adding new GM to demostrate new shadows

gm/shadowmaps.cpp

Index: gm/shadowmaps.cpp
diff --git a/gm/shadowmaps.cpp b/gm/shadowmaps.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..4a0f88ec91be1debe1ed7e016209c5c780089aa1
--- /dev/null
+++ b/gm/shadowmaps.cpp
@@ -0,0 +1,410 @@
+/*
+ * Copyright 2016 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 "SkPaintFilterCanvas.h"
+#include "SkPathEffect.h"
+#include "SkPictureRecorder.h"
+#include "SkShadowShader.h"
+#include "SkSurface.h"
+
+#ifdef SK_EXPERIMENTAL_SHADOWING
+
+static sk_sp<SkShader> make_shadow_shader(sk_sp<SkImage> povDepth,
+                                          sk_sp<SkImage> diffuse,
+                                          sk_sp<SkLights> lights) {
+
+    sk_sp<SkShader> povDepthShader = povDepth->makeShader(SkShader::kClamp_TileMode,
+                                                          SkShader::kClamp_TileMode);
+
+    sk_sp<SkShader> diffuseShader = diffuse->makeShader(SkShader::kClamp_TileMode,
+                                                        SkShader::kClamp_TileMode);
+
+    return SkShadowShader::Make(std::move(povDepthShader),
+                                std::move(diffuseShader),
+                                std::move(lights),
+                                diffuse->width(), diffuse->height());
+}
+
+static sk_sp<SkPicture> make_test_picture(int width, int height) {
+    SkPictureRecorder recorder;
+
+    // LONG RANGE TODO: eventually add SkBBHFactory (bounding box factory)
+    SkCanvas* canvas = recorder.beginRecording(SkRect::MakeIWH(width, height));
+
+    SkASSERT(canvas->getTotalMatrix().isIdentity());
+    SkPaint paint;
+    paint.setColor(SK_ColorGRAY);
+
+    // LONG RANGE TODO: tag occluders
+    // LONG RANGE TODO: track number of IDs we need (hopefully less than 256)
+    //                  and determinate the mapping from z to id
+
+    // universal receiver, "ground"
+    canvas->drawRect(SkRect::MakeIWH(width, height), paint);
+
+    // TODO: Maybe add the ID here along with the depth
+
+    paint.setColor(0xFFEE8888);
+
+    canvas->translateZ(80);
+    canvas->drawRect(SkRect::MakeLTRB(200,150,350,300), paint);
+
+    paint.setColor(0xFF88EE88);
+
+    canvas->translateZ(80);
+    canvas->drawRect(SkRect::MakeLTRB(150,200,300,350), paint);
+
+    paint.setColor(0xFF8888EE);
+
+    canvas->translateZ(80);
+    canvas->drawRect(SkRect::MakeLTRB(100,100,250,250), paint);
+    // TODO: Add an assert that Z order matches painter's order
+    // TODO: think about if the Z-order always matching painting order is too strict
+
+    return recorder.finishRecordingAsPicture();
+}
+
+namespace skiagm {
+
+/*  We override the onFilter method to draw depths into the canvas
+ *  depending on the current draw depth of the canvas, throwing out
+ *  the actual draw color.
+ */
+class SkShadowPaintFilterCanvas : public SkPaintFilterCanvas {
+public:
+
+    SkShadowPaintFilterCanvas(SkCanvas* canvas) : INHERITED(canvas) { }
+
+    // TODO use a shader instead
+    bool onFilter(SkTCopyOnFirstWrite<SkPaint>* paint, Type type) const override {
+        if (*paint) {
+            int z = this->getZ();
+            SkASSERT(z <= 0xFF && z >= 0x00);
+
+            SkPaint newPaint;
+            newPaint.setPathEffect(sk_ref_sp<SkPathEffect>((*paint)->getPathEffect()));
+
+            SkColor color = 0xFF000000; // init color to opaque black
+            color |= z; // Put the index into the blue component
+            newPaint.setColor(color);
+
+            *paint->writable() = newPaint;
+        }
+
+        return true;
+    }
+
+    void onDrawPicture(const SkPicture* picture, const SkMatrix* matrix, const SkPaint* paint) {
+        SkTCopyOnFirstWrite<SkPaint> filteredPaint(paint);
+        if (this->onFilter(&filteredPaint, kPicture_Type)) {
+            // we directly call SkCanvas's onDrawPicture because calling the one
+            // that INHERITED has (SkPaintFilterCanvas) leads to wrong behavior
+            this->SkCanvas::onDrawPicture(picture, matrix, filteredPaint);
+        }
+    }
+
+    void updateMatrix() {
+        this->save();
+
+        // When we use the SkShadowPaintFilterCanvas, we can only render
+        // one depth map at a time. Thus, we leave it up to the user to
+        // set SkLights to only contain (or contain at the first position)
+        // the light they intend to use for the current depth rendering.
