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authorPaul Berry <stereotype441@gmail.com>2012-07-26 18:01:28 -0700
committerPaul Berry <stereotype441@gmail.com>2012-08-01 12:45:15 -0700
commit97fc89c6cbaa3b5ef7f678d2dc2c7d5bbba05315 (patch)
tree357d9e09d8b56536aad4bdc80e0779e4f3df41a3 /src/mesa/drivers/dri/i965/gen6_multisample_state.c
parentd5c918f6adb2f7f72a759607c8f76e7616656c13 (diff)
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i965/msaa: Treat GL_SAMPLES=1 as equivalent to GL_SAMPLES=0.
EXT_framebuffer_multisample is a required subpart of ARB_framebuffer_object, which means that we must support it even on platforms that don't support MSAA. Fortunately EXT_framebuffer_multisample allows for this by allowing GL_MAX_SAMPLES to be set to 1. This leads to a tricky quirk in the GL spec: since GlRenderbufferStorageMultisamples() accepts any value for its "samples" parameter up to and including GL_MAX_SAMPLES, that means that on platforms that don't support MSAA, GL_SAMPLES is allowed to be set to either 0 or 1. On platforms that do support MSAA, GL_SAMPLES=1 is not used; 0 means no MSAA, and 2 or higher means MSAA. In other words, GL_SAMPLES needs to be interpreted as follows: =0 no MSAA (possible on all platforms) =1 no MSAA (only possible on platforms where MSAA unsupported) >1 MSAA (only possible on platforms where MSAA supported) This patch modifies all MSAA-related code to choose between multisampling and single-sampling based on the condition (GL_SAMPLES > 1) instead of (GL_SAMPLES > 0) so that GL_SAMPLES=1 will be treated as "no MSAA". Note that since GL_SAMPLES=1 implies GL_SAMPLE_BUFFERS=1, we can no longer use GL_SAMPLE_BUFFERS to distinguish between MSAA and non-MSAA rendering. Reviewed-by: Jordan Justen <jordan.l.justen@intel.com> Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Diffstat (limited to 'src/mesa/drivers/dri/i965/gen6_multisample_state.c')
-rw-r--r--src/mesa/drivers/dri/i965/gen6_multisample_state.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/src/mesa/drivers/dri/i965/gen6_multisample_state.c b/src/mesa/drivers/dri/i965/gen6_multisample_state.c
index 68d28dd..64ac292 100644
--- a/src/mesa/drivers/dri/i965/gen6_multisample_state.c
+++ b/src/mesa/drivers/dri/i965/gen6_multisample_state.c
@@ -42,6 +42,7 @@ gen6_emit_3dstate_multisample(struct brw_context *brw,
switch (num_samples) {
case 0:
+ case 1:
number_of_multisamples = MS_NUMSAMPLES_1;
break;
case 4:
@@ -121,7 +122,7 @@ gen6_emit_3dstate_sample_mask(struct brw_context *brw,
BEGIN_BATCH(2);
OUT_BATCH(_3DSTATE_SAMPLE_MASK << 16 | (2 - 2));
- if (num_samples > 0) {
+ if (num_samples > 1) {
int coverage_int = (int) (num_samples * coverage + 0.5);
uint32_t coverage_bits = (1 << coverage_int) - 1;
if (coverage_invert)