Add new SkPoint3 class

include/effects/SkPoint3.h

+/*
+ * 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 "SkColor.h"

[reed1, 2015/07/10 15:46:29]

why do we include this?

[robertphillips, 2015/07/10 16:54:24]

Done.

+#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();
+
+    /** Scale the point's coordinates by scale, writing the answer into dst.
+        It is legal for dst == this.
+    */
+    void scale(SkScalar scale, SkPoint3* dst) const {

[reed1, 2015/07/10 15:46:29]

as an API pattern, I think we should consider returning a new value instead for
this sort of thing.

e.g.

SkPoint3 = src.makeScale(...)

but just a thought.

[robertphillips, 2015/07/10 16:54:24]

Done. What do you think about propagating this back to SkPoint (in a separate
CL)?

+        SkASSERT(dst);
+        dst->set(SkScalarMul(fX, scale), SkScalarMul(fY, scale), SkScalarMul(fZ, scale));

[reed1, 2015/07/10 15:46:29]

SkScalarMul is not needed!

[robertphillips, 2015/07/10 16:54:24]

Done.

+    }
+
+    /** Scale the point's coordinates by scale, writing the answer back into
+        the point.
+    */
+    void scale(SkScalar value) { this->scale(value, this); }
+
+    /** 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;
+    }
+
+    /** 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;
+
+#endif