SkLS accepts nullptr for pointer args, handles alpha accurately, has new GM

gm/lightingshader2.cpp

+/*

[robertphillips, 2016/07/11 14:02:04]

2016

[dvonbeck, 2016/07/11 19:37:29]

Done.

+ * 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 "SkBitmapProcShader.h"
+#include "SkLightingShader.h"
+#include "SkNormalSource.h"
+#include "SkPoint3.h"
+#include "SkShader.h"
+
+// Create a truncated pyramid normal map
+static SkBitmap make_frustum_normalmap(int texSize) {
+    SkBitmap frustum;
+    frustum.allocN32Pixels(texSize, texSize);
+
+    sk_tool_utils::create_frustum_normal_map(&frustum, SkIRect::MakeWH(texSize, texSize));
+    return frustum;
+}
+
+namespace skiagm {
+
+// This GM exercises lighting shaders.

[robertphillips, 2016/07/11 14:02:04]

// more ...
// what does it do besides what the original GM does ?

[dvonbeck, 2016/07/11 19:37:29]

Done.

+class LightingShader2GM : public GM {
+public:
+    LightingShader2GM() {
+        this->setBGColor(sk_tool_utils::color_to_565(0xFFCCCCCC));
+
+        SkLights::Builder builder;
+
+        builder.add(SkLights::Light(SkColor3f::Make(1.0f, 1.0f, 1.0f),

[robertphillips, 2016/07/11 14:02:04]

normalize this so the reader has a better expectation of where it is?
Maybe make a named const version (e.g., kLightFromUpperRight) ?

[dvonbeck, 2016/07/11 19:37:29]

Done.

+                                    SkVector3::Make(1.0f, 0.5f, 0.6f)));
+        builder.add(SkLights::Light(SkColor3f::Make(0.2f, 0.2f, 0.2f)));
+
+        fLights = builder.finish();
+    }
+
+protected:

[robertphillips, 2016/07/11 14:02:04]

extra spaces ?

[dvonbeck, 2016/07/11 19:37:29]

Done.

+
+
+    SkString onShortName() override {
+        return SkString("lightingshader2");
+    }
+
+    SkISize onISize() override {
+        return SkISize::Make(kGMSize, kGMSize);
+    }
+
+    void onOnceBeforeDraw() override {

[robertphillips, 2016/07/11 14:02:04]

Can we create the lights in here too ?

[dvonbeck, 2016/07/11 19:37:28]

Done. Why?

[robertphillips, 2016/07/11 20:40:55]

The problem with doing stuff in the constructor is that the tooling creates all
the GMs up front. If you want to put a break point in the SkLights class and
then run an individual GM you're likely to get a lot of irrelevant breaks for
GMs that do stuff in their constructors. In general we try to do as little as
possible in the constructor.

+        fDiffuse = sk_tool_utils::create_checkerboard_bitmap(
+                                                        kTexSize, kTexSize,
+                                                        sk_tool_utils::color_to_565(0x0),
+                                                        sk_tool_utils::color_to_565(0xFF804020),
+                                                        8);
+
+        fNormalMap = make_frustum_normalmap(kTexSize);
+    }
+

[robertphillips, 2016/07/11 14:02:04]

// ... ?

[dvonbeck, 2016/07/11 19:37:29]

Done.

+    void positionCTM(SkCanvas *canvas, SkScalar scaleX, SkScalar scaleY, SkScalar rotate) const {
+        canvas->translate(kGMSize / 2.0f, kGMSize / 2.0f);
+        canvas->scale(scaleX, scaleY);
+        canvas->rotate(rotate);
+        canvas->translate(-kTexSize/2.0f, -kTexSize/2.0f);
+    }
+

[robertphillips, 2016/07/11 14:02:03]

Hmmm, there is a lot of duplicate code here. Can we add useDiffuseMap and
useNormapMap parameters and have only one draw function ?

[dvonbeck, 2016/07/11 19:37:29]

Done.

+    void drawRect(SkCanvas* canvas, const SkRect& r, SkScalar scaleX, SkScalar scaleY,
+                  SkScalar rotate) {

[robertphillips, 2016/07/11 14:02:04]

this-> 

[dvonbeck, 2016/07/11 19:37:29]

Done.

