GPU Gradients

src/effects/gradients/SkGradientShader.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkGradientShaderPriv.h"
 #include "SkLinearGradient.h"
 #include "SkRadialGradient.h"
@@ skipping 814 matching lines @@
 
 GrGLGradientEffect::GrGLGradientEffect(const GrBackendEffectFactory& factory)
     : INHERITED(factory)
     , fCachedYCoord(SK_ScalarMax)
     , fFSYUni(GrGLUniformManager::kInvalidUniformHandle)
     , fEffectMatrix(kCoordsType) {
 }
 
 GrGLGradientEffect::~GrGLGradientEffect() { }
 
-void GrGLGradientEffect::emitYCoordUniform(GrGLShaderBuilder* builder) {
-    fFSYUni = builder->addUniform(GrGLShaderBuilder::kFragment_ShaderType,
-                                  kFloat_GrSLType, "GradientYCoordFS");
+void GrGLGradientEffect::emitUniforms(GrGLShaderBuilder* builder, EffectKey key) {
+
+    if (is2Color(key)) { // 2 Color case
+        fColorStartUni = builder->addUniform(GrGLShaderBuilder::kFragment_ShaderType,
+                                             kVec4f_GrSLType, "GradientStartColor");
+        fColorEndUni = builder->addUniform(GrGLShaderBuilder::kFragment_ShaderType,
+                                           kVec4f_GrSLType, "GradientEndColor");
+        
+    } else if (is3Color(key)){ // 3 Color Case
+        fColorStartUni = builder->addUniform(GrGLShaderBuilder::kFragment_ShaderType,
+                                             kVec4f_GrSLType, "GradientStartColor");
+        fColorMidUni = builder->addUniform(GrGLShaderBuilder::kFragment_ShaderType,
+                                           kVec4f_GrSLType, "GradientMidColor");
+        fColorEndUni = builder->addUniform(GrGLShaderBuilder::kFragment_ShaderType,
+                                             kVec4f_GrSLType, "GradientEndColor");
+
+    } else { // if not a fast case
+        fFSYUni = builder->addUniform(GrGLShaderBuilder::kFragment_ShaderType,
+                                      kFloat_GrSLType, "GradientYCoordFS");
+    }
 }
 
 void GrGLGradientEffect::setData(const GrGLUniformManager& uman,
                                  const GrDrawEffect& drawEffect) {
+
     const GrGradientEffect& e = drawEffect.castEffect<GrGradientEffect>();
-    const GrTexture* texture = e.texture(0);
-    fEffectMatrix.setData(uman, e.getMatrix(), drawEffect, texture);
 
-    SkScalar yCoord = e.getYCoord();
-    if (yCoord != fCachedYCoord) {
-        uman.set1f(fFSYUni, yCoord);
-        fCachedYCoord = yCoord;
+    if (is2Color(e)){
+        uman.set4f(fColorStartUni, 1.f, 1.f, 1.f, 1.f);
+        uman.set4f(fColorEndUni, 0.f, 0.f, 0.f, 1.f);
+
+    } else if (is3Color(e)){
+        uman.set4f(fColorStartUni, 1.f, 1.f, 1.f, 1.f);
+        uman.set4f(fColorMidUni, 1.f, 0.f, 0.f, 0.f);
+        uman.set4f(fColorEndUni, 1.f, 1.f, 1.f, 1.f);
+    } else {
+        const GrTexture* texture = e.texture(0);
+        fEffectMatrix.setData(uman, e.getMatrix(), drawEffect, texture);
+        
+        SkScalar yCoord = e.getYCoord();
+        if (yCoord != fCachedYCoord) {
+            uman.set1f(fFSYUni, yCoord);
+            fCachedYCoord = yCoord;
+        }
     }
 }
 
+
 GrGLEffect::EffectKey GrGLGradientEffect::GenMatrixKey(const GrDrawEffect& drawEffect) {

[bsalomon, 2013/08/13 14:28:37]

Since this is no longer just doing the matrix it should probably be renamed to
something more accurate. GenMatrixAndColorTypeKey(), GenBaseGradientKey(), ...

[dierk, 2013/08/13 19:50:17]

Done.

     const GrGradientEffect& e = drawEffect.castEffect<GrGradientEffect>();
-    const GrTexture* texture = e.texture(0);
-    return GrGLEffectMatrix::GenKey(e.getMatrix(), drawEffect, kCoordsType, texture);
+    const GrTexture* texture = NULL;
+    
+    if (e.numColors > 3){
+        texture = e.texture(0);
+    }
+    
+    EffectKey key = GrGLEffectMatrix::GenKey(e.getMatrix(), drawEffect, kCoordsType, texture);

[bsalomon, 2013/08/13 14:28:37]

Should probably only call GrGLEffectMatrix::GenKey inside the above if.

