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, 16 insertions, 5 deletions

diff --git a/src/gallium/drivers/llvmpipe/lp_jit.c b/src/gallium/drivers/llvmpipe/lp_jit.c
index 4ef0783f3e..429cb973c2 100644
--- a/src/gallium/drivers/llvmpipe/lp_jit.c
+++ b/src/gallium/drivers/llvmpipe/lp_jit.c
@@ -79,13 +79,16 @@ lp_jit_init_globals(struct llvmpipe_screen *screen)
 
    /* struct lp_jit_context */
    {
-      LLVMTypeRef elem_types[4];
+      LLVMTypeRef elem_types[8];
       LLVMTypeRef context_type;
 
       elem_types[0] = LLVMPointerType(LLVMFloatType(), 0); /* constants */
-      elem_types[1] = LLVMFloatType();                     /* alpha_ref_value */
-      elem_types[2] = LLVMPointerType(LLVMInt8Type(), 0);  /* blend_color */
-      elem_types[3] = LLVMArrayType(texture_type, PIPE_MAX_SAMPLERS); /* textures */
+      elem_types[1] = LLVMFloatType();                     /* alpha_ref_value */      elem_types[2] = LLVMFloatType();                     /* scissor_xmin */
+      elem_types[3] = LLVMFloatType();                     /* scissor_ymin */
+      elem_types[4] = LLVMFloatType();                     /* scissor_xmax */
+      elem_types[5] = LLVMFloatType();                     /* scissor_ymax */
+      elem_types[6] = LLVMPointerType(LLVMInt8Type(), 0);  /* blend_color */
+      elem_types[7] = LLVMArrayType(texture_type, PIPE_MAX_SAMPLERS); /* textures */
 
       context_type = LLVMStructType(elem_types, Elements(elem_types), 0);
 
@@ -93,8 +96,16 @@ lp_jit_init_globals(struct llvmpipe_screen *screen)
                              screen->target, context_type, 0);
       LP_CHECK_MEMBER_OFFSET(struct lp_jit_context, alpha_ref_value,
                              screen->target, context_type, 1);
-      LP_CHECK_MEMBER_OFFSET(struct lp_jit_context, blend_color,
+      LP_CHECK_MEMBER_OFFSET(struct lp_jit_context, scissor_xmin,
                              screen->target, context_type, 2);
+      LP_CHECK_MEMBER_OFFSET(struct lp_jit_context, scissor_ymin,
+                             screen->target, context_type, 3);
+      LP_CHECK_MEMBER_OFFSET(struct lp_jit_context, scissor_xmax,
+                             screen->target, context_type, 4);
+      LP_CHECK_MEMBER_OFFSET(struct lp_jit_context, scissor_ymax,
+                             screen->target, context_type, 5);
+      LP_CHECK_MEMBER_OFFSET(struct lp_jit_context, blend_color,
+                             screen->target, context_type, 6);
       LP_CHECK_MEMBER_OFFSET(struct lp_jit_context, textures,
                              screen->target, context_type,
                              LP_JIT_CONTEXT_TEXTURES_INDEX);