+        positionCTM(canvas, scaleX, scaleY, rotate);
+
+        SkRect bitmapBounds = SkRect::MakeIWH(fDiffuse.width(), fDiffuse.height());
+
+        SkMatrix matrix;
+        matrix.setRectToRect(bitmapBounds, r, SkMatrix::kFill_ScaleToFit);
+
+        const SkMatrix& ctm = canvas->getTotalMatrix();
+
+        SkPaint paint;
+        sk_sp<SkShader> normalMap = SkMakeBitmapShader(fNormalMap, SkShader::kClamp_TileMode,
+                                                       SkShader::kClamp_TileMode, &matrix, nullptr);
+        sk_sp<SkNormalSource> normalSource = SkNormalSource::MakeFromNormalMap(std::move(normalMap),
+                                                                               ctm);
+        sk_sp<SkShader> diffuseShader = SkMakeBitmapShader(fDiffuse, SkShader::kClamp_TileMode,
+                SkShader::kClamp_TileMode, &matrix, nullptr);
+        paint.setShader(SkLightingShader::Make(std::move(diffuseShader), std::move(normalSource),
+                                               fLights));
+
+        canvas->drawRect(r, paint);
+    }
+
+    void drawRectFromNullDiffuse(SkCanvas* canvas, const SkRect& r, SkScalar scaleX,
+                                 SkScalar scaleY, SkScalar rotate) {
+        positionCTM(canvas, scaleX, scaleY, rotate);
+
+        SkRect bitmapBounds = SkRect::MakeIWH(fDiffuse.width(), fDiffuse.height());
+
+        SkMatrix matrix;
+        matrix.setRectToRect(bitmapBounds, r, SkMatrix::kFill_ScaleToFit);
+
+        const SkMatrix& ctm = canvas->getTotalMatrix();
+
+        SkPaint paint;
+        sk_sp<SkShader> normalMap = SkMakeBitmapShader(fNormalMap, SkShader::kClamp_TileMode,
+                                                       SkShader::kClamp_TileMode, &matrix, nullptr);
+        sk_sp<SkNormalSource> normalSource = SkNormalSource::MakeFromNormalMap(std::move(normalMap),
+                                                                               ctm);
+        paint.setShader(SkLightingShader::Make(nullptr, std::move(normalSource),
+                                               fLights));
+        paint.setColor(SK_ColorGREEN);
+
+        canvas->drawRect(r, paint);
+    }
+
+    void drawRectFromNullNormalSource(SkCanvas* canvas, const SkRect& r, SkScalar scaleX,
+                                      SkScalar scaleY, SkScalar rotate) {
+        positionCTM(canvas, scaleX, scaleY, rotate);
+
+        SkRect bitmapBounds = SkRect::MakeIWH(fDiffuse.width(), fDiffuse.height());
+
+        SkMatrix matrix;
+        matrix.setRectToRect(bitmapBounds, r, SkMatrix::kFill_ScaleToFit);
+
+        SkPaint paint;
+        sk_sp<SkShader> diffuseShader = SkMakeBitmapShader(fDiffuse, SkShader::kClamp_TileMode,
+                SkShader::kClamp_TileMode, &matrix, nullptr);
+        paint.setShader(SkLightingShader::Make(std::move(diffuseShader), nullptr, fLights));
+
+        canvas->drawRect(r, paint);
+    }
+
+    void onDraw(SkCanvas* canvas) override {

[robertphillips, 2016/07/11 14:02:04]

one line ?

[dvonbeck, 2016/07/11 19:37:28]

Done.

+        SkRect r;
+        r = SkRect::MakeWH(SkIntToScalar(kTexSize), SkIntToScalar(kTexSize));
+
+        canvas->save();

[robertphillips, 2016/07/11 14:02:04]

SK_ScalarSqrt2 ?

[dvonbeck, 2016/07/11 19:37:29]

Done.

+        canvas->translate(0.0f, -SkScalarSqrt(2.0f) * kTexSize);
+        this->drawRect(canvas, r, 1.0f, 1.0f, 45.f);
+        canvas->restore();
+
+        canvas->save();
+        canvas->translate(-SkScalarSqrt(2.0f) * kTexSize, -SkScalarSqrt(2.0f) * kTexSize);
+        this->drawRect(canvas, r, 1.2f, 1.2f, 0.f);
+        canvas->restore();
+
+        canvas->save();
+        canvas->translate(SkScalarSqrt(2.0f) * kTexSize, -SkScalarSqrt(2.0f) * kTexSize);
+        this->drawRect(canvas, r, 0.5f, 0.5f, 0.f);
+        canvas->restore();
+
+        canvas->save();
+        canvas->translate(-SkScalarSqrt(2.0f) * kTexSize, 0.0f);
+        this->drawRectFromNullDiffuse(canvas, r, 1.0f, 1.0f, 0.f);
+        canvas->restore();
+
+        canvas->save();
+        canvas->translate(SkScalarSqrt(2.0f) * kTexSize, 0.0f);
+        this->drawRectFromNullNormalSource(canvas, r, 1.0f, 1.0f, 0.f);
+        canvas->restore();
+    }
+
+private:
+    static const int kTexSize = 128;
+    static const int kGMSize  = 512;
+
+    SkBitmap        fDiffuse;
+    SkBitmap        fNormalMap;
+
+    sk_sp<SkLights> fLights;
+
+    typedef GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+DEF_GM(return new LightingShader2GM;)
+}