Fix clearIfComposited for indexed color write masks

https://bugs.webkit.org/show_bug.cgi?id=241511

Patch by Alexey Knyazev <3479527+lexaknyazev@users.noreply.github.com> on 2022-06-13
Reviewed by Kimmo Kinnunen.

Implicit clears must correctly restore color write mask state.

* Source/WebCore/html/canvas/OESDrawBuffersIndexed.cpp:
(WebCore::OESDrawBuffersIndexed::colorMaskiOES):
* Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:
(WebCore::WebGLRenderingContextBase::clearIfComposited):
(WebCore::WebGLRenderingContextBase::restoreStateAfterClear):
* Source/WebCore/html/canvas/WebGLRenderingContextBase.h:

Canonical link: https://commits.webkit.org/251490@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@295485 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/WebCore/html/canvas/OESDrawBuffersIndexed.cpp

@@ -105,6 +105,14 @@ void OESDrawBuffersIndexed::colorMaskiOES(GCGLuint buf, GCGLboolean red, GCGLboo
     if (!m_context || m_context->isContextLost())
         return;
 
+    // Used in WebGLRenderingContextBase::clearIfComposited
+    if (!buf) {
+        m_context->m_colorMask[0] = red;
+        m_context->m_colorMask[1] = green;
+        m_context->m_colorMask[2] = blue;
+        m_context->m_colorMask[3] = alpha;
+    }
+
     m_context->graphicsContextGL()->colorMaskiOES(buf, red, green, blue, alpha);
 }
 

Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp

@@ -1361,7 +1361,10 @@ bool WebGLRenderingContextBase::clearIfComposited(WebGLRenderingContextBase::Cle
                               m_colorMask[3] ? m_clearColor[3] : 0);
     } else
         m_context->clearColor(0, 0, 0, 0);
-    m_context->colorMask(true, true, true, true);
+    if (m_oesDrawBuffersIndexed)
+        m_context->colorMaskiOES(0, true, true, true, true);
+    else
+        m_context->colorMask(true, true, true, true);
     GCGLbitfield clearMask = GraphicsContextGL::COLOR_BUFFER_BIT;
     if (contextAttributes.depth) {
         if (!combinedClear || !m_depthMask || !(mask & GraphicsContextGL::DEPTH_BUFFER_BIT))
@@ -1405,8 +1408,10 @@ void WebGLRenderingContextBase::restoreStateAfterClear()
         m_context->enable(GraphicsContextGL::SCISSOR_TEST);
     m_context->clearColor(m_clearColor[0], m_clearColor[1],
                           m_clearColor[2], m_clearColor[3]);
-    m_context->colorMask(m_colorMask[0], m_colorMask[1],
-                         m_colorMask[2], m_colorMask[3]);
+    if (m_oesDrawBuffersIndexed)
+        m_context->colorMaskiOES(0, m_colorMask[0], m_colorMask[1], m_colorMask[2], m_colorMask[3]);
+    else
+        m_context->colorMask(m_colorMask[0], m_colorMask[1], m_colorMask[2], m_colorMask[3]);
     m_context->clearDepth(m_clearDepth);
     m_context->clearStencil(m_clearStencil);
     m_context->stencilMaskSeparate(GraphicsContextGL::FRONT, m_stencilMask);

Source/WebCore/html/canvas/WebGLRenderingContextBase.h

@@ -446,6 +446,7 @@ class WebGLRenderingContextBase : public GraphicsContextGL::Client, public GPUBa
 
     friend class EXTTextureCompressionBPTC;
     friend class EXTTextureCompressionRGTC;
+    friend class OESDrawBuffersIndexed;
     friend class OESVertexArrayObject;
     friend class WebGLCompressedTextureASTC;
     friend class WebGLCompressedTextureATC;