llvmpipe: implement scissor testing

The scissor test is implemented as another per-quad operation in
the JIT code.  The four scissor box params are passed via the
lp_jit_context.  In the JIT code we compare the quad's x/y coords
against the clip bounds and create a new in/out mask that's AND'd
with the main quad mask.

Note: we should also do scissor testing in the triangle setup code
to improve efficiency.  That's not done yet.

1 files changed, 17 insertions, 2 deletions

diff --git a/src/gallium/drivers/llvmpipe/lp_jit.h b/src/gallium/drivers/llvmpipe/lp_jit.h
index 3b316914b0..9cbe1bd3b1 100644
--- a/src/gallium/drivers/llvmpipe/lp_jit.h
+++ b/src/gallium/drivers/llvmpipe/lp_jit.h
@@ -79,6 +79,9 @@ struct lp_jit_context
 
    float alpha_ref_value;
 
+   /** floats, not ints */
+   float scissor_xmin, scissor_ymin, scissor_xmax, scissor_ymax;
+
    /* FIXME: store (also?) in floats */
    uint8_t *blend_color;
 
@@ -92,10 +95,22 @@ struct lp_jit_context
 #define lp_jit_context_alpha_ref_value(_builder, _ptr) \
    lp_build_struct_get(_builder, _ptr, 1, "alpha_ref_value")
 
+#define lp_jit_context_scissor_xmin_value(_builder, _ptr) \
+   lp_build_struct_get(_builder, _ptr, 2, "scissor_xmin")
+
+#define lp_jit_context_scissor_ymin_value(_builder, _ptr) \
+   lp_build_struct_get(_builder, _ptr, 3, "scissor_ymin")
+
+#define lp_jit_context_scissor_xmax_value(_builder, _ptr) \
+   lp_build_struct_get(_builder, _ptr, 4, "scissor_xmax")
+
+#define lp_jit_context_scissor_ymax_value(_builder, _ptr) \
+   lp_build_struct_get(_builder, _ptr, 5, "scissor_ymax")
+
 #define lp_jit_context_blend_color(_builder, _ptr) \
-   lp_build_struct_get(_builder, _ptr, 2, "blend_color")
+   lp_build_struct_get(_builder, _ptr, 6, "blend_color")
 
-#define LP_JIT_CONTEXT_TEXTURES_INDEX 3
+#define LP_JIT_CONTEXT_TEXTURES_INDEX 7
 
 #define lp_jit_context_textures(_builder, _ptr) \
    lp_build_struct_get_ptr(_builder, _ptr, LP_JIT_CONTEXT_TEXTURES_INDEX, "textures")