llvmpipe: pass mask into fragment shader

Move this code back out to C for now, will generate separately.

Shader now takes a mask parameter instead of C0/C1/C2/etc.

Shader does not currently use that parameter and rasterizes whole
pixel stamps always.

1 files changed, 379 insertions, 230 deletions

diff --git a/src/gallium/drivers/llvmpipe/lp_setup_tri.c b/src/gallium/drivers/llvmpipe/lp_setup_tri.c
index 4e2e17f77b..036b5497fa 100644
--- a/src/gallium/drivers/llvmpipe/lp_setup_tri.c
+++ b/src/gallium/drivers/llvmpipe/lp_setup_tri.c
@@ -38,12 +38,78 @@
 
 #define NUM_CHANNELS 4
 
+struct tri_info {
+
+   float pixel_offset;
+
+   /* fixed point vertex coordinates */
+   int x[3];
+   int y[3];
+
+   /* float x,y deltas - all from the original coordinates
+    */
+   float dy01, dy20;
+   float dx01, dx20;
+   float oneoverarea;
+
+   const float (*v0)[4];
+   const float (*v1)[4];
+   const float (*v2)[4];
+
+   boolean frontfacing;
+};
+
+
+
+static const int step_scissor_minx[16] = {
+   0, 1, 0, 1,
+   2, 3, 2, 3,
+   0, 1, 0, 1,
+   2, 3, 2, 3
+};
+
+static const int step_scissor_maxx[16] = {
+    0, -1,  0, -1,
+   -2, -3, -2, -3,
+    0, -1,  0, -1,
+   -2, -3, -2, -3
+};
+
+static const int step_scissor_miny[16] = {
+   0, 0, 1, 1,
+   0, 0, 1, 1,
+   2, 2, 3, 3,
+   2, 2, 3, 3
+};
+
+static const int step_scissor_maxy[16] = {
+    0,  0, -1, -1,
+    0,  0, -1, -1,
+   -2, -2, -3, -3,
+   -2, -2, -3, -3
+};
+
+
+
+   
+static INLINE int
+subpixel_snap(float a)
+{
+   return util_iround(FIXED_ONE * a);
+}
+
+static INLINE float
+fixed_to_float(int a)
+{
+   return a * (1.0 / FIXED_ONE);
+}
+
+
 
 /**
  * Compute a0 for a constant-valued coefficient (GL_FLAT shading).
  */
-static void constant_coef( struct lp_setup_context *setup,
-                           struct lp_rast_triangle *tri,
+static void constant_coef( struct lp_rast_triangle *tri,
                            unsigned slot,
 			   const float value,
                            unsigned i )
@@ -54,28 +120,21 @@ static void constant_coef( struct lp_setup_context *setup,
 }
 
 
-/**
- * Compute a0, dadx and dady for a linearly interpolated coefficient,
- * for a triangle.
- */
-static void linear_coef( struct lp_setup_context *setup,
-                         struct lp_rast_triangle *tri,
-                         float oneoverarea,
+
+static void linear_coef( struct lp_rast_triangle *tri,
+                         const struct tri_info *info,
                          unsigned slot,
-                         const float (*v1)[4],
-                         const float (*v2)[4],
-                         const float (*v3)[4],
                          unsigned vert_attr,
                          unsigned i)
 {
-   float a1 = v1[vert_attr][i];
-   float a2 = v2[vert_attr][i];
-   float a3 = v3[vert_attr][i];
+   float a0 = info->v0[vert_attr][i];
+   float a1 = info->v1[vert_attr][i];
+   float a2 = info->v2[vert_attr][i];
 
-   float da12 = a1 - a2;
-   float da31 = a3 - a1;
-   float dadx = (da12 * tri->dy31 - tri->dy12 * da31) * oneoverarea;
-   float dady = (da31 * tri->dx12 - tri->dx31 * da12) * oneoverarea;
+   float da01 = a0 - a1;
+   float da20 = a2 - a0;
+   float dadx = (da01 * info->dy20 - info->dy01 * da20) * info->oneoverarea;
+   float dady = (da20 * info->dx01 - info->dx20 * da01) * info->oneoverarea;
 
    tri->inputs.dadx[slot][i] = dadx;
    tri->inputs.dady[slot][i] = dady;
@@ -92,9 +151,9 @@ static void linear_coef( struct lp_setup_context *setup,
     * to define a0 as the sample at a pixel center somewhere near vmin
     * instead - i'll switch to this later.
     */
-   tri->inputs.a0[slot][i] = (a1 -
-                              (dadx * (v1[0][0] - setup->pixel_offset) +
-                               dady * (v1[0][1] - setup->pixel_offset)));
+   tri->inputs.a0[slot][i] = (a0 -
+                              (dadx * (info->v0[0][0] - info->pixel_offset) +
+                               dady * (info->v0[0][1] - info->pixel_offset)));
 }
 