[dierk, 2013/08/13 19:50:17]

Why is that? I thought I needed the matrix key to be generated in the 2 and 3
color cases as well (hence why I was only seeing the end color of the mix
before)

On 2013/08/13 14:28:37, bsalomon wrote:

+
+    if (is2Color(e)) {
+        key = key | 0x4000;
+    } else if (is3Color(e)){
+        key = key | 0x6000;
+    }
+
+    return key;
 }
 
 void GrGLGradientEffect::setupMatrix(GrGLShaderBuilder* builder,
                                      EffectKey key,
                                      const char** fsCoordName,
                                      const char** vsVaryingName,
                                      GrSLType* vsVaryingType) {
     fEffectMatrix.emitCodeMakeFSCoords2D(builder,
                                          key & kMatrixKeyMask,
                                          fsCoordName,
                                          vsVaryingName,
                                          vsVaryingType);
 }
 
-void GrGLGradientEffect::emitColorLookup(GrGLShaderBuilder* builder,
-                                         const char* gradientTValue,
-                                         const char* outputColor,
-                                         const char* inputColor,
-                                         const GrGLShaderBuilder::TextureSampler& sampler) {
-
-    builder->fsCodeAppendf("\tvec2 coord = vec2(%s, %s);\n",
-                           gradientTValue,
-                           builder->getUniformVariable(fFSYUni).c_str());
-    builder->fsCodeAppendf("\t%s = ", outputColor);
-    builder->appendTextureLookupAndModulate(GrGLShaderBuilder::kFragment_ShaderType,
-                                            inputColor,
-                                            sampler,
-                                            "coord");
-    builder->fsCodeAppend(";\n");
+void GrGLGradientEffect::emitColor(GrGLShaderBuilder* builder,
+                                   const char* gradientTValue,
+                                   EffectKey key,
+                                   const char* outputColor,
+                                   const char* inputColor,
+                                   const GrGLShaderBuilder::TextureSamplerArray& samplers) {
+    if (is2Color(key)){
+        builder->fsCodeAppendf("\t%s = mix(%s, %s, %s);\n",
+                               outputColor,
+                               builder->getUniformVariable(fColorStartUni).c_str(),
+                               builder->getUniformVariable(fColorEndUni).c_str(),
+                               gradientTValue);
+    } else if (is3Color(key)){
+        //same as 2 color for now... causes bug from unused UNI
+        builder->fsCodeAppendf("\t%s = mix(%s, %s, %s);\n",
+                               outputColor,
+                               builder->getUniformVariable(fColorStartUni).c_str(),
+                               builder->getUniformVariable(fColorEndUni).c_str(),
+                               gradientTValue);
+    } else {
+        builder->fsCodeAppendf("\tvec2 coord = vec2(%s, %s);\n",
+                               gradientTValue,
+                               builder->getUniformVariable(fFSYUni).c_str());
+        builder->fsCodeAppendf("\t%s = ", outputColor);
+        builder->appendTextureLookupAndModulate(GrGLShaderBuilder::kFragment_ShaderType,
+                                                inputColor,
+                                                samplers[0],
+                                                "coord");
+        builder->fsCodeAppend(";\n");
+    }
 }
 
 /////////////////////////////////////////////////////////////////////
 
 GrGradientEffect::GrGradientEffect(GrContext* ctx,
                                    const SkGradientShaderBase& shader,
                                    const SkMatrix& matrix,
                                    SkShader::TileMode tileMode) {
-    // TODO: check for simple cases where we don't need a texture:
-    //GradientInfo info;
-    //shader.asAGradient(&info);
-    //if (info.fColorCount == 2) { ...
 
     fMatrix = matrix;
 
     SkBitmap bitmap;
     shader.getGradientTableBitmap(&bitmap);
 
     fIsOpaque = shader.isOpaque();
 
-    GrTextureStripAtlas::Desc desc;
-    desc.fWidth  = bitmap.width();
-    desc.fHeight = 32;
-    desc.fRowHeight = bitmap.height();
-    desc.fContext = ctx;
-    desc.fConfig = SkBitmapConfig2GrPixelConfig(bitmap.config());
-    fAtlas = GrTextureStripAtlas::GetAtlas(desc);
-    GrAssert(NULL != fAtlas);
+    // TODO: check for simple cases where we don't need a texture:
+    SkShader::GradientInfo info;
+    SkScalar pos[3] = {0};
 
-    // We always filter the gradient table. Each table is one row of a texture, so always y-clamp.
-    GrTextureParams params;
-    params.setFilterMode(GrTextureParams::kBilerp_FilterMode);
-    params.setTileModeX(tileMode);
+    info.fColorCount = 3;
+    info.fColors = NULL;
+    info.fColorOffsets = &pos[0];
+    shader.asAGradient(&info);
 
-    fRow = fAtlas->lockRow(bitmap);
-    if (-1 != fRow) {
-        fYCoord = fAtlas->getYOffset(fRow) + SK_ScalarHalf *
-                  fAtlas->getVerticalScaleFactor();
-        fTextureAccess.reset(fAtlas->getTexture(), params);
+    if (info.fColorCount == 2) { // if 2 color

[bsalomon, 2013/08/13 14:28:37]

Style nit: 2 == info.fColorCount

[dierk, 2013/08/13 19:50:17]

Done.