+
+        if (fLights->numLights() > 0 &&
+            this->fLights->light(0).type() == SkLights::Light::kDirectional_LightType) {
+            SkVector3 lightDir = this->fLights->light(0).dir();
+            SkScalar x = lightDir.fX * this->getZ();
+            SkScalar y = lightDir.fY * this->getZ();
+
+            this->translate(x, y);
+        }
+
+    }
+
+    void onDrawPaint(const SkPaint& paint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawPaint(paint);
+        this->restore();
+    }
+
+    void onDrawPoints(PointMode mode, size_t count, const SkPoint pts[],
+                      const SkPaint& paint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawPoints(mode, count, pts, paint);
+        this->restore();
+    }
+
+    void onDrawRect(const SkRect& rect, const SkPaint& paint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawRect(rect, paint);
+        this->restore();
+    }
+
+    void onDrawRRect(const SkRRect& rrect, const SkPaint& paint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawRRect(rrect, paint);
+        this->restore();
+    }
+
+    void onDrawDRRect(const SkRRect& outer, const SkRRect& inner,
+                      const SkPaint& paint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawDRRect(outer, inner, paint);
+        this->restore();
+    }
+
+    void onDrawOval(const SkRect& rect, const SkPaint& paint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawOval(rect, paint);
+        this->restore();
+    }
+
+    void onDrawPath(const SkPath& path, const SkPaint& paint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawPath(path, paint);
+        this->restore();
+    }
+
+    void onDrawBitmap(const SkBitmap& bm, SkScalar left, SkScalar top,
+                      const SkPaint* paint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawBitmap(bm, left, top, paint);
+        this->restore();
+    }
+
+    void onDrawBitmapRect(const SkBitmap& bm, const SkRect* src, const SkRect& dst,
+                          const SkPaint* paint, SrcRectConstraint constraint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawBitmapRect(bm, src, dst, paint, constraint);
+        this->restore();
+    }
+
+    void onDrawBitmapNine(const SkBitmap& bm, const SkIRect& center,
+                          const SkRect& dst, const SkPaint* paint) {
+        this->updateMatrix();
+        this->INHERITED::onDrawBitmapNine(bm, center, dst, paint);
+        this->restore();
+    }
+
+    void onDrawImage(const SkImage* image, SkScalar left, SkScalar top,
+                     const SkPaint* paint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawImage(image, left, top, paint);
+        this->restore();
+    }
+
+    void onDrawImageRect(const SkImage* image, const SkRect* src, const SkRect& dst,
+                         const SkPaint* paint, SrcRectConstraint constraint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawImageRect(image, src, dst, paint, constraint);
+        this->restore();
+    }
+
+    void onDrawImageNine(const SkImage* image, const SkIRect& center,
+                         const SkRect& dst, const SkPaint* paint) {
+        this->updateMatrix();
+        this->INHERITED::onDrawImageNine(image, center, dst, paint);
+        this->restore();
+    }
+
+    void onDrawVertices(VertexMode vmode, int vertexCount, const SkPoint vertices[],
+                        const SkPoint texs[], const SkColor colors[], SkXfermode* xmode,
+                        const uint16_t indices[], int indexCount, const SkPaint& paint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawVertices(vmode, vertexCount, vertices, texs, colors,
+                                        xmode, indices, indexCount, paint);
+        this->restore();
+    }
+
+    void onDrawPatch(const SkPoint cubics[], const SkColor colors[], const SkPoint texCoords[],
+                     SkXfermode* xmode, const SkPaint& paint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawPatch(cubics, colors, texCoords, xmode, paint);
+        this->restore();
+    }
+
+    void onDrawText(const void* text, size_t byteLength,
+                    SkScalar x, SkScalar y, const SkPaint& paint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawText(text, byteLength, x, y, paint);
+        this->restore();
+    }
+
+    void onDrawPosText(const void* text, size_t byteLength,
+                       const SkPoint pos[], const SkPaint& paint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawPosText(text, byteLength, pos, paint);
+        this->restore();
+    }
+
+    void onDrawPosTextH(const void* text, size_t byteLength, const SkScalar xpos[],
+                        SkScalar constY, const SkPaint& paint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawPosTextH(text, byteLength, xpos, constY, paint);
+        this->restore();
+    }
+
+    void onDrawTextOnPath(const void* text, size_t byteLength, const SkPath& path,
+                          const SkMatrix* matrix, const SkPaint& paint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawTextOnPath(text, byteLength, path, matrix, paint);
+        this->restore();
+    }
+
+    void onDrawTextRSXform(const void* text, size_t byteLength, const SkRSXform xform[],
+                           const SkRect* cull, const SkPaint& paint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawTextRSXform(text, byteLength, xform, cull, paint);
+        this->restore();
+    }
+
+    void onDrawTextBlob(const SkTextBlob* blob, SkScalar x, SkScalar y,
+                        const SkPaint& paint) override {
+        this->updateMatrix();
+        this->INHERITED::onDrawTextBlob(blob, x, y, paint);
+        this->restore();
+    }
+
+private:
+    typedef SkPaintFilterCanvas INHERITED;
+};
+
+class ShadowMapsGM : public GM {
+public:
+    ShadowMapsGM() {
+        this->setBGColor(sk_tool_utils::color_to_565(0xFFCCCCCC));
+    }
+
+    void onOnceBeforeDraw() override {
+        // Create a light set consisting of
+        //   - bluish directional light pointing more right than down
+        //   - reddish directional light pointing more down than right
+        //   - soft white ambient light
+
+        SkLights::Builder builder;
+        builder.add(SkLights::Light(SkColor3f::Make(0.2f, 0.3f, 0.4f),
+                                    SkVector3::Make(0.2f, 0.1f, 1.0f)));
+        builder.add(SkLights::Light(SkColor3f::Make(0.4f, 0.3f, 0.2f),
+                                    SkVector3::Make(0.1f, 0.2f, 1.0f)));
+        builder.add(SkLights::Light(SkColor3f::Make(0.4f, 0.4f, 0.4f)));
+        fLights = builder.finish();
+    }
+
+protected:
+    static const int kWidth = 400;
+    static const int kHeight = 400;
+
+    SkString onShortName() override {
+        return SkString("shadowmaps");
+    }
+
+    SkISize onISize() override {
+        return SkISize::Make(kWidth, kHeight);
+    }
+
+    void onDraw(SkCanvas* canvas) override {
+        // This picture stores the picture of the scene.