 
@@ -106,31 +165,27 @@ static void linear_coef( struct lp_setup_context *setup,
  * Later, when we compute the value at a particular fragment position we'll
  * divide the interpolated value by the interpolated W at that fragment.
  */
-static void perspective_coef( struct lp_setup_context *setup,
-                              struct lp_rast_triangle *tri,
-                              float oneoverarea,
+static void perspective_coef( struct lp_rast_triangle *tri,
+                              const struct tri_info *info,
                               unsigned slot,
-			      const float (*v1)[4],
-			      const float (*v2)[4],
-			      const float (*v3)[4],
 			      unsigned vert_attr,
                               unsigned i)
 {
    /* premultiply by 1/w  (v[0][3] is always 1/w):
     */
-   float a1 = v1[vert_attr][i] * v1[0][3];
-   float a2 = v2[vert_attr][i] * v2[0][3];
-   float a3 = v3[vert_attr][i] * v3[0][3];
-   float da12 = a1 - a2;
-   float da31 = a3 - a1;
-   float dadx = (da12 * tri->dy31 - tri->dy12 * da31) * oneoverarea;
-   float dady = (da31 * tri->dx12 - tri->dx31 * da12) * oneoverarea;
+   float a0 = info->v0[vert_attr][i] * info->v0[0][3];
+   float a1 = info->v1[vert_attr][i] * info->v1[0][3];
+   float a2 = info->v2[vert_attr][i] * info->v2[0][3];
+   float da01 = a0 - a1;
+   float da20 = a2 - a0;
+   float dadx = (da01 * info->dy20 - info->dy01 * da20) * info->oneoverarea;
+   float dady = (da20 * info->dx01 - info->dx20 * da01) * info->oneoverarea;
 
    tri->inputs.dadx[slot][i] = dadx;
    tri->inputs.dady[slot][i] = dady;
-   tri->inputs.a0[slot][i] = (a1 -
-                              (dadx * (v1[0][0] - setup->pixel_offset) +
-                               dady * (v1[0][1] - setup->pixel_offset)));
+   tri->inputs.a0[slot][i] = (a0 -
+                              (dadx * (info->v0[0][0] - info->pixel_offset) +
+                               dady * (info->v0[0][1] - info->pixel_offset)));
 }
 
 
@@ -141,13 +196,9 @@ static void perspective_coef( struct lp_setup_context *setup,
  * We could do a bit less work if we'd examine gl_FragCoord's swizzle mask.
  */
 static void
-setup_fragcoord_coef(struct lp_setup_context *setup,
-                     struct lp_rast_triangle *tri,
-                     float oneoverarea,
+setup_fragcoord_coef(struct lp_rast_triangle *tri,
+                     const struct tri_info *info,
                      unsigned slot,
-                     const float (*v1)[4],
-                     const float (*v2)[4],
-                     const float (*v3)[4],
                      unsigned usage_mask)
 {
    /*X*/
@@ -166,12 +217,12 @@ setup_fragcoord_coef(struct lp_setup_context *setup,
 
    /*Z*/
    if (usage_mask & TGSI_WRITEMASK_Z) {
-      linear_coef(setup, tri, oneoverarea, slot, v1, v2, v3, 0, 2);
+      linear_coef(tri, info, slot, 0, 2);
    }
 
    /*W*/
    if (usage_mask & TGSI_WRITEMASK_W) {
-      linear_coef(setup, tri, oneoverarea, slot, v1, v2, v3, 0, 3);
+      linear_coef(tri, info, slot, 0, 3);
    }
 }
 
@@ -180,24 +231,23 @@ setup_fragcoord_coef(struct lp_setup_context *setup,
  * Setup the fragment input attribute with the front-facing value.
  * \param frontface  is the triangle front facing?
  */
-static void setup_facing_coef( struct lp_setup_context *setup,
-                               struct lp_rast_triangle *tri,
+static void setup_facing_coef( struct lp_rast_triangle *tri,
                                unsigned slot,
                                boolean frontface,
                                unsigned usage_mask)
 {
    /* convert TRUE to 1.0 and FALSE to -1.0 */
    if (usage_mask & TGSI_WRITEMASK_X)
-      constant_coef( setup, tri, slot, 2.0f * frontface - 1.0f, 0 );
+      constant_coef( tri, slot, 2.0f * frontface - 1.0f, 0 );
 
    if (usage_mask & TGSI_WRITEMASK_Y)
-      constant_coef( setup, tri, slot, 0.0f, 1 ); /* wasted */
+      constant_coef( tri, slot, 0.0f, 1 ); /* wasted */
 
    if (usage_mask & TGSI_WRITEMASK_Z)
-      constant_coef( setup, tri, slot, 0.0f, 2 ); /* wasted */
+      constant_coef( tri, slot, 0.0f, 2 ); /* wasted */
 
    if (usage_mask & TGSI_WRITEMASK_W)
-      constant_coef( setup, tri, slot, 0.0f, 3 ); /* wasted */
+      constant_coef( tri, slot, 0.0f, 3 ); /* wasted */
 }
 
