llvmpipe: avoid left-shifting a negative number.

[mesa.git] / src / gallium / drivers / llvmpipe / lp_setup_line.c

diff --git a/src/gallium/drivers/llvmpipe/lp_setup_line.c b/src/gallium/drivers/llvmpipe/lp_setup_line.c
index a0de599c9c61619f79b870710d8945af91d429b3..5e26b1e9ffc08a8eca2e3b297d6428c7829f019f 100644 (file)
--- a/src/gallium/drivers/llvmpipe/lp_setup_line.c
+++ b/src/gallium/drivers/llvmpipe/lp_setup_line.c
@@ -288,7 +288,9 @@ try_setup_line( struct lp_setup_context *setup,
    struct lp_rast_plane *plane;
    struct lp_line_info info;
    float width = MAX2(1.0, setup->line_width);
-   struct u_rect bbox;
+   const struct u_rect *scissor;
+   struct u_rect bbox, bboxpos;
+   boolean s_planes[4];
    unsigned tri_bytes;
    int x[4]; 
    int y[4];
@@ -336,13 +338,6 @@ try_setup_line( struct lp_setup_context *setup,
       layer = MIN2(layer, scene->fb_max_layer);
    }
 
-   if (setup->scissor_test) {
-      nr_planes = 8;
-   }
-   else {
-      nr_planes = 4;
-   }
-
    dx = v1[0][0] - v2[0][0];
    dy = v1[0][1] - v2[0][1];
    area = (dx * dx  + dy * dy);
@@ -586,10 +581,24 @@ try_setup_line( struct lp_setup_context *setup,
       return TRUE;
    }
 
+   bboxpos = bbox;
+
    /* Can safely discard negative regions:
     */
-   bbox.x0 = MAX2(bbox.x0, 0);
-   bbox.y0 = MAX2(bbox.y0, 0);
+   bboxpos.x0 = MAX2(bboxpos.x0, 0);
+   bboxpos.y0 = MAX2(bboxpos.y0, 0);
+
+   nr_planes = 4;
+   /*
+    * Determine how many scissor planes we need, that is drop scissor
+    * edges if the bounding box of the tri is fully inside that edge.
+    */
+   if (setup->scissor_test) {
+      /* why not just use draw_regions */
+      scissor = &setup->scissors[viewport_index];
+      scissor_planes_needed(s_planes, &bboxpos, scissor);
+      nr_planes += s_planes[0] + s_planes[1] + s_planes[2] + s_planes[3];
+   }
 
    line = lp_setup_alloc_triangle(scene,
                                   key->num_inputs,
@@ -607,8 +616,7 @@ try_setup_line( struct lp_setup_context *setup,
 
    LP_COUNT(nr_tris);
 
-   if (lp_context->active_statistics_queries &&
-       !llvmpipe_rasterization_disabled(lp_context)) {
+   if (lp_context->active_statistics_queries) {
       lp_context->pipeline_statistics.c_primitives++;
    }
 
@@ -708,54 +716,75 @@ try_setup_line( struct lp_setup_context *setup,
     * Note that otherwise, the scissor planes only vary in 'C' value,
     * and even then only on state-changes.  Could alternatively store
     * these planes elsewhere.
+    * (Or only store the c value together with a bit indicating which
+    * scissor edge this is, so rasterization would treat them differently
+    * (easier to evaluate) to ordinary planes.)
     */
-   if (nr_planes == 8) {
-      const struct u_rect *scissor =
-         &setup->scissors[viewport_index];
-
-      plane[4].dcdx = -1;
-      plane[4].dcdy = 0;
-      plane[4].c = 1-scissor->x0;
-      plane[4].eo = 1;
-
-      plane[5].dcdx = 1;
-      plane[5].dcdy = 0;
-      plane[5].c = scissor->x1+1;
-      plane[5].eo = 0;
-
-      plane[6].dcdx = 0;
-      plane[6].dcdy = 1;
-      plane[6].c = 1-scissor->y0;
-      plane[6].eo = 1;
-
-      plane[7].dcdx = 0;
-      plane[7].dcdy = -1;
-      plane[7].c = scissor->y1+1;
-      plane[7].eo = 0;
+   if (nr_planes > 4) {
+      struct lp_rast_plane *plane_s = &plane[4];
+
+      if (s_planes[0]) {
+         plane_s->dcdx = ~0U << 8;
+         plane_s->dcdy = 0;
+         plane_s->c = (1-scissor->x0) << 8;
+         plane_s->eo = 1 << 8;
+         plane_s++;
+      }
+      if (s_planes[1]) {
+         plane_s->dcdx = 1 << 8;
+         plane_s->dcdy = 0;
+         plane_s->c = (scissor->x1+1) << 8;
+         plane_s->eo = 0 << 8;
+         plane_s++;
+      }
+      if (s_planes[2]) {
+         plane_s->dcdx = 0;
+         plane_s->dcdy = 1 << 8;
+         plane_s->c = (1-scissor->y0) << 8;
+         plane_s->eo = 1 << 8;
+         plane_s++;
+      }
+      if (s_planes[3]) {
+         plane_s->dcdx = 0;
+         plane_s->dcdy = ~0U << 8;
+         plane_s->c = (scissor->y1+1) << 8;
+         plane_s->eo = 0;
+         plane_s++;
+      }
+      assert(plane_s == &plane[nr_planes]);
    }
 
-   return lp_setup_bin_triangle(setup, line, &bbox, nr_planes, viewport_index);
+   return lp_setup_bin_triangle(setup, line, &bbox, &bboxpos, nr_planes, viewport_index);
 }
 
 
-static void lp_setup_line( struct lp_setup_context *setup,
-                           const float (*v0)[4],
-                           const float (*v1)[4] )
+static void lp_setup_line_discard(struct lp_setup_context *setup,
+                                  const float (*v0)[4],
+                                  const float (*v1)[4])
 {
-   if (!try_setup_line( setup, v0, v1 ))
-   {
+}
+
+static void lp_setup_line(struct lp_setup_context *setup,
+                          const float (*v0)[4],
+                          const float (*v1)[4])
+{
+   if (!try_setup_line(setup, v0, v1)) {
       if (!lp_setup_flush_and_restart(setup))
          return;
 
-      if (!try_setup_line( setup, v0, v1 ))
+      if (!try_setup_line(setup, v0, v1))
          return;
    }
 }
 
 
-void lp_setup_choose_line( struct lp_setup_context *setup ) 
+void lp_setup_choose_line(struct lp_setup_context *setup)
 { 
-   setup->line = lp_setup_line;
+   if (setup->rasterizer_discard) {
+      setup->line = lp_setup_line_discard;
+   } else {
+      setup->line = lp_setup_line;
+   }
 }