llvmpipe: clamp fragment shader depth write to the current viewport depth range.

With this patch, generate_fs_loop will clamp any fragment shader depth writes
to the viewport's min and max depth values. Viewport selection is determined
by the geometry shader output for the viewport array index. If no index is
specified, then the default viewport index is zero. Semantics for this path
can be found in draw_clamp_viewport_idx and lp_clamp_viewport_idx.

lp_jit_viewport was created to store viewport information visible to JIT code,
and is validated when the LP_NEW_VIEWPORT dirty flag is set.

lp_rast_shader_inputs is responsible for passing the viewport_index through
the rasterizer stage to fragment stage (via lp_jit_thread_data).

Reviewed-by: Roland Scheidegger <[email protected]>
Reviewed-by: José Fonseca <[email protected]>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/gallium/drivers/llvmpipe/lp_rast.h b/src/gallium/drivers/llvmpipe/lp_rast.h
index b81d94f50f0..e2a9ec20892 100644
--- a/src/gallium/drivers/llvmpipe/lp_rast.h
+++ b/src/gallium/drivers/llvmpipe/lp_rast.h
@@ -102,7 +102,7 @@ struct lp_rast_shader_inputs {
    unsigned pad0:29;            /* wasted space */
    unsigned stride;             /* how much to advance data between a0, dadx, dady */
    unsigned layer;              /* the layer to render to (from gs, already clamped) */
-   unsigned pad2;               /* wasted space */
+   unsigned viewport_index;     /* the active viewport index (from gs, already clamped) */
    /* followed by a0, dadx, dady and planes[] */
 };