From 630bf288de09e0fcf9734b297042cb751ec38376 Mon Sep 17 00:00:00 2001 From: Kenneth Graunke Date: Fri, 21 Mar 2014 15:58:02 -0700 Subject: [PATCH] mesa: Skip clearing color buffers when color writes are disabled. WebGL Aquarium in Chrome 24 actually hits this. v2: Move to core Mesa (wisely suggested by Ian); only consider components which actually exist. v3: Use _mesa_format_has_color_component to determine whether components actually exist, fixing alpha format handling. v4: Add a comment, as requested by Brian. No actual code changes. Signed-off-by: Kenneth Graunke Reviewed-by: Brian Paul Reviewed-by: Eric Anholt Reviewed-by: Ian Romanick Tested-by: Dylan Baker --- src/mesa/main/clear.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-) diff --git a/src/mesa/main/clear.c b/src/mesa/main/clear.c index 077c5fca3b7..9df1f5e098c 100644 --- a/src/mesa/main/clear.c +++ b/src/mesa/main/clear.c @@ -106,6 +106,31 @@ _mesa_ClearColorIuiEXT(GLuint r, GLuint g, GLuint b, GLuint a) } +/** + * Returns true if color writes are enabled for the given color attachment. + * + * Beyond checking ColorMask, this uses _mesa_format_has_color_component to + * ignore components that don't actually exist in the format (such as X in + * XRGB). + */ +static bool +color_buffer_writes_enabled(const struct gl_context *ctx, unsigned idx) +{ + struct gl_renderbuffer *rb = ctx->DrawBuffer->_ColorDrawBuffers[idx]; + GLuint c; + GLubyte colorMask = 0; + + if (rb) { + for (c = 0; c < 4; c++) { + if (_mesa_format_has_color_component(rb->Format, c)) + colorMask |= ctx->Color.ColorMask[idx][c]; + } + } + + return colorMask != 0; +} + + /** * Clear buffers. * @@ -181,7 +206,7 @@ _mesa_Clear( GLbitfield mask ) for (i = 0; i < ctx->DrawBuffer->_NumColorDrawBuffers; i++) { GLint buf = ctx->DrawBuffer->_ColorDrawBufferIndexes[i]; - if (buf >= 0) { + if (buf >= 0 && color_buffer_writes_enabled(ctx, i)) { bufferMask |= 1 << buf; } } -- 2.30.2