+        fRow = -1;
+        numColors = 2;
+
+    } else if (info.fColorCount == 3 && (abs(pos[1] - 0.5) < 0.01)) { // if 3 color symmetric

[bsalomon, 2013/08/13 14:28:37]

I think there is an abs for SkScalar.

[dierk, 2013/08/13 19:50:17]

Done.

+        fRow = -1;
+        numColors = 3;
+
     } else {
-        GrTexture* texture = GrLockAndRefCachedBitmapTexture(ctx, bitmap, &params);
-        fTextureAccess.reset(texture, params);
-        fYCoord = SK_ScalarHalf;
+        numColors = 4;

[bsalomon, 2013/08/13 14:28:37]

? This at least deserves a comment since the number of colors is not really
necessarily 4.

[dierk, 2013/08/13 19:50:17]

Done.

+        
+        GrTextureStripAtlas::Desc desc;
+        desc.fWidth  = bitmap.width();
+        desc.fHeight = 32;
+        desc.fRowHeight = bitmap.height();
+        desc.fContext = ctx;
+        desc.fConfig = SkBitmapConfig2GrPixelConfig(bitmap.config());
+        fAtlas = GrTextureStripAtlas::GetAtlas(desc);
+        GrAssert(NULL != fAtlas);
 
-        // Unlock immediately, this is not great, but we don't have a way of
-        // knowing when else to unlock it currently, so it may get purged from
-        // the cache, but it'll still be ref'd until it's no longer being used.
-        GrUnlockAndUnrefCachedBitmapTexture(texture);
+        // We always filter the gradient table. Each table is one row of a texture, so always y-clamp.
+        GrTextureParams params;
+        params.setFilterMode(GrTextureParams::kBilerp_FilterMode);
+        params.setTileModeX(tileMode);
+
+        fRow = fAtlas->lockRow(bitmap);
+        if (-1 != fRow) {
+            fYCoord = fAtlas->getYOffset(fRow) + SK_ScalarHalf *
+            fAtlas->getVerticalScaleFactor();
+            fTextureAccess.reset(fAtlas->getTexture(), params);
+        } else {
+            GrTexture* texture = GrLockAndRefCachedBitmapTexture(ctx, bitmap, &params);
+            fTextureAccess.reset(texture, params);
+            fYCoord = SK_ScalarHalf;
+
+            // Unlock immediately, this is not great, but we don't have a way of
+            // knowing when else to unlock it currently, so it may get purged from
+            // the cache, but it'll still be ref'd until it's no longer being used.
+            GrUnlockAndUnrefCachedBitmapTexture(texture);
+        }
+        this->addTextureAccess(&fTextureAccess);
     }
-    this->addTextureAccess(&fTextureAccess);
 }
 
 GrGradientEffect::~GrGradientEffect() {
     if (this->useAtlas()) {
         fAtlas->unlockRow(fRow);
     }
 }
 
 bool GrGradientEffect::onIsEqual(const GrEffect& effect) const {
     const GrGradientEffect& s = CastEffect<GrGradientEffect>(effect);
     return fTextureAccess.getTexture() == s.fTextureAccess.getTexture()  &&
            fTextureAccess.getParams().getTileModeX() ==
                 s.fTextureAccess.getParams().getTileModeX() &&
            this->useAtlas() == s.useAtlas() &&

[bsalomon, 2013/08/13 14:28:37]

Is useAtlas() equivalent to NULL == fTextureAccess.getTexture()? If so, we
already checked that.

[dierk, 2013/08/13 19:50:17]

I'm not sure. It was already there.

The useAtlas() function returns true if fRow == -1, is that the same?

On 2013/08/13 14:28:37, bsalomon wrote:

[bsalomon, 2013/08/13 21:07:52]

It should be. When you update the color comparison here we should probably add
some asserts that all of our assumptions are true around the consistency of
fRow, getTexture(), and the number of colors.

            fYCoord == s.getYCoord() &&
-           fMatrix.cheapEqualTo(s.getMatrix());
+           fMatrix.cheapEqualTo(s.getMatrix())
+           && this->numColors == s.numColors; // do I need this check?

[bsalomon, 2013/08/13 14:28:37]

Yes, you probably need to compare the colors too for the 2/3 cases. This is done
implicitly for the texture case by checking that they refer to the same row of
the same texture.

[dierk, 2013/08/13 19:50:17]

Will add once colors are piped in.

On 2013/08/13 14:28:37, bsalomon wrote:

 }
 
 void GrGradientEffect::getConstantColorComponents(GrColor* color, uint32_t* validFlags) const {
     if (fIsOpaque && (kA_GrColorComponentFlag & *validFlags) && 0xff == GrColorUnpackA(*color)) {
         *validFlags = kA_GrColorComponentFlag;
     } else {
         *validFlags = 0;
     }
 }
 
@@ skipping 15 matching lines @@
             (*stops)[i] = stop;
             stop = i < outColors - 1 ? stop + random->nextUScalar1() * (1.f - stop) : 1.f;
         }
     }
     *tm = static_cast<SkShader::TileMode>(random->nextULessThan(SkShader::kTileModeCount));
 
     return outColors;
 }
 
 #endif