Update SkLightingShader to support rotation

This also:
makes the SkLightingShader handle normal maps where the rects aren't aligned between the diffuse and normal maps.

adds a light aggregating class (Lights) to SkLightingShader (along with a Builder nested class).

Split out of https://codereview.chromium.org/1261433009/ (Add SkCanvas::drawLitAtlas call)

Committed: https://skia.googlesource.com/skia/+/45b59ed6e4e231814dbdb9f707b3d2a7ee50de84

Review URL: https://codereview.chromium.org/1291783003

1 files changed, 124 insertions, 0 deletions

diff --git a/include/core/SkPoint3.h b/include/core/SkPoint3.h
new file mode 100644
index 0000000000..af24a8df58
--- /dev/null
+++ b/include/core/SkPoint3.h
@@ -0,0 +1,124 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkPoint3_DEFINED
+#define SkPoint3_DEFINED
+
+#include "SkScalar.h"
+
+struct SK_API SkPoint3 {
+    SkScalar fX, fY, fZ;
+
+    static SkPoint3 Make(SkScalar x, SkScalar y, SkScalar z) {
+        SkPoint3 pt;
+        pt.set(x, y, z);
+        return pt;
+    }
+
+    SkScalar x() const { return fX; }
+    SkScalar y() const { return fY; }
+    SkScalar z() const { return fZ; }
+
+    void set(SkScalar x, SkScalar y, SkScalar z) { fX = x; fY = y; fZ = z; }
+
+    friend bool operator==(const SkPoint3& a, const SkPoint3& b) {
+        return a.fX == b.fX && a.fY == b.fY && a.fZ == b.fZ;
+    }
+
+    friend bool operator!=(const SkPoint3& a, const SkPoint3& b) {
+        return !(a == b);
+    }
+
+    /** Returns the Euclidian distance from (0,0,0) to (x,y,z)
+    */
+    static SkScalar Length(SkScalar x, SkScalar y, SkScalar z);
+
+    /** Return the Euclidian distance from (0,0,0) to the point
+    */
+    SkScalar length() const { return SkPoint3::Length(fX, fY, fZ); }
+
+    /** Set the point (vector) to be unit-length in the same direction as it
+        already points.  If the point has a degenerate length (i.e., nearly 0)
+        then set it to (0,0,0) and return false; otherwise return true.
+    */
+    bool normalize();
+
+    /** Return a new point whose X, Y and Z coordinates are scaled.
+    */
+    SkPoint3 makeScale(SkScalar scale) const {
+        SkPoint3 p;
+        p.set(scale * fX, scale * fY, scale * fZ);
+        return p;
+    }
+
+    /** Scale the point's coordinates by scale.
+    */
+    void scale(SkScalar value) { 
+        fX *= value;
+        fY *= value;
+        fZ *= value;
+    }
+
+    /** Return a new point whose X, Y and Z coordinates are the negative of the
+        original point's
+    */
+    SkPoint3 operator-() const {
+        SkPoint3 neg;
+        neg.fX = -fX;
+        neg.fY = -fY;
+        neg.fZ = -fZ;
+        return neg;
+    }
+
+    /** Returns a new point whose coordinates are the difference between
+        a and b (i.e., a - b)
+    */
+    friend SkPoint3 operator-(const SkPoint3& a, const SkPoint3& b) {
+        SkPoint3 v;
+        v.set(a.fX - b.fX, a.fY - b.fY, a.fZ - b.fZ);
+        return v;
+    }
+
+    /** Returns a new point whose coordinates are the sum of a and b (a + b)
+    */
+    friend SkPoint3 operator+(const SkPoint3& a, const SkPoint3& b) {
+        SkPoint3 v;
+        v.set(a.fX + b.fX, a.fY + b.fY, a.fZ + b.fZ);
+        return v;
+    }
+
+    /** Add v's coordinates to the point's
+    */
+    void operator+=(const SkPoint3& v) {
+        fX += v.fX;
+        fY += v.fY;
+        fZ += v.fZ;
+    }
+
+    /** Subtract v's coordinates from the point's
+    */
+    void operator-=(const SkPoint3& v) {
+        fX -= v.fX;
+        fY -= v.fY;
+        fZ -= v.fZ;
+    }
+
+    /** Returns the dot product of a and b, treating them as 3D vectors
+    */
+    static SkScalar DotProduct(const SkPoint3& a, const SkPoint3& b) {
+        return a.fX * b.fX + a.fY * b.fY + a.fZ * b.fZ;
+    }
+
+    SkScalar dot(const SkPoint3& vec) const {
+        return DotProduct(*this, vec);
+    }
+};
+
+typedef SkPoint3 SkVector3;
+typedef SkPoint3 SkColor3f;
+
+#endif