Making a sample for shadow maps for more intensive development

samplecode/SampleShadowing.cpp

Index: samplecode/SampleShadowing.cpp
diff --git a/samplecode/SampleShadowing.cpp b/samplecode/SampleShadowing.cpp
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+++ b/samplecode/SampleShadowing.cpp
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+/*
+ * 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 "SampleCode.h"
+#include "SkPictureRecorder.h"
+#include "SkShadowPaintFilterCanvas.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());
+}
+
+class ShadowingView : public SampleView {
+public:
+    ShadowingView() {
+
+        this->setBGColor(0xFFCCCCCC);
+        SkLights::Builder builder;
+        builder.add(SkLights::Light(SkColor3f::Make(0.2f, 0.3f, 0.4f),
+                                    SkVector3::Make(0.27f, 0.07f, 1.0f)));
+        builder.add(SkLights::Light(SkColor3f::Make(0.4f, 0.3f, 0.2f),
+                                    SkVector3::Make(0.03f, 0.27f, 1.0f)));
+        builder.add(SkLights::Light(SkColor3f::Make(0.4f, 0.4f, 0.4f)));
+        fLights = builder.finish();
+
+        fTestRects[0].fColor = 0xFFEE8888;
+        fTestRects[0].fDepth = 80;
+        fTestRects[0].fGeometry = SkRect::MakeLTRB(200,150,350,300);
+
+        fTestRects[1].fColor = 0xFF88EE88;
+        fTestRects[1].fDepth = 160;
+        fTestRects[1].fGeometry = SkRect::MakeLTRB(150,200,300,350);
+
+        fTestRects[2].fColor = 0xFF8888EE;
+        fTestRects[2].fDepth = 240;
+        fTestRects[2].fGeometry = SkRect::MakeLTRB(100,100,250,250);
+
+        fSceneChanged = true;
+        fLightsChanged = true;
+
+        fSelectedRect = -1;
+        fMoveLight = false;
+    }
+
+protected:
+    bool onQuery(SkEvent *evt) override {
+        if (SampleCode::TitleQ(*evt)) {
+            SampleCode::TitleR(evt, "shadowing");
+            return true;
+        }
+
+        SkUnichar uni;
+        if (SampleCode::CharQ(*evt, &uni)) {
+            switch (uni) {
+                case 'L':
+                    fMoveLight = !fMoveLight;
+                    break;
+                default:
+                    break;
+            }
+        }
+        return this->INHERITED::onQuery(evt);
+    }
+
+    sk_sp<SkPicture> makeTestPicture(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);
+
+        for (int i = 0; i < kNumTestRects; i++) {
+            paint.setColor(fTestRects[i].fColor);
+            if (i == 0) {
+                canvas->translateZ(fTestRects[0].fDepth);
+            } else {
+                canvas->translateZ(fTestRects[i].fDepth - fTestRects[i-1].fDepth);
+            }
+            canvas->drawRect(fTestRects[i].fGeometry, paint);
+        }
+
+        return recorder.finishRecordingAsPicture();
+    }
+
+    void updateDepthMaps(SkCanvas *canvas) {
+        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: maybe add a kDepth_8_SkColorType when vertices have depth
+            // assume max depth is 255.
