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, 8 insertions, 7 deletions

diff --git a/src/gallium/drivers/llvmpipe/lp_setup_tri.c b/src/gallium/drivers/llvmpipe/lp_setup_tri.c
index 53ab1f1f0c0..e22f14c9ca0 100644
--- a/src/gallium/drivers/llvmpipe/lp_setup_tri.c
+++ b/src/gallium/drivers/llvmpipe/lp_setup_tri.c
@@ -274,7 +274,7 @@ do_triangle_ccw(struct lp_setup_context *setup,
    struct u_rect bbox;
    unsigned tri_bytes;
    int nr_planes = 3;
-   unsigned scissor_index = 0;
+   unsigned viewport_index = 0;
    unsigned layer = 0;
 
    /* Area should always be positive here */
@@ -287,7 +287,7 @@ do_triangle_ccw(struct lp_setup_context *setup,
       nr_planes = 7;
       if (setup->viewport_index_slot > 0) {
          unsigned *udata = (unsigned*)v0[setup->viewport_index_slot];
-         scissor_index = lp_clamp_scissor_idx(*udata);
+         viewport_index = lp_clamp_viewport_idx(*udata);
       }
    }
    else {
@@ -323,7 +323,7 @@ do_triangle_ccw(struct lp_setup_context *setup,
       return TRUE;
    }
 
-   if (!u_rect_test_intersection(&setup->draw_regions[scissor_index], &bbox)) {
+   if (!u_rect_test_intersection(&setup->draw_regions[viewport_index], &bbox)) {
       if (0) debug_printf("offscreen\n");
       LP_COUNT(nr_culled_tris);
       return TRUE;
@@ -368,6 +368,7 @@ do_triangle_ccw(struct lp_setup_context *setup,
    tri->inputs.disable = FALSE;
    tri->inputs.opaque = setup->fs.current.variant->opaque;
    tri->inputs.layer = layer;
+   tri->inputs.viewport_index = viewport_index;
 
    if (0)
       lp_dump_setup_coef(&setup->setup.variant->key,
@@ -547,7 +548,7 @@ do_triangle_ccw(struct lp_setup_context *setup,
     * these planes elsewhere.
     */
    if (nr_planes == 7) {
-      const struct u_rect *scissor = &setup->scissors[scissor_index];
+      const struct u_rect *scissor = &setup->scissors[viewport_index];
 
       plane[3].dcdx = -1;
       plane[3].dcdy = 0;
@@ -570,7 +571,7 @@ do_triangle_ccw(struct lp_setup_context *setup,
       plane[6].eo = 0;
    }
 
-   return lp_setup_bin_triangle(setup, tri, &bbox, nr_planes, scissor_index);
+   return lp_setup_bin_triangle(setup, tri, &bbox, nr_planes, viewport_index);
 }
 
 /*
@@ -605,7 +606,7 @@ lp_setup_bin_triangle( struct lp_setup_context *setup,
                        struct lp_rast_triangle *tri,
                        const struct u_rect *bbox,
                        int nr_planes,
-                       unsigned scissor_index )
+                       unsigned viewport_index )
 {
    struct lp_scene *scene = setup->scene;
    struct u_rect trimmed_box = *bbox;   
@@ -628,7 +629,7 @@ lp_setup_bin_triangle( struct lp_setup_context *setup,
     * the rasterizer to also respect scissor, etc, just for the rare
     * cases where a small triangle extends beyond the scissor.
     */
-   u_rect_find_intersection(&setup->draw_regions[scissor_index],
+   u_rect_find_intersection(&setup->draw_regions[viewport_index],
                             &trimmed_box);
 
    /* Determine which tile(s) intersect the triangle's bounding box