 
@@ -206,11 +256,7 @@ static void setup_facing_coef( struct lp_setup_context *setup,
  */
 static void setup_tri_coefficients( struct lp_setup_context *setup,
 				    struct lp_rast_triangle *tri,
-                                    float oneoverarea,
-				    const float (*v1)[4],
-				    const float (*v2)[4],
-				    const float (*v3)[4],
-				    boolean frontface)
+                                    const struct tri_info *info)
 {
    unsigned fragcoord_usage_mask = TGSI_WRITEMASK_XYZ;
    unsigned slot;
@@ -227,25 +273,25 @@ static void setup_tri_coefficients( struct lp_setup_context *setup,
          if (setup->flatshade_first) {
             for (i = 0; i < NUM_CHANNELS; i++)
                if (usage_mask & (1 << i))
-                  constant_coef(setup, tri, slot+1, v1[vert_attr][i], i);
+                  constant_coef(tri, slot+1, info->v0[vert_attr][i], i);
          }
          else {
             for (i = 0; i < NUM_CHANNELS; i++)
                if (usage_mask & (1 << i))
-                  constant_coef(setup, tri, slot+1, v3[vert_attr][i], i);
+                  constant_coef(tri, slot+1, info->v2[vert_attr][i], i);
          }
          break;
 
       case LP_INTERP_LINEAR:
          for (i = 0; i < NUM_CHANNELS; i++)
             if (usage_mask & (1 << i))
-               linear_coef(setup, tri, oneoverarea, slot+1, v1, v2, v3, vert_attr, i);
+               linear_coef(tri, info, slot+1, vert_attr, i);
          break;
 
       case LP_INTERP_PERSPECTIVE:
          for (i = 0; i < NUM_CHANNELS; i++)
             if (usage_mask & (1 << i))
-               perspective_coef(setup, tri, oneoverarea, slot+1, v1, v2, v3, vert_attr, i);
+               perspective_coef(tri, info, slot+1, vert_attr, i);
          fragcoord_usage_mask |= TGSI_WRITEMASK_W;
          break;
 
@@ -259,7 +305,7 @@ static void setup_tri_coefficients( struct lp_setup_context *setup,
          break;
 
       case LP_INTERP_FACING:
-         setup_facing_coef(setup, tri, slot+1, frontface, usage_mask);
+         setup_facing_coef(tri, slot+1, info->frontfacing, usage_mask);
          break;
 
       default:
@@ -269,16 +315,11 @@ static void setup_tri_coefficients( struct lp_setup_context *setup,
 
    /* The internal position input is in slot zero:
     */
-   setup_fragcoord_coef(setup, tri, oneoverarea, 0, v1, v2, v3,
-                        fragcoord_usage_mask);
+   setup_fragcoord_coef(tri, info, 0, fragcoord_usage_mask);
 }
 
 
 
-static INLINE int subpixel_snap( float a )
-{
-   return util_iround(FIXED_ONE * a - (FIXED_ONE / 2));
-}
 
 
 
@@ -291,21 +332,25 @@ static INLINE int subpixel_snap( float a )
  * \return pointer to triangle space
  */
 static INLINE struct lp_rast_triangle *
-alloc_triangle(struct lp_scene *scene, unsigned nr_inputs, unsigned *tri_size)
+alloc_triangle(struct lp_scene *scene,
+               unsigned nr_inputs,
+               unsigned nr_planes,
+               unsigned *tri_size)
 {
    unsigned input_array_sz = NUM_CHANNELS * (nr_inputs + 1) * sizeof(float);
    struct lp_rast_triangle *tri;
-   unsigned bytes;
+   unsigned tri_bytes, bytes;
    char *inputs;
 
    assert(sizeof(*tri) % 16 == 0);
 
