Use all available texture units.

src/gpu/gl/GrGpuGL.cpp

Index: src/gpu/gl/GrGpuGL.cpp
diff --git a/src/gpu/gl/GrGpuGL.cpp b/src/gpu/gl/GrGpuGL.cpp
index 0c47060e4f5033454caf5b1748762a57a4c6eb47..83c91ba972075bbb60fb20265febf5b4c00ccda6 100644
--- a/src/gpu/gl/GrGpuGL.cpp
+++ b/src/gpu/gl/GrGpuGL.cpp
@@ -20,9 +20,6 @@ static const GrGLint  GR_INVAL_GLINT = ~0;
 #define GL_CALL(X) GR_GL_CALL(this->glInterface(), X)
 #define GL_CALL_RET(RET, X) GR_GL_CALL_RET(this->glInterface(), RET, X)
 
-// we use a spare texture unit to avoid
-// mucking with the state of any of the stages.
-static const int SPARE_TEX_UNIT = GrDrawState::kNumStages;
 
 #define SKIP_CACHE_CHECK    true
 
@@ -118,35 +115,6 @@ bool GrGpuGL::BlendCoeffReferencesConstant(GrBlendCoeff coeff) {
 
 static bool gPrintStartupSpew;
 
-static bool fbo_test(const GrGLInterface* gl, int w, int h) {
-
-    GR_GL_CALL(gl, ActiveTexture(GR_GL_TEXTURE0 + SPARE_TEX_UNIT));
-
-    GrGLuint testFBO;
-    GR_GL_CALL(gl, GenFramebuffers(1, &testFBO));
-    GR_GL_CALL(gl, BindFramebuffer(GR_GL_FRAMEBUFFER, testFBO));
-    GrGLuint testRTTex;
-    GR_GL_CALL(gl, GenTextures(1, &testRTTex));
-    GR_GL_CALL(gl, BindTexture(GR_GL_TEXTURE_2D, testRTTex));
-    // some implementations require texture to be mip-map complete before
-    // FBO with level 0 bound as color attachment will be framebuffer complete.
-    GR_GL_CALL(gl, TexParameteri(GR_GL_TEXTURE_2D,
-                                 GR_GL_TEXTURE_MIN_FILTER,
-                                 GR_GL_NEAREST));
-    GR_GL_CALL(gl, TexImage2D(GR_GL_TEXTURE_2D, 0, GR_GL_RGBA, w, h,
-                              0, GR_GL_RGBA, GR_GL_UNSIGNED_BYTE, NULL));
-    GR_GL_CALL(gl, BindTexture(GR_GL_TEXTURE_2D, 0));
-    GR_GL_CALL(gl, FramebufferTexture2D(GR_GL_FRAMEBUFFER,
-                                        GR_GL_COLOR_ATTACHMENT0,
-                                        GR_GL_TEXTURE_2D, testRTTex, 0));
-    GrGLenum status;
-    GR_GL_CALL_RET(gl, status, CheckFramebufferStatus(GR_GL_FRAMEBUFFER));
-    GR_GL_CALL(gl, DeleteFramebuffers(1, &testFBO));
-    GR_GL_CALL(gl, DeleteTextures(1, &testRTTex));
-
-    return status == GR_GL_FRAMEBUFFER_COMPLETE;
-}
-
 GrGpuGL::GrGpuGL(const GrGLContext& ctx, GrContext* context)
     : GrGpu(context)
     , fGLContext(ctx) {
@@ -155,6 +123,8 @@ GrGpuGL::GrGpuGL(const GrGLContext& ctx, GrContext* context)
 
     fCaps.reset(SkRef(ctx.info().caps()));
 
+    fHWBoundTextures.reset(ctx.info().caps()->maxFragmentTextureUnits());
+
     fillInConfigRenderableTable();
 
 
@@ -183,9 +153,6 @@ GrGpuGL::GrGpuGL(const GrGLContext& ctx, GrContext* context)
     GrAssert(this->glCaps().maxVertexAttributes() >= GrDrawState::kMaxVertexAttribCnt);
 
     fLastSuccessfulStencilFmtIdx = 0;
-    if (false) { // avoid bit rot, suppress warning
-        fbo_test(this->glInterface(), 0, 0);
-    }
 }
 
