llvmpipe: add support for layered rendering

Mostly just make sure the layer parameter gets passed through to the right
places (and get clamped, can do this at setup time), fix up clears to
clear all layers and disable opaque optimization. Luckily don't need to
touch the jitted code.
(Clears invoked via pipe's clear_render_target method will not work however
since the pipe_util_clear function used for it doesn't handle clearing
multiple layers yet.)

v2: per Brian's suggestion, prettify var initialization and add some comments,
add assertion for impossible layer specification for surface.

Reviewed-by: Brian Paul <[email protected]>
Reviewed-by: Jose Fonseca <[email protected]>

1 files changed, 3 insertions, 0 deletions

diff --git a/src/gallium/drivers/llvmpipe/lp_context.h b/src/gallium/drivers/llvmpipe/lp_context.h
index 54f38303ae5..abfe852bae5 100644
--- a/src/gallium/drivers/llvmpipe/lp_context.h
+++ b/src/gallium/drivers/llvmpipe/lp_context.h
@@ -119,6 +119,9 @@ struct llvmpipe_context {
    /** Which vertex shader output slot contains viewport index */
    int viewport_index_slot;
 
+   /** Which geometry shader output slot contains layer */
+   int layer_slot;
+
    /**< minimum resolvable depth value, for polygon offset */   
    double mrd;