-   bytes = sizeof(*tri) + (3 * input_array_sz);
+   tri_bytes = align(Offset(struct lp_rast_triangle, plane[nr_planes]), 16);
+   bytes = tri_bytes + (3 * input_array_sz);
 
    tri = lp_scene_alloc_aligned( scene, bytes, 16 );
 
    if (tri) {
-      inputs = (char *) (tri + 1);
+      inputs = ((char *)tri) + tri_bytes;
       tri->inputs.a0   = (float (*)[4]) inputs;
       tri->inputs.dadx = (float (*)[4]) (inputs + input_array_sz);
       tri->inputs.dady = (float (*)[4]) (inputs + 2 * input_array_sz);
@@ -329,52 +374,71 @@ print_triangle(struct lp_setup_context *setup,
    uint i;
 
    debug_printf("llvmpipe triangle\n");
-   for (i = 0; i < setup->fs.nr_inputs; i++) {
+   for (i = 0; i < 1 + setup->fs.nr_inputs; i++) {
       debug_printf("  v1[%d]:  %f %f %f %f\n", i,
                    v1[i][0], v1[i][1], v1[i][2], v1[i][3]);
    }
-   for (i = 0; i < setup->fs.nr_inputs; i++) {
+   for (i = 0; i < 1 + setup->fs.nr_inputs; i++) {
       debug_printf("  v2[%d]:  %f %f %f %f\n", i,
                    v2[i][0], v2[i][1], v2[i][2], v2[i][3]);
    }
-   for (i = 0; i < setup->fs.nr_inputs; i++) {
+   for (i = 0; i < 1 + setup->fs.nr_inputs; i++) {
       debug_printf("  v3[%d]:  %f %f %f %f\n", i,
                    v3[i][0], v3[i][1], v3[i][2], v3[i][3]);
    }
 }
 
 
+lp_rast_cmd lp_rast_tri_tab[8] = {
+   NULL,               /* should be impossible */
+   lp_rast_triangle_1,
+   lp_rast_triangle_2,
+   lp_rast_triangle_3,
+   lp_rast_triangle_4,
+   lp_rast_triangle_5,
+   lp_rast_triangle_6,
+   lp_rast_triangle_7
+};
+
 /**
  * Do basic setup for triangle rasterization and determine which
  * framebuffer tiles are touched.  Put the triangle in the scene's
  * bins for the tiles which we overlap.
  */
-static void 
+static void
 do_triangle_ccw(struct lp_setup_context *setup,
 		const float (*v1)[4],
 		const float (*v2)[4],
 		const float (*v3)[4],
 		boolean frontfacing )
 {
-   /* x/y positions in fixed point */
-   const int x1 = subpixel_snap(v1[0][0] + 0.5 - setup->pixel_offset);
-   const int x2 = subpixel_snap(v2[0][0] + 0.5 - setup->pixel_offset);
-   const int x3 = subpixel_snap(v3[0][0] + 0.5 - setup->pixel_offset);
-   const int y1 = subpixel_snap(v1[0][1] + 0.5 - setup->pixel_offset);
-   const int y2 = subpixel_snap(v2[0][1] + 0.5 - setup->pixel_offset);
-   const int y3 = subpixel_snap(v3[0][1] + 0.5 - setup->pixel_offset);
 
    struct lp_scene *scene = lp_setup_get_current_scene(setup);
+   struct lp_fragment_shader_variant *variant = setup->fs.current.variant;
    struct lp_rast_triangle *tri;
+   struct tri_info info;
    int area;
-   float oneoverarea;
    int minx, maxx, miny, maxy;
+   int ix0, ix1, iy0, iy1;
    unsigned tri_bytes;
-
+   int i;
+   int nr_planes = 3;
+      
    if (0)
       print_triangle(setup, v1, v2, v3);
 
-   tri = alloc_triangle(scene, setup->fs.nr_inputs, &tri_bytes);
+   if (setup->scissor_test) {
+      nr_planes = 7;
+   }
+   else {
+      nr_planes = 3;
+   }
+
+
+   tri = alloc_triangle(scene,
+                        setup->fs.nr_inputs,
+                        nr_planes,
+                        &tri_bytes);
    if (!tri)
       return;
 
@@ -387,15 +451,24 @@ do_triangle_ccw(struct lp_setup_context *setup,
    tri->v[2][1] = v3[0][1];
 #endif
 
-   tri->dx12 = x1 - x2;
-   tri->dx23 = x2 - x3;
-   tri->dx31 = x3 - x1;
+   /* x/y positions in fixed point */
+   info.x[0] = subpixel_snap(v1[0][0] - setup->pixel_offset);
+   info.x[1] = subpixel_snap(v2[0][0] - setup->pixel_offset);
+   info.x[2] = subpixel_snap(v3[0][0] - setup->pixel_offset);
+   info.y[0] = subpixel_snap(v1[0][1] - setup->pixel_offset);
+   info.y[1] = subpixel_snap(v2[0][1] - setup->pixel_offset);
+   info.y[2] = subpixel_snap(v3[0][1] - setup->pixel_offset);
+
+   tri->plane[0].dcdy = info.x[0] - info.x[1];
+   tri->plane[1].dcdy = info.x[1] - info.x[2];
+   tri->plane[2].dcdy = info.x[2] - info.x[0];
 
