[Mesa-dev] [PATCH] msaa: Make meta-ops save and restore state of GL_MULTISAMPLE.

[Paul Berry]

The meta-ops _mesa_meta_Clear() and _mesa_meta_glsl_Clear() need to
ignore the state of GL_SAMPLE_ALPHA_TO_COVERAGE,
GL_SAMPLE_ALPHA_TO_ONE, GL_SAMPLE_COVERAGE, GL_SAMPLE_COVERAGE_VALUE,
and GL_SAMPLE_COVERAGE_INVERT when clearing multisampled buffers.  The
easiest way to accomplish this is to disable GL_MULTISAMPLE during the
clear meta-ops.

Note: this patch also causes GL_MULTISAMPLE to be disabled during
_mesa_meta_GenerateMipmap() and _mesa_meta_GetTexImage() (since those
two meta-ops use MESA_META_ALL).  Arguably this isn't strictly
necessary, since those meta-ops use their own non-MSAA fbo's, but it
shouldn't do any harm.

Fixes Piglit tests "EXT_framebuffer_multisample/clear {2,4}
{color,stencil}" on i965.
---
 src/mesa/drivers/common/meta.c |   17 ++++++++++++++++-
 src/mesa/drivers/common/meta.h |    1 +
 2 files changed, 17 insertions(+), 1 deletions(-)

diff --git a/src/mesa/drivers/common/meta.c b/src/mesa/drivers/common/meta.c
index be7141a..5e9d795 100644
--- a/src/mesa/drivers/common/meta.c
+++ b/src/mesa/drivers/common/meta.c
@@ -181,6 +181,9 @@ struct save_state
    struct gl_feedback Feedback;
 #endif
 
+   /** MESA_META_MULTISAMPLE */
+   GLboolean MultisampleEnabled;
+
    /** Miscellaneous (always disabled) */
    GLboolean Lighting;
    GLboolean RasterDiscard;
@@ -733,6 +736,12 @@ _mesa_meta_begin(struct gl_context *ctx, GLbitfield state)
    }
 #endif
 
+   if (state & MESA_META_MULTISAMPLE) {
+      save->MultisampleEnabled = ctx->Multisample.Enabled;
+      if (ctx->Multisample.Enabled)
+         _mesa_set_enable(ctx, GL_MULTISAMPLE, GL_FALSE);
+   }
+
    /* misc */
    {
       save->Lighting = ctx->Light.Enabled;
@@ -1018,6 +1027,11 @@ _mesa_meta_end(struct gl_context *ctx)
    }
 #endif
 
+   if (state & MESA_META_MULTISAMPLE) {
+      if (ctx->Multisample.Enabled != save->MultisampleEnabled)
+         _mesa_set_enable(ctx, GL_MULTISAMPLE, save->MultisampleEnabled);
+   }
+
    /* misc */
    if (save->Lighting) {
       _mesa_set_enable(ctx, GL_LIGHTING, GL_TRUE);
@@ -1902,7 +1916,8 @@ _mesa_meta_glsl_Clear(struct gl_context *ctx, GLbitfield buffers)
 	       MESA_META_VERTEX |
 	       MESA_META_VIEWPORT |
 	       MESA_META_CLIP |
-	       MESA_META_CLAMP_FRAGMENT_COLOR);
+	       MESA_META_CLAMP_FRAGMENT_COLOR |
+               MESA_META_MULTISAMPLE);
 
    if (!(buffers & BUFFER_BITS_COLOR)) {
       /* We'll use colormask to disable color writes.  Otherwise,
diff --git a/src/mesa/drivers/common/meta.h b/src/mesa/drivers/common/meta.h
index 7a80b1d..d8dfb56 100644
--- a/src/mesa/drivers/common/meta.h
+++ b/src/mesa/drivers/common/meta.h
@@ -55,6 +55,7 @@
 #define MESA_META_CONDITIONAL_RENDER    0x20000
 #define MESA_META_CLIP                  0x40000
 #define MESA_META_SELECT_FEEDBACK       0x80000
+#define MESA_META_MULTISAMPLE          0x100000
 /**\}*/
 
 extern void
-- 
1.7.7.6