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glDrawBuffers(n==0) is valid

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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
This commit is contained in:
Robert Ellison
2009-02-12 13:47:36 -07:00
parent f1a59a6dd7
commit 5de5ab428c
1 changed files with 8 additions and 3 deletions
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src/mesa/main/buffers.c
+8 -3
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@@ -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);
}