Update SkLightingShader to take a localMatrix

gm/lightingshader.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "gm.h"
 
 #include "SkColorPriv.h"
 #include "SkLightingShader.h"
 
 static SkBitmap make_checkerboard(int texSize) {
     SkBitmap bitmap;
     bitmap.allocN32Pixels(texSize, texSize);
 
     SkCanvas canvas(bitmap);
     sk_tool_utils::draw_checkerboard(&canvas,
                                      sk_tool_utils::color_to_565(0x0),
                                      sk_tool_utils::color_to_565(0xFF804020),
-                                     16);
+                                     2);
     return bitmap;
 }
 
 // Create a hemispherical normal map
-static SkBitmap make_normalmap(int texSize) {
+static SkBitmap make_hemi_normalmap(int texSize) {
     SkBitmap hemi;
     hemi.allocN32Pixels(texSize, texSize);
 
     for (int y = 0; y < texSize; ++y) {
         for (int x = 0; x < texSize; ++x) {
             SkScalar locX = (x + 0.5f - texSize/2.0f) / (texSize/2.0f);
             SkScalar locY = (y + 0.5f - texSize/2.0f) / (texSize/2.0f);
             
             SkScalar locZ = locX * locX + locY * locY;
             if (locZ >= 1.0f) {
                 locX = 0.0f;
                 locY = 0.0f;
                 locZ = 0.0f;
             }
             locZ = sqrt(1.0f - locZ);
             unsigned char r = static_cast<unsigned char>((0.5f * locX + 0.5f) * 255);
             unsigned char g = static_cast<unsigned char>((-0.5f * locY + 0.5f) * 255);
             unsigned char b = static_cast<unsigned char>((0.5f * locZ + 0.5f) * 255);
             *hemi.getAddr32(x, y) = SkPackARGB32(0xFF, r, g, b);
         }
     }
 
     return hemi;
 }
 
+// Create a truncated pyramid normal map
+static SkBitmap make_frustum_normalmap(int texSize) {
+    SkBitmap frustum;
+    frustum.allocN32Pixels(texSize, texSize);
+
+    SkIRect inner = SkIRect::MakeWH(texSize, texSize);
+    inner.inset(texSize/4, texSize/4);
+
+    SkPoint3 norm;
+    const SkPoint3 left =  SkPoint3::Make(-SK_ScalarRoot2Over2, 0.0f, SK_ScalarRoot2Over2);
+    const SkPoint3 up =    SkPoint3::Make(0.0f, -SK_ScalarRoot2Over2, SK_ScalarRoot2Over2);
+    const SkPoint3 right = SkPoint3::Make(SK_ScalarRoot2Over2,  0.0f, SK_ScalarRoot2Over2);
+    const SkPoint3 down =  SkPoint3::Make(0.0f,  SK_ScalarRoot2Over2, SK_ScalarRoot2Over2);
+
+    for (int y = 0; y < texSize; ++y) {
+        for (int x = 0; x < texSize; ++x) {
+            if (inner.contains(x, y)) {
+                norm.set(0.0f, 0.0f, 1.0f);
+            } else {
+                SkScalar locX = x + 0.5f - texSize/2.0f;
+                SkScalar locY = y + 0.5f - texSize/2.0f;
+
+                if (locX >= 0.0f) {
+                    if (locY > 0.0f) {
+                        norm = locX >= locY ? right : down;   // LR corner
+                    } else {
+                        norm = locX > -locY ? right : up;     // UR corner
+                    }    
+                } else {
+                    if (locY > 0.0f) {
+                        norm = -locX > locY ? left : down;    // LL corner
+                    } else {
+                        norm = locX > locY ? up : left;       // UL corner
+                    }    
+                }
+            }
+
+            SkASSERT(SkScalarNearlyEqual(norm.length(), 1.0f));
+            unsigned char r = static_cast<unsigned char>((0.5f *  norm.fX + 0.5f) * 255);
+            unsigned char g = static_cast<unsigned char>((-0.5f * norm.fY + 0.5f) * 255);
+            unsigned char b = static_cast<unsigned char>((0.5f *  norm.fZ + 0.5f) * 255);
+            *frustum.getAddr32(x, y) = SkPackARGB32(0xFF, r, g, b);
+        }
+    }
+
+    return frustum;
+}
 
