cpp b/src/utils/SkShadowTessellator.cpp
index 450b4ff..9baa29c 100644
--- a/src/utils/SkShadowTessellator.cpp
+++ b/src/utils/SkShadowTessellator.cpp
@@ -991,7 +991,7 @@
 public:
     SkSpotShadowTessellator(const SkPath& path, const SkMatrix& ctm,
                             const SkPoint3& zPlaneParams, const SkPoint3& lightPos,
-                            SkScalar lightRadius, bool transparent);
+                            SkScalar lightRadius, bool transparent, bool directional);
 
 private:
     bool computeClipAndPathPolygons(const SkPath& path, const SkMatrix& ctm,
@@ -1004,14 +1004,14 @@
 SkSpotShadowTessellator::SkSpotShadowTessellator(const SkPath& path, const SkMatrix& ctm,
                                                  const SkPoint3& zPlaneParams,
                                                  const SkPoint3& lightPos, SkScalar lightRadius,
-                                                 bool transparent)
+                                                 bool transparent, bool directional)
     : INHERITED(zPlaneParams, path.getBounds(), transparent) {
 
     // Compute the blur radius, scale and translation for the spot shadow.
     SkMatrix shadowTransform;
     SkScalar outset;
-    if (!SkDrawShadowMetrics::GetSpotShadowTransform(lightPos, lightRadius,
-                                                     ctm, zPlaneParams, path.getBounds(),
+    if (!SkDrawShadowMetrics::GetSpotShadowTransform(lightPos, lightRadius, ctm, zPlaneParams,
+                                                     path.getBounds(), directional,
                                                      &shadowTransform, &outset)) {
         return;
     }
@@ -1159,12 +1159,14 @@
 
 sk_sp<SkVertices> SkShadowTessellator::MakeSpot(const SkPath& path, const SkMatrix& ctm,
                                                 const SkPoint3& zPlane, const SkPoint3& lightPos,
-                                                SkScalar lightRadius,  bool transparent) {
+                                                SkScalar lightRadius,  bool transparent,
+                                                bool directional) {
     if (!ctm.mapRect(path.getBounds()).isFinite() || !zPlane.isFinite() ||
         !lightPos.isFinite() || !(lightPos.fZ >= SK_ScalarNearlyZero) ||
         !SkScalarIsFinite(lightRadius) || !(lightRadius >= SK_ScalarNearlyZero)) {
         return nullptr;
     }
-    SkSpotShadowTessellator spotTess(path, ctm, zPlane, lightPos, lightRadius, transparent);
+    SkSpotShadowTessellator spotTess(path, ctm, zPlane, lightPos, lightRadius, transparent,
+                                     directional);
     return spotTess.releaseVertices();
 }