+            // TODO: find actual max depth of picture
+            SkISize shMapSize = SkShadowPaintFilterCanvas::
+                                ComputeDepthMapSize(fLights->light(i), 255, kWidth, kHeight);
+
+            SkImageInfo info = SkImageInfo::Make(shMapSize.fWidth, shMapSize.fHeight,
+                                                 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(fPicture);
+
+            fLights->light(i).setShadowMap(surf->makeImageSnapshot());
+        }
+    }
+
+    void updatePovDepthMap(SkCanvas* canvas) {
+        // TODO: pass the depth to the shader in vertices, or uniforms
+        //       so we don't have to render depth and color separately
+
+        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(fPicture);
+
+        fPovDepthMap = surf->makeImageSnapshot();
+    }
+
+    void updateDiffuseMap(SkCanvas* canvas) {
+        SkImageInfo info = SkImageInfo::Make(kWidth, kHeight,
+                                             kBGRA_8888_SkColorType,
+                                             kOpaque_SkAlphaType);
+
+        sk_sp<SkSurface> surf(canvas->makeSurface(info));
+        surf->getCanvas()->drawPicture(fPicture);
+
+        fDiffuseMap = surf->makeImageSnapshot();
+    }
+
+    void onDrawContent(SkCanvas *canvas) override {
+        if (fSceneChanged || !fPovDepthMap) {
+            fPicture = this->makeTestPicture(kWidth, kHeight);
+            this->updateDepthMaps(canvas);
+            this->updatePovDepthMap(canvas);
+            this->updateDiffuseMap(canvas);
+        }
+
+        if (fLightsChanged) {
+            this->updateDepthMaps(canvas);
+        }
+
+        if (fSceneChanged || fLightsChanged || !fShadowShader) {
+            fShadowShader = make_shadow_shader(fPovDepthMap, fDiffuseMap, fLights);
+        }
+
+        SkPaint paint;
+        paint.setShader(fShadowShader);
+
+        canvas->drawRect(SkRect::MakeIWH(kWidth, kHeight), paint);
+    }
+
+    SkView::Click* onFindClickHandler(SkScalar x, SkScalar y, unsigned modi) override {
+        return new SkView::Click(this);
+    }
+
+    bool onClick(Click *click) override {
+        SkScalar x = click->fCurr.fX;
+        SkScalar y = click->fCurr.fY;
+
+        SkScalar dx = x - click->fPrev.fX;
+        SkScalar dy = y - click->fPrev.fY;
+
+        if (fMoveLight) {
+            if (dx != 0 || dy != 0) {
+                float recipX = 1.0f / kWidth;
+                float recipY = 1.0f / kHeight;
+
+                SkLights::Builder builder;
+                builder.add(SkLights::Light(SkColor3f::Make(0.2f, 0.3f, 0.4f),
+                                            SkVector3::Make(0.12f + (200.0f - x) * recipX,
+                                                            -0.08f + (200.0f - y) * recipY,
+                                                            1.0f)));
+                builder.add(SkLights::Light(SkColor3f::Make(0.4f, 0.3f, 0.2f),
+                                            SkVector3::Make(-0.12f + (200.0f - x) * recipX,
+                                                            0.12f + (200.0f - y) * recipY,
+                                                            1.0f)));
+                builder.add(SkLights::Light(SkColor3f::Make(0.4f, 0.4f, 0.4f)));
+                fLights = builder.finish();
+
+                fLightsChanged = true;
+                this->inval(nullptr);
+            }
+            return true;
+        }
+
+        if (click->fState == Click::State::kUp_State) {
+            fSelectedRect = -1;
+            return true;
+        }
+
+        if (fSelectedRect > -1) {
+            fTestRects[fSelectedRect].fGeometry.offset(dx, dy);
+
+            fSceneChanged = true;
+            this->inval(nullptr);
+            return true;
+        }
+
+        // assume last elements are highest
+        for (int i = kNumTestRects - 1; i >= 0; i--) {
+            if (fTestRects[i].fGeometry.contains(SkRect::MakeXYWH(x, y, 1, 1))) {
+                fSelectedRect = i;
+                fTestRects[i].fGeometry.offset(dx, dy);
+
+                fSceneChanged = true;
+                this->inval(nullptr);
+                break;
+            }
+        }
+
+        return true;
+    }
+
+private:
+    static constexpr int kNumTestRects = 3;
+
+    static const int kWidth = 400;
+    static const int kHeight = 400;
+
+    struct {
+        SkRect  fGeometry;
+        int     fDepth;
+        SkColor fColor;
+    } fTestRects[kNumTestRects];
+
+    int fSelectedRect;
+    bool fMoveLight;
+
+    sk_sp<SkImage>   fPovDepthMap;
+    sk_sp<SkImage>   fDiffuseMap;
+    sk_sp<SkPicture> fPicture;
+    sk_sp<SkShader>  fShadowShader;
+
+    bool fSceneChanged;
+    bool fLightsChanged;
+
+    sk_sp<SkLights> fLights;
+
+    typedef SampleView INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+static SkView* MyFactory() { return new ShadowingView; }
+static SkViewRegister reg(MyFactory);
+
+#endif