 namespace skiagm {
 
 // This GM exercises lighting shaders.
 class LightingShaderGM : public GM {
 public:
     LightingShaderGM() {
         this->setBGColor(sk_tool_utils::color_to_565(0xFFCCCCCC));
+
+        fLight.fColor = SkColorSetRGB(0xff, 0xff, 0xff);
+        fLight.fDirection.fX = 0.0f;
+        fLight.fDirection.fY = 0.0f;
+        fLight.fDirection.fZ = 1.0f;
+
+        fAmbient = SkColorSetRGB(0x1f, 0x1f, 0x1f);
     }
 
 protected:
 
     SkString onShortName() override {
         return SkString("lightingshader");
     }
 
     SkISize onISize() override {
-        return SkISize::Make(kTexSize, kTexSize);
+        return SkISize::Make(kGMSize, kGMSize);
     }
 
     void onOnceBeforeDraw() override {
         fDiffuse = make_checkerboard(kTexSize);
-        fNormalMap = make_normalmap(kTexSize);
+        fHemiNormalMap = make_hemi_normalmap(kTexSize);
+        fFrustumNormalMap = make_frustum_normalmap(kTexSize);
     }
 
-    void onDraw(SkCanvas* canvas) override {
+    void drawRect(SkCanvas* canvas, const SkRect& r, bool hemi) {
 
-        SkColor ambient = SkColorSetRGB(0x1f, 0x1f, 0x1f);
+        SkRect bitmapBounds = SkRect::MakeIWH(fDiffuse.width(), fDiffuse.height());
 
-        SkLightingShader::Light light;
-        light.fColor = SkColorSetRGB(0xff, 0xff, 0xff);
-        light.fDirection.fX = 0.0f;
-        light.fDirection.fY = 0.0f;
-        light.fDirection.fZ = 1.0f;
-
-        SkAutoTUnref<SkShader> fShader(SkLightingShader::Create(fDiffuse, fNormalMap, 
-                                                                light, ambient));
+        SkMatrix matrix;
+        matrix.setRectToRect(bitmapBounds, r, SkMatrix::kFill_ScaleToFit);
+    
+        SkAutoTUnref<SkShader> fShader(SkLightingShader::Create(
+                                                        fDiffuse,
+                                                        hemi ? fHemiNormalMap : fFrustumNormalMap, 
+                                                        fLight, fAmbient,
+                                                        &matrix));
 
         SkPaint paint;
         paint.setShader(fShader);
 
+        canvas->drawRect(r, paint);
+    }
+
+    void onDraw(SkCanvas* canvas) override {
         SkRect r = SkRect::MakeWH(SkIntToScalar(kTexSize), SkIntToScalar(kTexSize));
+        this->drawRect(canvas, r, true);
 
-        canvas->drawRect(r, paint);
+        r.offset(kGMSize - kTexSize, 0);
+        this->drawRect(canvas, r, false);
+
+        r.offset(0, kGMSize - kTexSize);
+        this->drawRect(canvas, r, true);
+
+        r.offset(kTexSize - kGMSize, 0);
+        this->drawRect(canvas, r, false);
     }
 
 private:
     static const int kTexSize = 128;
+    static const int kGMSize  = 512;
 
-    SkBitmap fDiffuse;
-    SkBitmap fNormalMap;
+    SkBitmap                fDiffuse;
+    SkBitmap                fHemiNormalMap;
+    SkBitmap                fFrustumNormalMap;
+
+    SkLightingShader::Light fLight;
+    SkColor                 fAmbient;
 
     typedef GM INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 DEF_GM( return SkNEW(LightingShaderGM); )
 
 }