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-rw-r--r--mesalib/src/mesa/main/clear.c27
-rw-r--r--mesalib/src/mesa/main/formats.c29
-rw-r--r--mesalib/src/mesa/main/formats.h4
3 files changed, 59 insertions, 1 deletions
diff --git a/mesalib/src/mesa/main/clear.c b/mesalib/src/mesa/main/clear.c
index 077c5fca3..9df1f5e09 100644
--- a/mesalib/src/mesa/main/clear.c
+++ b/mesalib/src/mesa/main/clear.c
@@ -107,6 +107,31 @@ _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.
*
* \param mask bit-mask indicating the buffers to be cleared.
@@ -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;
}
}
diff --git a/mesalib/src/mesa/main/formats.c b/mesalib/src/mesa/main/formats.c
index e74625f23..fb2501c69 100644
--- a/mesalib/src/mesa/main/formats.c
+++ b/mesalib/src/mesa/main/formats.c
@@ -2207,6 +2207,35 @@ _mesa_format_num_components(mesa_format format)
/**
+ * Returns true if a color format has data stored in the R/G/B/A channels,
+ * given an index from 0 to 3.
+ */
+bool
+_mesa_format_has_color_component(mesa_format format, int component)
+{
+ const struct gl_format_info *info = _mesa_get_format_info(format);
+
+ assert(info->BaseFormat != GL_DEPTH_COMPONENT &&
+ info->BaseFormat != GL_DEPTH_STENCIL &&
+ info->BaseFormat != GL_STENCIL_INDEX);
+
+ switch (component) {
+ case 0:
+ return (info->RedBits + info->IntensityBits + info->LuminanceBits) > 0;
+ case 1:
+ return (info->GreenBits + info->IntensityBits + info->LuminanceBits) > 0;
+ case 2:
+ return (info->BlueBits + info->IntensityBits + info->LuminanceBits) > 0;
+ case 3:
+ return (info->AlphaBits + info->IntensityBits) > 0;
+ default:
+ assert(!"Invalid color component: must be 0..3");
+ return false;
+ }
+}
+
+
+/**
* Return number of bytes needed to store an image of the given size
* in the given format.
*/
diff --git a/mesalib/src/mesa/main/formats.h b/mesalib/src/mesa/main/formats.h
index 3079f0356..89bd0219e 100644
--- a/mesalib/src/mesa/main/formats.h
+++ b/mesalib/src/mesa/main/formats.h
@@ -34,6 +34,7 @@
#include <GL/gl.h>
+#include <stdbool.h>
#ifdef __cplusplus
@@ -474,6 +475,9 @@ _mesa_get_uncompressed_format(mesa_format format);
extern GLuint
_mesa_format_num_components(mesa_format format);
+extern bool
+_mesa_format_has_color_component(mesa_format format, int component);
+
GLboolean
_mesa_format_matches_format_and_type(mesa_format mesa_format,
GLenum format, GLenum type,