+        // It's used to generate the depth maps.
+        sk_sp<SkPicture> pic(make_test_picture(kWidth, kHeight));
+
+        for (int i = 0; i < fLights->numLights(); ++i) {
+            // skip over ambient lights; they don't cast shadows
+            if (SkLights::Light::kAmbient_LightType == fLights->light(i).type()) {
+                continue;
+            }
+            // TODO: compute the correct size of the depth map from the light properties
+            // TODO: maybe add a kDepth_8_SkColorType
+
+            SkImageInfo info = SkImageInfo::Make(kWidth, kHeight,
+                                                 kBGRA_8888_SkColorType,
+                                                 kOpaque_SkAlphaType);
+
+            // Create a new surface (that matches the backend of canvas)
+            // for each shadow map
+            sk_sp<SkSurface> surf(canvas->makeSurface(info));
+
+            // Wrap another SPFCanvas around the surface
+            sk_sp<SkShadowPaintFilterCanvas> depthMapCanvas =
+                    sk_make_sp<SkShadowPaintFilterCanvas>(surf->getCanvas());
+
+            // set the depth map canvas to have the light we're drawing.
+            SkLights::Builder builder;
+            builder.add(fLights->light(i));
+            sk_sp<SkLights> curLight = builder.finish();
+
+            depthMapCanvas->setLights(std::move(curLight));
+            depthMapCanvas->drawPicture(pic);
+
+            fLights->light(i).setShadowMap(surf->makeImageSnapshot());
+        }
+
+        sk_sp<SkImage> povDepthMap;
+        sk_sp<SkImage> diffuseMap;
+
+        // TODO: pass the depth to the shader in vertices, or uniforms
+        //       so we don't have to render depth and color separately
+
+        // povDepthMap
+        {
+            SkLights::Builder builder;
+            builder.add(SkLights::Light(SkColor3f::Make(1.0f, 1.0f, 1.0f),
+                                        SkVector3::Make(0.0f, 0.0f, 1.0f)));
+            sk_sp<SkLights> povLight = builder.finish();
+
+            SkImageInfo info = SkImageInfo::Make(kWidth, kHeight,
+                                                 kBGRA_8888_SkColorType,
+                                                 kOpaque_SkAlphaType);
+
+            // Create a new surface (that matches the backend of canvas)
+            // to create the povDepthMap
+            sk_sp<SkSurface> surf(canvas->makeSurface(info));
+
+            // Wrap another SPFCanvas around the surface
+            sk_sp<SkShadowPaintFilterCanvas> depthMapCanvas =
+                    sk_make_sp<SkShadowPaintFilterCanvas>(surf->getCanvas());
+
+            // set the depth map canvas to have the light as the user's POV
+            depthMapCanvas->setLights(std::move(povLight));
+
+            depthMapCanvas->drawPicture(pic);
+
+            povDepthMap = surf->makeImageSnapshot();
+        }
+
+        // diffuseMap
+        {
+            SkImageInfo info = SkImageInfo::Make(kWidth, kHeight,
+                                                 kBGRA_8888_SkColorType,
+                                                 kOpaque_SkAlphaType);
+
+            sk_sp<SkSurface> surf(canvas->makeSurface(info));
+            surf->getCanvas()->drawPicture(pic);
+
+            diffuseMap = surf->makeImageSnapshot();
+        }
+
+        SkPaint paint;
+        paint.setShader(make_shadow_shader(std::move(povDepthMap), std::move(diffuseMap), fLights));
+
+        canvas->drawRect(SkRect::MakeIWH(kWidth, kHeight), paint);
+    }
+
+private:
+    sk_sp<SkLights> fLights;
+
+    typedef GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+DEF_GM(return new ShadowMapsGM;)
+}
+
+#endif