llvmpipe: native rasterization for lines

Rasterize lines directly by treating them as 4-sided polygons.
Still need to check the exact pixel rasteration.

1 files changed, 611 insertions, 6 deletions

diff --git a/src/gallium/drivers/llvmpipe/lp_setup_line.c b/src/gallium/drivers/llvmpipe/lp_setup_line.c
index be41c44e6f..930207ae33 100644
--- a/src/gallium/drivers/llvmpipe/lp_setup_line.c
+++ b/src/gallium/drivers/llvmpipe/lp_setup_line.c
@@ -29,19 +29,624 @@
  * Binning code for lines
  */
 
+#include "util/u_math.h"
+#include "util/u_memory.h"
+#include "lp_perf.h"
 #include "lp_setup_context.h"
+#include "lp_rast.h"
+#include "lp_state_fs.h"
 
-static void line_nop( struct lp_setup_context *setup,
-                      const float (*v0)[4],
-                      const float (*v1)[4] )
+#define NUM_CHANNELS 4
+
+
+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
+};
+
+
+
+/**
+ * Compute a0 for a constant-valued coefficient (GL_FLAT shading).
+ */
+static void constant_coef( struct lp_setup_context *setup,
+                           struct lp_rast_triangle *tri,
+                           unsigned slot,
+                           const float value,
+                           unsigned i )
+{
+   tri->inputs.a0[slot][i] = value;
+   tri->inputs.dadx[slot][i] = 0.0f;
+   tri->inputs.dady[slot][i] = 0.0f;
+}
+
+
+/**
+ * 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,
+                         unsigned slot,
+                         const float (*v1)[4],
+                         const float (*v2)[4],
+                         unsigned vert_attr,
+                         unsigned i)
+{
+   float a1 = v1[vert_attr][i]; 
+   float a2 = v2[vert_attr][i];
+      
+   float da21 = a1 - a2;   
+   float dadx = da21 * tri->dx * oneoverarea;
+   float dady = da21 * tri->dy * 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)));
+}
+
+
+/**
+ * Compute a0, dadx and dady for a perspective-corrected interpolant,
+ * for a triangle.
+ * We basically multiply the vertex value by 1/w before computing
+ * the plane coefficients (a0, dadx, dady).
+ * 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,
+                              unsigned slot,
+                              const float (*v1)[4],
+                              const float (*v2)[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 da21 = a1 - a2;   
+   float dadx = da21 * tri->dx * oneoverarea;
+   float dady = da21 * tri->dy * 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)));
+}
+
+/**
+ * Compute the tri->coef[] array dadx, dady, a0 values.
+ */
+static void setup_line_coefficients( struct lp_setup_context *setup,
+                                     struct lp_rast_triangle *tri,
+                                     float oneoverarea,
+                                     const float (*v1)[4],
+                                     const float (*v2)[4])
 {
+   unsigned fragcoord_usage_mask = TGSI_WRITEMASK_XYZ;
+   unsigned slot;
+
+   /* setup interpolation for all the remaining attributes:
+    */
+   for (slot = 0; slot < setup->fs.nr_inputs; slot++) {
+      unsigned vert_attr = setup->fs.input[slot].src_index;
+      unsigned usage_mask = setup->fs.input[slot].usage_mask;
+      unsigned i;
+           
+      switch (setup->fs.input[slot].interp) {
+      case LP_INTERP_CONSTANT:
+         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);
+         }
+         else {
+            for (i = 0; i < NUM_CHANNELS; i++)
+               if (usage_mask & (1 << i))
+                  constant_coef(setup, tri, slot+1, 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, 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, vert_attr, i);
+         fragcoord_usage_mask |= TGSI_WRITEMASK_W;
+         break;
+
+      case LP_INTERP_POSITION:
+         /*
+          * The generated pixel interpolators will pick up the coeffs from
+          * slot 0, so all need to ensure that the usage mask is covers all
+          * usages.
+          */
+         fragcoord_usage_mask |= usage_mask;
+         break;
+
+      default:
+         assert(0);
+      }
+   }
+
+   /* The internal position input is in slot zero:
+    */
+   lp_setup_fragcoord_coef(setup, tri, oneoverarea, 0, v1, v2, v2,
+                            fragcoord_usage_mask);
 }
 