-   tri->dy12 = y1 - y2;
-   tri->dy23 = y2 - y3;
-   tri->dy31 = y3 - y1;
+   tri->plane[0].dcdx = info.y[0] - info.y[1];
+   tri->plane[1].dcdx = info.y[1] - info.y[2];
+   tri->plane[2].dcdx = info.y[2] - info.y[0];
 
-   area = (tri->dx12 * tri->dy31 - tri->dx31 * tri->dy12);
+   area = (tri->plane[0].dcdy * tri->plane[2].dcdx -
+           tri->plane[2].dcdy * tri->plane[0].dcdx);
 
    LP_COUNT(nr_tris);
 
@@ -410,20 +483,35 @@ do_triangle_ccw(struct lp_setup_context *setup,
    }
 
    /* Bounding rectangle (in pixels) */
-   minx = (MIN3(x1, x2, x3) + (FIXED_ONE-1)) >> FIXED_ORDER;
-   maxx = (MAX3(x1, x2, x3) + (FIXED_ONE-1)) >> FIXED_ORDER;
-   miny = (MIN3(y1, y2, y3) + (FIXED_ONE-1)) >> FIXED_ORDER;
-   maxy = (MAX3(y1, y2, y3) + (FIXED_ONE-1)) >> FIXED_ORDER;
-   
+   {
+      /* Yes this is necessary to accurately calculate bounding boxes
+       * with the two fill-conventions we support.  GL (normally) ends
+       * up needing a bottom-left fill convention, which requires
+       * slightly different rounding.
+       */
+      int adj = (setup->pixel_offset != 0) ? 1 : 0;
+
+      minx = (MIN3(info.x[0], info.x[1], info.x[2]) + (FIXED_ONE-1)) >> FIXED_ORDER;
+      maxx = (MAX3(info.x[0], info.x[1], info.x[2]) + (FIXED_ONE-1)) >> FIXED_ORDER;
+      miny = (MIN3(info.y[0], info.y[1], info.y[2]) + (FIXED_ONE-1) + adj) >> FIXED_ORDER;
+      maxy = (MAX3(info.y[0], info.y[1], info.y[2]) + (FIXED_ONE-1) + adj) >> FIXED_ORDER;
+   }
+
    if (setup->scissor_test) {
       minx = MAX2(minx, setup->scissor.current.minx);
       maxx = MIN2(maxx, setup->scissor.current.maxx);
       miny = MAX2(miny, setup->scissor.current.miny);
       maxy = MIN2(maxy, setup->scissor.current.maxy);
    }
+   else {
+      minx = MAX2(minx, 0);
+      miny = MAX2(miny, 0);
+      maxx = MIN2(maxx, scene->fb.width);
+      maxy = MIN2(maxy, scene->fb.height);
+   }
+
 
-   if (miny == maxy || 
-       minx == maxx) {
+   if (miny >= maxy || minx >= maxx) {
       lp_scene_putback_data( scene, tri_bytes );
       LP_COUNT(nr_culled_tris);
       return;
@@ -431,75 +519,87 @@ do_triangle_ccw(struct lp_setup_context *setup,
 
    /* 
     */
-   oneoverarea = ((float)FIXED_ONE) / (float)area;
+   info.pixel_offset = setup->pixel_offset;
+   info.v0 = v1;
+   info.v1 = v2;
+   info.v2 = v3;
+   info.dx01 = info.v0[0][0] - info.v1[0][0];
+   info.dx20 = info.v2[0][0] - info.v0[0][0];
+   info.dy01 = info.v0[0][1] - info.v1[0][1];
+   info.dy20 = info.v2[0][1] - info.v0[0][1];
+   info.oneoverarea = 1.0 / (info.dx01 * info.dy20 - info.dx20 * info.dy01);
+   info.frontfacing = frontfacing;
 
    /* Setup parameter interpolants:
     */
-   setup_tri_coefficients( setup, tri, oneoverarea, v1, v2, v3, frontfacing );
+   setup_tri_coefficients( setup, tri, &info );
 
    tri->inputs.facing = frontfacing ? 1.0F : -1.0F;
 
-   /* half-edge constants, will be interated over the whole render target.
-    */
-   tri->c1 = tri->dy12 * x1 - tri->dx12 * y1;
-   tri->c2 = tri->dy23 * x2 - tri->dx23 * y2;
-   tri->c3 = tri->dy31 * x3 - tri->dx31 * y3;
 
