Move dither from blend state to rasterizer state

Dither is technically not a part of blend state so it was removed from there as a first step towards exposing OES_draw_buffers_indexed (that defines independent blend state for each draw buffer).

Rasterizer state seems to be the closest (although also not accurate) place for it to keep code changes to a minimum. ANGLE's D3D11, Vulkan, and Metal renderers ignore dithering altogether.

Bug: angleproject:4394
Change-Id: Ib138624b9218851d18cd63e2033e8e8ac8ca71d9
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2050464
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>

src/libANGLE/State.cpp

@@ -898,7 +898,7 @@ void State::setScissorParams(GLint x, GLint y, GLsizei width, GLsizei height)
 
 void State::setDither(bool enabled)
 {
-    mBlend.dither = enabled;
+    mRasterizer.dither = enabled;
     mDirtyBits.set(DIRTY_BIT_DITHER_ENABLED);
 }
 
@@ -1906,7 +1906,7 @@ void State::getBooleanv(GLenum pname, GLboolean *params)
             *params = mBlend.blend;
             break;
         case GL_DITHER:
-            *params = mBlend.dither;
+            *params = mRasterizer.dither;
             break;
         case GL_TRANSFORM_FEEDBACK_ACTIVE:
             *params = getCurrentTransformFeedback()->isActive() ? GL_TRUE : GL_FALSE;

src/libANGLE/State.h

@@ -207,7 +207,7 @@ class State : angle::NonCopyable
     const Rectangle &getScissor() const { return mScissor; }
 
     // Dither state toggle & query
-    bool isDitherEnabled() const { return mBlend.dither; }
+    bool isDitherEnabled() const { return mRasterizer.dither; }
     void setDither(bool enabled);
 
     // Generic state toggle & query

src/libANGLE/angletypes.cpp

@@ -27,6 +27,12 @@ RasterizerState::RasterizerState()
     polygonOffsetUnits  = 0.0f;
     pointDrawMode       = false;
     multiSample         = false;
+    dither              = true;
+}
+
+RasterizerState::RasterizerState(const RasterizerState &other)
+{
+    memcpy(this, &other, sizeof(RasterizerState));
 }
 
 bool operator==(const RasterizerState &a, const RasterizerState &b)
@@ -51,7 +57,6 @@ BlendState::BlendState()
     blendEquationRGB      = GL_FUNC_ADD;
     blendEquationAlpha    = GL_FUNC_ADD;
     sampleAlphaToCoverage = false;
-    dither                = true;
     colorMaskRed          = true;
     colorMaskGreen        = true;
     colorMaskBlue         = true;

src/libANGLE/angletypes.h

@@ -127,6 +127,7 @@ struct RasterizerState final
 {
     // This will zero-initialize the struct, including padding.
     RasterizerState();
+    RasterizerState(const RasterizerState &other);
 
     bool cullFace;
     CullFaceMode cullMode;
@@ -140,6 +141,8 @@ struct RasterizerState final
     bool multiSample;
 
     bool rasterizerDiscard;
+
+    bool dither;
 };
 
 bool operator==(const RasterizerState &a, const RasterizerState &b);
@@ -167,8 +170,6 @@ struct BlendState final
     bool colorMaskAlpha;
 
     bool sampleAlphaToCoverage;
-
-    bool dither;
 };
 
 bool operator==(const BlendState &a, const BlendState &b);

src/libANGLE/renderer/d3d/d3d11/Clear11.cpp

@@ -295,7 +295,6 @@ angle::Result Clear11::ensureResourcesInitialized(const gl::Context *context)
     mBlendStateKey.blendState.blendEquationRGB      = GL_FUNC_ADD;
     mBlendStateKey.blendState.blendEquationAlpha    = GL_FUNC_ADD;
     mBlendStateKey.blendState.sampleAlphaToCoverage = false;
-    mBlendStateKey.blendState.dither                = true;
 
     mResourcesInitialized = true;
     return angle::Result::Continue;

src/libANGLE/renderer/d3d/d3d11/StateManager11.cpp

@@ -711,7 +711,6 @@ StateManager11::StateManager11(Renderer11 *renderer)
     mCurBlendState.colorMaskGreen        = true;
     mCurBlendState.colorMaskAlpha        = true;
     mCurBlendState.sampleAlphaToCoverage = false;
-    mCurBlendState.dither                = false;
 
     mCurDepthStencilState.depthTest                = false;
     mCurDepthStencilState.depthFunc                = GL_LESS;
@@ -738,6 +737,7 @@ StateManager11::StateManager11(Renderer11 *renderer)
     mCurRasterState.polygonOffsetUnits  = 0.0f;
     mCurRasterState.pointDrawMode       = false;
     mCurRasterState.multiSample         = false;
+    mCurRasterState.dither              = false;
 
     // Start with all internal dirty bits set except DIRTY_BIT_COMPUTE_SRVUAV_STATE and
     // DIRTY_BIT_GRAPHICS_SRVUAV_STATE.
@@ -993,9 +993,9 @@ void StateManager11::syncState(const gl::Context *context, const gl::State::Dirt
                 }
                 break;
             case gl::State::DIRTY_BIT_DITHER_ENABLED:
-                if (state.getBlendState().dither != mCurBlendState.dither)
+                if (state.getRasterizerState().dither != mCurRasterState.dither)
                 {
-                    mInternalDirtyBits.set(DIRTY_BIT_BLEND_STATE);
+                    mInternalDirtyBits.set(DIRTY_BIT_RASTERIZER_STATE);
                 }
                 break;
             case gl::State::DIRTY_BIT_COLOR_MASK:

src/libANGLE/renderer/d3d/d3d9/StateManager9.cpp

@@ -201,7 +201,7 @@ void StateManager9::syncState(const gl::State &state, const gl::State::DirtyBits
                 break;
             }
             case gl::State::DIRTY_BIT_DITHER_ENABLED:
-                if (state.getBlendState().dither != mCurBlendState.dither)
+                if (state.getRasterizerState().dither != mCurRasterState.dither)
                 {
                     mDirtyBits.set(DIRTY_BIT_DITHER);
                 }
@@ -361,7 +361,7 @@ void StateManager9::setBlendDepthRasterStates(const gl::State &glState, unsigned
                              blendState.colorMaskGreen, blendState.colorMaskAlpha);
                 break;
             case DIRTY_BIT_DITHER:
-                setDither(blendState.dither);
+                setDither(rasterState.dither);
                 break;
             case DIRTY_BIT_CULL_MODE:
                 setCullMode(rasterState.cullFace, rasterState.cullMode, rasterState.frontFace);
@@ -763,7 +763,7 @@ void StateManager9::setBlendEnabled(bool enabled)
 void StateManager9::setDither(bool dither)
 {
     mRenderer9->getDevice()->SetRenderState(D3DRS_DITHERENABLE, dither ? TRUE : FALSE);
-    mCurBlendState.dither = dither;
+    mCurRasterState.dither = dither;
 }
 
 // TODO(dianx) one bit for color mask