 
-void 
-lp_setup_choose_line( struct lp_setup_context *setup )
+
+static INLINE int subpixel_snap( float a )
 {
-   setup->line = line_nop;
+   return util_iround(FIXED_ONE * a);
+}
+
+
+/**
+ * Print line vertex attribs (for debug).
+ */
+static void
+print_line(struct lp_setup_context *setup,
+           const float (*v1)[4],
+           const float (*v2)[4])
+{
+   uint i;
+
+   debug_printf("llvmpipe line\n");
+   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 < 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]);
+   }
+}
+
+
+static void
+lp_setup_line( struct lp_setup_context *setup,
+               const float (*v1)[4],
+               const float (*v2)[4])
+{
+   struct lp_scene *scene = lp_setup_get_current_scene(setup);
+   struct lp_rast_triangle *line;
+   float oneoverarea;
+   float half_width = setup->line_width / 2;
+   int minx, maxx, miny, maxy;
+   int ix0, ix1, iy0, iy1;
+   unsigned tri_bytes;
+   int x[4]; 
+   int y[4];
+   int i;
+   int nr_planes = 4;
+   boolean opaque;
+         
+   if (0)
+      print_line(setup, v1, v2);
+
+   if (setup->scissor_test) {
+      nr_planes = 8;
+   }
+   else {
+      nr_planes = 4;
+   }
+
+   line = lp_setup_alloc_triangle(scene,
+                                  setup->fs.nr_inputs,
+                                  nr_planes,
+                                  &tri_bytes);
+   if (!line)
+      return;
+
+#ifndef DEBUG
+   line->v[0][0] = v1[0][0];
+   line->v[1][0] = v2[0][0];   
+   line->v[0][1] = v1[0][1];
+   line->v[1][1] = v2[0][1];
+#endif
+
+   /* pre-calculation(based on given vertices) to determine if line is
+    * more horizontal or more vertical
+    */
+   line->dx = v1[0][0] - v2[0][0];
+   line->dy = v1[0][1] - v2[0][1];
+   
+   /* x-major line */
+   if (fabsf(line->dx) >= fabsf(line->dy)) {
+      if (line->dx < 0) {
+         /* if v2 is to the right of v1, swap pointers */
+         const float (*temp)[4] = v1;
+         v1 = v2;
+         v2 = temp;
+         line->dx = -line->dx;
+         line->dy = -line->dy;
+      }
+      
+      /* x/y positions in fixed point */
+      x[0] = subpixel_snap(v1[0][0] - setup->pixel_offset);
+      x[1] = subpixel_snap(v2[0][0] - setup->pixel_offset);
+      x[2] = subpixel_snap(v2[0][0] - setup->pixel_offset);
+      x[3] = subpixel_snap(v1[0][0] - setup->pixel_offset);
+      
+      y[0] = subpixel_snap(v1[0][1] - half_width - setup->pixel_offset);
+      y[1] = subpixel_snap(v2[0][1] - half_width - setup->pixel_offset);
+      y[2] = subpixel_snap(v2[0][1] + half_width - setup->pixel_offset);
+      y[3] = subpixel_snap(v1[0][1] + half_width - setup->pixel_offset);
+   }
+   else{
+      /* y-major line */
+      if (line->dy > 0) {
+         /* if v2 is on top of v1, swap pointers */
+         const float (*temp)[4] = v1;
+         v1 = v2;
+         v2 = temp; 
+         line->dx = -line->dx;
+         line->dy = -line->dy;
+      }
+ 
+      x[0] = subpixel_snap(v1[0][0] - half_width - setup->pixel_offset);
+      x[1] = subpixel_snap(v2[0][0] - half_width - setup->pixel_offset);
+      x[2] = subpixel_snap(v2[0][0] + half_width - setup->pixel_offset);
+      x[3] = subpixel_snap(v1[0][0] + half_width - setup->pixel_offset);
+     
+      y[0] = subpixel_snap(v1[0][1] - setup->pixel_offset);
+      y[1] = subpixel_snap(v2[0][1] - setup->pixel_offset);
+      y[2] = subpixel_snap(v2[0][1] - setup->pixel_offset);
+      y[3] = subpixel_snap(v1[0][1] - setup->pixel_offset);
+   }
+
+   /* calculate the deltas */
+   line->plane[0].dcdy = x[0] - x[1];
+   line->plane[1].dcdy = x[1] - x[2];
+   line->plane[2].dcdy = x[2] - x[3];
+   line->plane[3].dcdy = x[3] - x[0];
+
+   line->plane[0].dcdx = y[0] - y[1];
+   line->plane[1].dcdx = y[1] - y[2];
+   line->plane[2].dcdx = y[2] - y[3];
+   line->plane[3].dcdx = y[3] - y[0];
+
+
+   LP_COUNT(nr_tris);
+
+ 
+   /* Bounding rectangle (in pixels) */
+   {
+      /* 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 = (MIN4(x[0], x[1], x[2], x[3]) + (FIXED_ONE-1)) >> FIXED_ORDER;
+      maxx = (MAX4(x[0], x[1], x[2], x[3]) + (FIXED_ONE-1)) >> FIXED_ORDER;
+      miny = (MIN4(y[0], y[1], y[3], y[3]) + (FIXED_ONE-1) + adj) >> FIXED_ORDER;
+      maxy = (MAX4(y[0], y[1], y[3], y[3]) + (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) {
+      lp_scene_putback_data( scene, tri_bytes );
+      return;
+   }
+
+   oneoverarea = 1.0f / (line->dx * line->dx  + line->dy * line->dy);    
+
+   /* Setup parameter interpolants:
+    */
+   setup_line_coefficients( setup, line, oneoverarea, v1, v2); 