-   /* correct for top-left fill convention:
-    */
-   if (tri->dy12 < 0 || (tri->dy12 == 0 && tri->dx12 > 0)) tri->c1++;
-   if (tri->dy23 < 0 || (tri->dy23 == 0 && tri->dx23 > 0)) tri->c2++;
-   if (tri->dy31 < 0 || (tri->dy31 == 0 && tri->dx31 > 0)) tri->c3++;
-
-   tri->dy12 *= FIXED_ONE;
-   tri->dy23 *= FIXED_ONE;
-   tri->dy31 *= FIXED_ONE;
-
-   tri->dx12 *= FIXED_ONE;
-   tri->dx23 *= FIXED_ONE;
-   tri->dx31 *= FIXED_ONE;
-
-   /* find trivial reject offsets for each edge for a single-pixel
-    * sized block.  These will be scaled up at each recursive level to
-    * match the active blocksize.  Scaling in this way works best if
-    * the blocks are square.
-    */
-   tri->eo1 = 0;
-   if (tri->dy12 < 0) tri->eo1 -= tri->dy12;
-   if (tri->dx12 > 0) tri->eo1 += tri->dx12;
+  
+   for (i = 0; i < 3; i++) {
+      struct lp_rast_plane *plane = &tri->plane[i];
 
-   tri->eo2 = 0;
-   if (tri->dy23 < 0) tri->eo2 -= tri->dy23;
-   if (tri->dx23 > 0) tri->eo2 += tri->dx23;
+      /* half-edge constants, will be interated over the whole render
+       * target.
+       */
+      plane->c = plane->dcdx * info.x[i] - plane->dcdy * info.y[i];
+
+      /* correct for top-left vs. bottom-left fill convention.  
+       *
+       * note that we're overloading gl_rasterization_rules to mean
+       * both (0.5,0.5) pixel centers *and* bottom-left filling
+       * convention.
+       *
+       * GL actually has a top-left filling convention, but GL's
+       * notion of "top" differs from gallium's...
+       *
+       * Also, sometimes (in FBO cases) GL will render upside down
+       * to its usual method, in which case it will probably want
+       * to use the opposite, top-left convention.
+       */         
+      if (plane->dcdx < 0) {
+         /* both fill conventions want this - adjust for left edges */
+         plane->c++;            
+      }
+      else if (plane->dcdx == 0) {
+         if (setup->pixel_offset == 0) {
+            /* correct for top-left fill convention:
+             */
+            if (plane->dcdy > 0) plane->c++;
+         }
+         else {
+            /* correct for bottom-left fill convention:
+             */
+            if (plane->dcdy < 0) plane->c++;
+         }
+      }
 
-   tri->eo3 = 0;
-   if (tri->dy31 < 0) tri->eo3 -= tri->dy31;
-   if (tri->dx31 > 0) tri->eo3 += tri->dx31;
+      plane->dcdx *= FIXED_ONE;
+      plane->dcdy *= FIXED_ONE;
 
-   /* Calculate trivial accept offsets from the above.
-    */
-   tri->ei1 = tri->dx12 - tri->dy12 - tri->eo1;
-   tri->ei2 = tri->dx23 - tri->dy23 - tri->eo2;
-   tri->ei3 = tri->dx31 - tri->dy31 - tri->eo3;
+      /* find trivial reject offsets for each edge for a single-pixel
+       * sized block.  These will be scaled up at each recursive level to
+       * match the active blocksize.  Scaling in this way works best if
+       * the blocks are square.
+       */
+      plane->eo = 0;
+      if (plane->dcdx < 0) plane->eo -= plane->dcdx;
+      if (plane->dcdy > 0) plane->eo += plane->dcdy;
 
-   /* Fill in the inputs.step[][] arrays.
-    * We've manually unrolled some loops here.
-    */
-   {
-      const int xstep1 = -tri->dy12;
-      const int xstep2 = -tri->dy23;
-      const int xstep3 = -tri->dy31;
-      const int ystep1 = tri->dx12;
-      const int ystep2 = tri->dx23;
-      const int ystep3 = tri->dx31;
-
-#define SETUP_STEP(i, x, y)                                \
-      do {                                                 \
-         tri->inputs.step[0][i] = x * xstep1 + y * ystep1; \
-         tri->inputs.step[1][i] = x * xstep2 + y * ystep2; \
-         tri->inputs.step[2][i] = x * xstep3 + y * ystep3; \
-      } while (0)
+      /* Calculate trivial accept offsets from the above.
+       */
+      plane->ei = plane->dcdy - plane->dcdx - plane->eo;
 
+      plane->step = tri->step[i];
+
+      /* Fill in the inputs.step[][] arrays.
+       * We've manually unrolled some loops here.
+       */
+#define SETUP_STEP(j, x, y) \
+      tri->step[i][j] = y * plane->dcdy - x * plane->dcdx
+      
       SETUP_STEP(0, 0, 0);
       SETUP_STEP(1, 1, 0);
       SETUP_STEP(2, 0, 1);
@@ -522,63 +622,106 @@ do_triangle_ccw(struct lp_setup_context *setup,
 #undef STEP
    }
 
