[Mesa-dev] [PATCH 1/2] st/mesa: Handle disabled draw buffers in st_Clear().

[Henri Verbeet]

This fixes piglit arb_draw_buffers-rt0_none on AMD CEDAR. No piglit
regressions on the same hardware.

Signed-off-by: Henri Verbeet <hverbeet at gmail.com>
---
 src/mesa/state_tracker/st_cb_clear.c |   14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/mesa/state_tracker/st_cb_clear.c b/src/mesa/state_tracker/st_cb_clear.c
index 887e58b..e7345a2 100644
--- a/src/mesa/state_tracker/st_cb_clear.c
+++ b/src/mesa/state_tracker/st_cb_clear.c
@@ -430,14 +430,20 @@ st_Clear(struct gl_context *ctx, GLbitfield mask)
    st_validate_state( st );
 
    if (mask & BUFFER_BITS_COLOR) {
+      unsigned int color_idx = ~0u;
+
       for (i = 0; i < ctx->DrawBuffer->_NumColorDrawBuffers; i++) {
-         GLuint b = ctx->DrawBuffer->_ColorDrawBufferIndexes[i];
+         gl_buffer_index b = ctx->DrawBuffer->_ColorDrawBufferIndexes[i];
+
+         if (b == -1)
+            continue;
 
+         ++color_idx;
          if (mask & (1 << b)) {
             struct gl_renderbuffer *rb
                = ctx->DrawBuffer->Attachment[b].Renderbuffer;
             struct st_renderbuffer *strb = st_renderbuffer(rb);
-            int colormask_index = ctx->Extensions.EXT_draw_buffers2 ? i : 0;
+            int colormask_index = ctx->Extensions.EXT_draw_buffers2 ? color_idx : 0;
 
             if (!strb || !strb->surface)
                continue;
@@ -447,9 +453,9 @@ st_Clear(struct gl_context *ctx, GLbitfield mask)
 
             if (is_scissor_enabled(ctx, rb) ||
                 is_color_masked(ctx, colormask_index))
-               quad_buffers |= PIPE_CLEAR_COLOR0 << i;
+               quad_buffers |= PIPE_CLEAR_COLOR0 << color_idx;
             else
-               clear_buffers |= PIPE_CLEAR_COLOR0 << i;
+               clear_buffers |= PIPE_CLEAR_COLOR0 << color_idx;
          }
       }
    }
-- 
1.7.10.4