i965: support for two-sided lighting on Sandybridge

VS places color attributes together so that SF unit can fetch the right
attribute according to object orientation. This fixes light issue in
mesa demo geartrain, projtex.

1 files changed, 29 insertions, 3 deletions

diff --git a/src/mesa/drivers/dri/i965/gen6_sf_state.c b/src/mesa/drivers/dri/i965/gen6_sf_state.c
index 4cd2d69583..45c148baed 100644
--- a/src/mesa/drivers/dri/i965/gen6_sf_state.c
+++ b/src/mesa/drivers/dri/i965/gen6_sf_state.c
@@ -33,9 +33,10 @@
 #include "intel_batchbuffer.h"
 
 static uint32_t
-get_attr_override(struct brw_context *brw, int fs_attr)
+get_attr_override(struct brw_context *brw, int fs_attr, int two_side_color)
 {
    int attr_index = 0, i, vs_attr;
+   int bfc = 0;
 
    if (fs_attr <= FRAG_ATTRIB_TEX7)
       vs_attr = fs_attr;
@@ -57,6 +58,30 @@ get_attr_override(struct brw_context *brw, int fs_attr)
 	 attr_index++;
    }
 
+   assert(attr_index < 32);
+
+   if (two_side_color) {
+       if ((brw->vs.prog_data->outputs_written & BITFIELD64_BIT(VERT_RESULT_COL1)) &&
+           (brw->vs.prog_data->outputs_written & BITFIELD64_BIT(VERT_RESULT_BFC1))) {
+           assert(brw->vs.prog_data->outputs_written & BITFIELD64_BIT(VERT_RESULT_COL0));
+           assert(brw->vs.prog_data->outputs_written & BITFIELD64_BIT(VERT_RESULT_BFC0));
+           bfc = 2;
+       } else if ((brw->vs.prog_data->outputs_written & BITFIELD64_BIT(VERT_RESULT_COL0)) &&
+                (brw->vs.prog_data->outputs_written & BITFIELD64_BIT(VERT_RESULT_BFC0)))
+           bfc = 1;
+   }
+
+   if (bfc && (fs_attr <= FRAG_ATTRIB_TEX7 && fs_attr > FRAG_ATTRIB_WPOS)) {
+       if (fs_attr == FRAG_ATTRIB_COL0)
+           attr_index |= (ATTRIBUTE_SWIZZLE_INPUTATTR_FACING << ATTRIBUTE_SWIZZLE_SHIFT);
+       else if (fs_attr == FRAG_ATTRIB_COL1 && bfc == 2) {
+           attr_index++;
+           attr_index |= (ATTRIBUTE_SWIZZLE_INPUTATTR_FACING << ATTRIBUTE_SWIZZLE_SHIFT);
+       } else {
+           attr_index += bfc;
+       }
+   }
+
    return attr_index;
 }
 
@@ -75,6 +100,7 @@ upload_sf_state(struct brw_context *brw)
    GLboolean render_to_fbo = brw->intel.ctx.DrawBuffer->Name != 0;
    int attr = 0;
    int urb_start;
+   int two_side_color = (ctx->Light.Enabled && ctx->Light.Model.TwoSide);
 
    /* _NEW_TRANSFORM */
    if (ctx->Transform.ClipPlanesEnabled)
@@ -224,7 +250,7 @@ upload_sf_state(struct brw_context *brw)
 
       for (; attr < 64; attr++) {
 	 if (brw->fragment_program->Base.InputsRead & BITFIELD64_BIT(attr)) {
-	    attr_overrides |= get_attr_override(brw, attr);
+	    attr_overrides |= get_attr_override(brw, attr, two_side_color);
 	    attr++;
 	    break;
 	 }
@@ -232,7 +258,7 @@ upload_sf_state(struct brw_context *brw)
 
       for (; attr < 64; attr++) {
 	 if (brw->fragment_program->Base.InputsRead & BITFIELD64_BIT(attr)) {
-	    attr_overrides |= get_attr_override(brw, attr) << 16;
+	    attr_overrides |= get_attr_override(brw, attr, two_side_color) << 16;
 	    attr++;
 	    break;
 	 }