+
+   /* 
+    * When rasterizing scissored tris, use the intersection of the
+    * triangle bounding box and the scissor rect to generate the
+    * scissor planes.
+    *
+    * This permits us to cut off the triangle "tails" that are present
+    * in the intermediate recursive levels caused when two of the
+    * triangles edges don't diverge quickly enough to trivially reject
+    * exterior blocks from the triangle.
+    *
+    * It's not really clear if it's worth worrying about these tails,
+    * but since we generate the planes for each scissored tri, it's
+    * free to trim them in this case.
+    * 
+    * Note that otherwise, the scissor planes only vary in 'C' value,
+    * and even then only on state-changes.  Could alternatively store
+    * these planes elsewhere.
+    */
+   if (nr_planes == 7) {
+      tri->plane[3].step = step_scissor_minx;
+      tri->plane[3].dcdx = -1;
+      tri->plane[3].dcdy = 0;
+      tri->plane[3].c = 1-minx;
+      tri->plane[3].ei = 0;
+      tri->plane[3].eo = 1;
+
+      tri->plane[4].step = step_scissor_maxx;
+      tri->plane[4].dcdx = 1;
+      tri->plane[4].dcdy = 0;
+      tri->plane[4].c = maxx;
+      tri->plane[4].ei = -1;
+      tri->plane[4].eo = 0;
+
+      tri->plane[5].step = step_scissor_miny;
+      tri->plane[5].dcdx = 0;
+      tri->plane[5].dcdy = 1;
+      tri->plane[5].c = 1-miny;
+      tri->plane[5].ei = 0;
+      tri->plane[5].eo = 1;
+
+      tri->plane[6].step = step_scissor_maxy;
+      tri->plane[6].dcdx = 0;
+      tri->plane[6].dcdy = -1;
+      tri->plane[6].c = maxy;
+      tri->plane[6].ei = -1;
+      tri->plane[6].eo = 0;
+   }
+
+
    /*
     * All fields of 'tri' are now set.  The remaining code here is
     * concerned with binning.
     */
 
-   /* Convert to tile coordinates:
+   /* Convert to tile coordinates, and inclusive ranges:
     */
-   minx = minx / TILE_SIZE;
-   miny = miny / TILE_SIZE;
-   maxx = maxx / TILE_SIZE;
-   maxy = maxy / TILE_SIZE;
+   ix0 = minx / TILE_SIZE;
+   iy0 = miny / TILE_SIZE;
+   ix1 = (maxx-1) / TILE_SIZE;
+   iy1 = (maxy-1) / TILE_SIZE;
 
    /*
     * Clamp to framebuffer size
     */
-   minx = MAX2(minx, 0);
-   miny = MAX2(miny, 0);
-   maxx = MIN2(maxx, scene->tiles_x - 1);
-   maxy = MIN2(maxy, scene->tiles_y - 1);
+   assert(ix0 == MAX2(ix0, 0));
+   assert(iy0 == MAX2(iy0, 0));
+   assert(ix1 == MIN2(ix1, scene->tiles_x - 1));
+   assert(iy1 == MIN2(iy1, scene->tiles_y - 1));
 
    /* Determine which tile(s) intersect the triangle's bounding box
     */
-   if (miny == maxy && minx == maxx)
+   if (iy0 == iy1 && ix0 == ix1)
    {
       /* Triangle is contained in a single tile:
        */
-      lp_scene_bin_command( scene, minx, miny, lp_rast_triangle, 
-			    lp_rast_arg_triangle(tri) );
+      lp_scene_bin_command( scene, ix0, iy0,
+                            lp_rast_tri_tab[nr_planes], 
+			    lp_rast_arg_triangle(tri, (1<<nr_planes)-1) );
    }
-   else 
+   else
    {
-      int c1 = (tri->c1 + 
-                tri->dx12 * miny * TILE_SIZE - 
-                tri->dy12 * minx * TILE_SIZE);
-      int c2 = (tri->c2 + 
-                tri->dx23 * miny * TILE_SIZE -
-                tri->dy23 * minx * TILE_SIZE);
-      int c3 = (tri->c3 +
-                tri->dx31 * miny * TILE_SIZE -
-                tri->dy31 * minx * TILE_SIZE);
-
-      int ei1 = tri->ei1 << TILE_ORDER;
-      int ei2 = tri->ei2 << TILE_ORDER;
-      int ei3 = tri->ei3 << TILE_ORDER;
-
-      int eo1 = tri->eo1 << TILE_ORDER;
-      int eo2 = tri->eo2 << TILE_ORDER;
-      int eo3 = tri->eo3 << TILE_ORDER;
-
-      int xstep1 = -(tri->dy12 << TILE_ORDER);
-      int xstep2 = -(tri->dy23 << TILE_ORDER);
-      int xstep3 = -(tri->dy31 << TILE_ORDER);
-
-      int ystep1 = tri->dx12 << TILE_ORDER;
-      int ystep2 = tri->dx23 << TILE_ORDER;
-      int ystep3 = tri->dx31 << TILE_ORDER;
+      int c[7];
+      int ei[7];
+      int eo[7];
+      int xstep[7];
+      int ystep[7];
       int x, y;
+      
+      for (i = 0; i < nr_planes; i++) {
+         c[i] = (tri->plane[i].c + 
+                 tri->plane[i].dcdy * iy0 * TILE_SIZE - 
+                 tri->plane[i].dcdx * ix0 * TILE_SIZE);
+
+         ei[i] = tri->plane[i].ei << TILE_ORDER;
+         eo[i] = tri->plane[i].eo << TILE_ORDER;
+         xstep[i] = -(tri->plane[i].dcdx << TILE_ORDER);
+         ystep[i] = tri->plane[i].dcdy << TILE_ORDER;
+      }
+
 
