From 38203fb4917049650c9bca2dd31e98fdac0e1d54 Mon Sep 17 00:00:00 2001
From: "reed@android.com"
 <reed@android.com@2bbb7eff-a529-9590-31e7-b0007b416f81>
Date: Fri, 26 Feb 2010 21:45:49 +0000
Subject: [PATCH] add rotation

git-svn-id: http://skia.googlecode.com/svn/trunk@513 2bbb7eff-a529-9590-31e7-b0007b416f81
---
 experimental/SkMatrix44.cpp | 56 +++++++++++++++++++++++++++++++++++--
 experimental/SkMatrix44.h   | 24 +++++++++++++++-
 2 files changed, 76 insertions(+), 4 deletions(-)

diff --git a/experimental/SkMatrix44.cpp b/experimental/SkMatrix44.cpp
index 1b1b93b988..b2b8c30465 100644
--- a/experimental/SkMatrix44.cpp
+++ b/experimental/SkMatrix44.cpp
@@ -24,15 +24,27 @@ bool SkMatrix44::isIdentity() const {
 
 void SkMatrix44::setIdentity() {
 	sk_bzero(fMat, sizeof(fMat));
-	fMat[0][0] = fMat[1][1] = fMat[2][2] = fMat[3][3] = SK_MScalar1;
+	fMat[0][0] = fMat[1][1] = fMat[2][2] = fMat[3][3] = 1;
 }
 
+void SkMatrix44::set3x3(SkMScalar m00, SkMScalar m01, SkMScalar m02,
+                        SkMScalar m10, SkMScalar m11, SkMScalar m12,
+                        SkMScalar m20, SkMScalar m21, SkMScalar m22) {
+	sk_bzero(fMat, sizeof(fMat));
+	fMat[0][0] = m00; fMat[0][1] = m01; fMat[0][2] = m02; fMat[0][3] = 0;
+	fMat[1][0] = m10; fMat[1][1] = m11; fMat[1][2] = m12; fMat[1][3] = 0;
+	fMat[2][0] = m20; fMat[2][1] = m21; fMat[2][2] = m22; fMat[2][3] = 0;
+    fMat[3][0] = 0;   fMat[3][1] = 0;   fMat[3][2] = 0;   fMat[3][3] = 1;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
 void SkMatrix44::setTranslate(SkMScalar tx, SkMScalar ty, SkMScalar tz) {
 	this->setIdentity();
 	fMat[3][0] = tx;
 	fMat[3][1] = ty;
 	fMat[3][2] = tz;
-	fMat[3][3] = SK_MScalar1;
+	fMat[3][3] = 1;
 }
 
 void SkMatrix44::preTranslate(SkMScalar dx, SkMScalar dy, SkMScalar dz) {
@@ -54,7 +66,7 @@ void SkMatrix44::setScale(SkMScalar sx, SkMScalar sy, SkMScalar sz) {
 	fMat[0][0] = sx;
     fMat[1][1] = sy;
     fMat[2][2] = sz;
-    fMat[3][3] = SK_MScalar1;
+    fMat[3][3] = 1;
 }
 
 void SkMatrix44::preScale(SkMScalar sx, SkMScalar sy, SkMScalar sz) {
@@ -73,6 +85,44 @@ void SkMatrix44::postScale(SkMScalar sx, SkMScalar sy, SkMScalar sz) {
 
 ///////////////////////////////////////////////////////////////////////////////
 
+void SkMatrix44::setRotateAbout(SkMScalar x, SkMScalar y, SkMScalar z,
+                                SkMScalar radians) {
+    double len2 = x * x + y * y + z * z;
+    if (len2 != 1) {
+        if (len2 == 0) {
+            this->setIdentity();
+            return;
+        }
+        double scale = 1 / sqrt(len2);
+        x *= scale;
+        y *= scale;
+        z *= scale;
+    }
+    this->setRotateAboutUnit(x, y, z, radians);
+}
+
+void SkMatrix44::setRotateAboutUnit(SkMScalar x, SkMScalar y, SkMScalar z,
+                                    SkMScalar radians) {
+    double c = cos(radians);
+    double s = sin(radians);
+    double C = 1 - c;
+    double xs = x * s;
+    double ys = y * s;
+    double zs = z * s;
+    double xC = x * C;
+    double yC = y * C;
+    double zC = z * C;
+    double xyC = x * yC;
+    double yzC = y * zC;
+    double zxC = z * xC;
+
+    this->set3x3(x * xC + c,    xyC - zs,       zxC + ys,
+                 xyC + zs,      y * yC + c,     yzC - xs,
+                 zxC - ys,      yzC + xs,       z * zC + c);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
 void SkMatrix44::setConcat(const SkMatrix44& a, const SkMatrix44& b) {
 	SkMScalar result[4][4];
 	for (int i = 0; i < 4; i++) {
diff --git a/experimental/SkMatrix44.h b/experimental/SkMatrix44.h
index ceba83a16f..1fe46d49cf 100644
--- a/experimental/SkMatrix44.h
+++ b/experimental/SkMatrix44.h
@@ -20,6 +20,7 @@
     static inline double SkMScalarToDouble(double x) {
         return x;
     }
+    static const SkMScalar SK_MScalarPI = 3.141592653589793;
 #else
     typedef float SkMScalar;
     static inline float SkFloatToMScalar(float x) {
@@ -34,6 +35,7 @@
     static inline double SkMScalarToDouble(float x) {
         return static_cast<double>(x);
     }
+    static const SkMScalar SK_MScalarPI = 3.14159265f;
 #endif
 
 static const SkMScalar SK_MScalar1 = 1;
@@ -68,6 +70,10 @@ public:
 	void setIdentity();
     void reset() { this->setIdentity(); }
 
+    void set3x3(SkMScalar m00, SkMScalar m01, SkMScalar m02,
+                SkMScalar m10, SkMScalar m11, SkMScalar m12,
+                SkMScalar m20, SkMScalar m21, SkMScalar m22);
+
 	void setTranslate(SkMScalar dx, SkMScalar dy, SkMScalar dz);
 	void preTranslate(SkMScalar dx, SkMScalar dy, SkMScalar dz);
 	void postTranslate(SkMScalar dx, SkMScalar dy, SkMScalar dz);
@@ -85,7 +91,23 @@ public:
     void postScale(SkMScalar scale) {
         this->postScale(scale, scale, scale);
     }
-    
+
+    void setRotateDegreesAbout(SkMScalar x, SkMScalar y, SkMScalar z,
+                        SkMScalar degrees) {
+        this->setRotateAbout(x, y, z, degrees * SK_MScalarPI / 180);
+    }
+
+    /** Rotate about the vector [x,y,z]. If that vector is not unit-length,
+        it will be automatically resized.
+     */
+    void setRotateAbout(SkMScalar x, SkMScalar y, SkMScalar z,
+                        SkMScalar radians);
+    /** Rotate about the vector [x,y,z]. Does not check the length of the
+        vector, assuming it is unit-length.
+     */
+    void setRotateAboutUnit(SkMScalar x, SkMScalar y, SkMScalar z,
+                            SkMScalar radians);
+
 	void setConcat(const SkMatrix44& a, const SkMatrix44& b);
 	void preConcat(const SkMatrix44& m) {
         this->setConcat(*this, m);
-- 
2.34.1