 GrGpuGL::~GrGpuGL() {
@@ -473,7 +440,6 @@ GrTexture* GrGpuGL::onWrapBackendTexture(const GrBackendTextureDesc& desc) {
         return NULL;
     }
 
-    this->setSpareTextureUnit();
     return texture;
 }
 
@@ -527,7 +493,7 @@ bool GrGpuGL::onWriteTexturePixels(GrTexture* texture,
     }
     GrGLTexture* glTex = static_cast<GrGLTexture*>(texture);
 
-    this->setSpareTextureUnit();
+    this->setScratchTextureUnit();
     GL_CALL(BindTexture(GR_GL_TEXTURE_2D, glTex->textureID()));
     GrGLTexture::Desc desc;
     desc.fFlags = glTex->desc().fFlags;
@@ -952,7 +918,7 @@ GrTexture* GrGpuGL::onCreateTexture(const GrTextureDesc& desc,
         return return_null_texture();
     }
 
-    this->setSpareTextureUnit();
+    this->setScratchTextureUnit();
     GL_CALL(BindTexture(GR_GL_TEXTURE_2D, glTexDesc.fTextureID));
 
     // Some drivers like to know filter/wrap before seeing glTexImage2D. Some
@@ -2222,18 +2188,23 @@ bool GrGpuGL::configToGLFormats(GrPixelConfig config,
 }
 
 void GrGpuGL::setTextureUnit(int unit) {
-    GrAssert(unit >= 0 && unit < GrDrawState::kNumStages);
+    GrAssert(unit >= 0 && unit < fHWBoundTextures.count());
     if (fHWActiveTextureUnitIdx != unit) {

[jvanverth1, 2013/06/05 15:15:25]

Change to (unit != fHWActiveTextureUnitIdx) to match pattern below?

[bsalomon, 2013/06/05 15:45:10]

Done.

         GL_CALL(ActiveTexture(GR_GL_TEXTURE0 + unit));
         fHWActiveTextureUnitIdx = unit;
     }
 }
 
-void GrGpuGL::setSpareTextureUnit() {
-    if (fHWActiveTextureUnitIdx != (GR_GL_TEXTURE0 + SPARE_TEX_UNIT)) {
-        GL_CALL(ActiveTexture(GR_GL_TEXTURE0 + SPARE_TEX_UNIT));
-        fHWActiveTextureUnitIdx = SPARE_TEX_UNIT;
+void GrGpuGL::setScratchTextureUnit() {
+    // Bind the last texture unit since it is the least likely to be used by GrGLProgram.
+    int lastUnitIdx = this->glCaps().maxFragmentTextureUnits() - 1;
+    if (lastUnitIdx != fHWActiveTextureUnitIdx) {
+        GL_CALL(ActiveTexture(GR_GL_TEXTURE0 + lastUnitIdx));
+        fHWActiveTextureUnitIdx = lastUnitIdx;
     }
+    // clear out the this field so that if a program does use this unit it will rebind the correct

[jvanverth1, 2013/06/05 15:15:25]

I assume GrRefCnt will take care of any leaks here.

[bsalomon, 2013/06/05 15:45:10]

These are raw ptrs and don't own a ref. If this ref'ed a texture then it could
prevent that texture from ever being deleted. Instead, when the texture is
deleted it notifies GrGpuGL via notifyTextureDelete() and that function will
clear out any pointers to the texture being deleted.

Answering this caused me to notice that there were a couple other spots that
needed to be updated (loops on fHWBoundTextures that used kNumStages).

+    // texture.
+    fHWBoundTextures[lastUnitIdx] = NULL;
 }
 
 namespace {
@@ -2370,7 +2341,7 @@ bool GrGpuGL::onCopySurface(GrSurface* dst,
                                 srcRect.height(),
                                 src->origin());
 
-        this->setSpareTextureUnit();
+        this->setScratchTextureUnit();
         GL_CALL(BindTexture(GR_GL_TEXTURE_2D, dstTex->textureID()));
         GrGLint dstY;
         if (kBottomLeft_GrSurfaceOrigin == dst->origin()) {