 
       /* Test tile-sized blocks against the triangle.
@@ -586,32 +729,49 @@ do_triangle_ccw(struct lp_setup_context *setup,
        * contained inside the tri, bin an lp_rast_shade_tile command.
        * Else, bin a lp_rast_triangle command.
        */
-      for (y = miny; y <= maxy; y++)
+      for (y = iy0; y <= iy1; y++)
       {
-	 int cx1 = c1;
-	 int cx2 = c2;
-	 int cx3 = c3;
 	 boolean in = FALSE;  /* are we inside the triangle? */
+	 int cx[7];
+
+         for (i = 0; i < nr_planes; i++)
+            cx[i] = c[i];
 
-	 for (x = minx; x <= maxx; x++)
+	 for (x = ix0; x <= ix1; x++)
 	 {
-	    if (cx1 + eo1 < 0 || 
-		cx2 + eo2 < 0 ||
-		cx3 + eo3 < 0) 
-	    {
-	       /* do nothing */
+            int out = 0;
+            int partial = 0;
+
+            for (i = 0; i < nr_planes; i++) {
+               int planeout = cx[i] + eo[i];
+               int planepartial = cx[i] + ei[i] - 1;
+               out |= (planeout >> 31);
+               partial |= (planepartial >> 31) & (1<<i);
+            }
+
+            if (out) {
+               /* do nothing */
+               if (in)
+                  break;  /* exiting triangle, all done with this row */
                LP_COUNT(nr_empty_64);
-	       if (in)
-		  break;  /* exiting triangle, all done with this row */
-	    }
-	    else if (cx1 + ei1 > 0 &&
-		     cx2 + ei2 > 0 &&
-		     cx3 + ei3 > 0) 
-	    {
+            }
+            else if (partial) {
+               /* Not trivially accepted by at least one plane - 
+                * rasterize/shade partial tile
+                */
+               int count = util_bitcount(partial);
+               in = TRUE;
+               lp_scene_bin_command( scene, x, y,
+                                     lp_rast_tri_tab[count], 
+                                     lp_rast_arg_triangle(tri, partial) );
+
+               LP_COUNT(nr_partially_covered_64);
+            }
+            else {
                /* triangle covers the whole tile- shade whole tile */
                LP_COUNT(nr_fully_covered_64);
-	       in = TRUE;
-	       if (setup->fs.current.variant->opaque &&
+               in = TRUE;
+	       if (variant->opaque &&
 	           !setup->fb.zsbuf) {
 	          lp_scene_bin_reset( scene, x, y );
 	          lp_scene_bin_command( scene, x, y,
@@ -621,29 +781,18 @@ do_triangle_ccw(struct lp_setup_context *setup,
                lp_scene_bin_command( scene, x, y,
 				     lp_rast_shade_tile,
 				     lp_rast_arg_inputs(&tri->inputs) );
-	    }
-	    else 
-	    { 
-               /* rasterizer/shade partial tile */
-               LP_COUNT(nr_partially_covered_64);
-	       in = TRUE;
-               lp_scene_bin_command( scene, x, y,
-				     lp_rast_triangle, 
-				     lp_rast_arg_triangle(tri) );
-	    }
+            }
 
 	    /* Iterate cx values across the region:
 	     */
-	    cx1 += xstep1;
-	    cx2 += xstep2;
-	    cx3 += xstep3;
+            for (i = 0; i < nr_planes; i++)
+               cx[i] += xstep[i];
 	 }
       
 	 /* Iterate c values down the region:
 	  */
-	 c1 += ystep1;
-	 c2 += ystep2;
-	 c3 += ystep3;    
+         for (i = 0; i < nr_planes; i++)
+            c[i] += ystep[i];
       }
    }
 }