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authorRobert Ellison <papillo@i965-laptop.(none)>2009-02-12 13:47:36 -0700
committerRobert Ellison <papillo@i965-laptop.(none)>2009-02-12 13:47:36 -0700
commit5de5ab428cf5516d91daa3f193a76b0d87853f55 (patch)
tree4212b37503d12c3b8d3adc52ba3ab0e94f090faa /src/mesa/main/buffers.c
parentf1a59a6dd7b7b0523db191d82b3af1a841c6475d (diff)
glDrawBuffers(n==0) is valid
According to the GL spec, calling glDrawBuffers() with n == 0 is a valid operation (and essentially prevents drawing to any buffers). But _msa_DrawBuffersARB() was producing a GL_INVALID_VALUE error in this case. This fix adjusts the error check, and makes a small change to the ctx->Driver.DrawBuffer() call below to ensure that, if n == 0, Driver.DrawBuffer() is called with GL_NONE and that buffers[0] is *not* referenced in this case (since we don't know whether it is valid). Internal identifier: 365833
Diffstat (limited to 'src/mesa/main/buffers.c')
-rw-r--r--src/mesa/main/buffers.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/src/mesa/main/buffers.c b/src/mesa/main/buffers.c
index 818d068a12..85db3868c4 100644
--- a/src/mesa/main/buffers.c
+++ b/src/mesa/main/buffers.c
@@ -290,7 +290,10 @@ _mesa_DrawBuffersARB(GLsizei n, const GLenum *buffers)
GET_CURRENT_CONTEXT(ctx);
ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
- if (n < 1 || n > (GLsizei) ctx->Const.MaxDrawBuffers) {
+ /* Turns out n==0 is a valid input that should not produce an error.
+ * The remaining code below correctly handles the n==0 case.
+ */
+ if (n < 0 || n > (GLsizei) ctx->Const.MaxDrawBuffers) {
_mesa_error(ctx, GL_INVALID_VALUE, "glDrawBuffersARB(n)");
return;
}
@@ -332,12 +335,14 @@ _mesa_DrawBuffersARB(GLsizei n, const GLenum *buffers)
_mesa_drawbuffers(ctx, n, buffers, destMask);
/*
- * Call device driver function.
+ * Call device driver function. Note that n can be equal to 0,
+ * in which case we don't want to reference buffers[0], which
+ * may not be valid.
*/
if (ctx->Driver.DrawBuffers)
ctx->Driver.DrawBuffers(ctx, n, buffers);
else if (ctx->Driver.DrawBuffer)
- ctx->Driver.DrawBuffer(ctx, buffers[0]);
+ ctx->Driver.DrawBuffer(ctx, n>0? buffers[0]:GL_NONE);
}