+
+   for (i = 0; i < 4; i++) {
+      struct lp_rast_plane *plane = &line->plane[i];
+
+      /* half-edge constants, will be interated over the whole render
+       * target.
+       */
+      plane->c = plane->dcdx * x[i] - plane->dcdy * 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++;
+         }
+      }
+
+      plane->dcdx *= FIXED_ONE;
+      plane->dcdy *= 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.
+       */
+      plane->eo = 0;
+      if (plane->dcdx < 0) plane->eo -= plane->dcdx;
+      if (plane->dcdy > 0) plane->eo += plane->dcdy;
+
+      /* Calculate trivial accept offsets from the above.
+       */
+      plane->ei = plane->dcdy - plane->dcdx - plane->eo;
+
+      plane->step = line->step[i];
+
+      /* Fill in the inputs.step[][] arrays.
+       * We've manually unrolled some loops here.
+       */
+#define SETUP_STEP(j, x, y) \
+      line->step[i][j] = y * plane->dcdy - x * plane->dcdx                                     
+      
+      SETUP_STEP(0, 0, 0);
+      SETUP_STEP(1, 1, 0);
+      SETUP_STEP(2, 0, 1);
+      SETUP_STEP(3, 1, 1);
+
+      SETUP_STEP(4, 2, 0);
+      SETUP_STEP(5, 3, 0);
+      SETUP_STEP(6, 2, 1);
+      SETUP_STEP(7, 3, 1);
+
+      SETUP_STEP(8, 0, 2);
+      SETUP_STEP(9, 1, 2);
+      SETUP_STEP(10, 0, 3);
+      SETUP_STEP(11, 1, 3);
+
+      SETUP_STEP(12, 2, 2);
+      SETUP_STEP(13, 3, 2);
+      SETUP_STEP(14, 2, 3);
+      SETUP_STEP(15, 3, 3);
+#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 == 8) {
+      line->plane[4].step = step_scissor_maxx;
+      line->plane[4].dcdx = 1;
+      line->plane[4].dcdy = 0;
+      line->plane[4].c = maxx;
+      line->plane[4].ei = -1;
+      line->plane[4].eo = 0;
+
+      line->plane[5].step = step_scissor_miny;
+      line->plane[5].dcdx = 0;
+      line->plane[5].dcdy = 1;
+      line->plane[5].c = 1-miny;
+      line->plane[5].ei = 0;
+      line->plane[5].eo = 1;
+
+      line->plane[6].step = step_scissor_maxy;
+      line->plane[6].dcdx = 0;
+      line->plane[6].dcdy = -1;
+      line->plane[6].c = maxy;
+      line->plane[6].ei = -1;
+      line->plane[6].eo = 0;
+
+      line->plane[7].step = step_scissor_minx;
+      line->plane[7].dcdx = -1;
+      line->plane[7].dcdy = 0;
+      line->plane[7].c = 1-minx;
+      line->plane[7].ei = 0;
+      line->plane[7].eo = 1;
+   }
+
+
+   /*
+    * All fields of 'tri' are now set.  The remaining code here is
+    * concerned with binning.
+    */
+
+   /* Convert to tile coordinates, and inclusive ranges:
+    */
+   ix0 = minx / TILE_SIZE;
+   iy0 = miny / TILE_SIZE;
+   ix1 = (maxx-1) / TILE_SIZE;
+   iy1 = (maxy-1) / TILE_SIZE;
+
+   /*
+    * Clamp to framebuffer size
+    */
+   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 (iy0 == iy1 && ix0 == ix1)
+   {
+      /* Triangle is contained in a single tile:
+       */
+      lp_scene_bin_command( scene, ix0, iy0,
+                            lp_rast_tri_tab[nr_planes], 
+                            lp_rast_arg_triangle(line, (1<<nr_planes)-1) );
+   }
+   else
+   {
+      int c[8];
+      int ei[8];
+      int eo[8];
+      int xstep[8];
+      int ystep[8];
+      int x, y;
+      int is_blit = -1; /* undetermined */
+      
+      for (i = 0; i < nr_planes; i++) {
+         c[i] = (line->plane[i].c + 
+                 line->plane[i].dcdy * iy0 * TILE_SIZE - 
+                 line->plane[i].dcdx * ix0 * TILE_SIZE);
+
+         ei[i] = line->plane[i].ei << TILE_ORDER;
+         eo[i] = line->plane[i].eo << TILE_ORDER;
+         xstep[i] = -(line->plane[i].dcdx << TILE_ORDER);
+         ystep[i] = line->plane[i].dcdy << TILE_ORDER;
+      }
+
+
+
+      /* Test tile-sized blocks against the triangle.
+       * Discard blocks fully outside the tri.  If the block is fully
+       * contained inside the tri, bin an lp_rast_shade_tile command.
+       * Else, bin a lp_rast_triangle command.
+       */
+      for (y = iy0; y <= iy1; y++)
+      {
+         boolean in = FALSE;  /* are we inside the triangle? */
+         int cx[8];
+
+         for (i = 0; i < nr_planes; i++)
+            cx[i] = c[i];
+
+         for (x = ix0; x <= ix1; x++)
+         {
+            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);
+            }
+            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(line, partial) );
+
+               LP_COUNT(nr_partially_covered_64);
+            }
+            else {
+               /* triangle covers the whole tile- shade whole tile */
+               LP_COUNT(nr_fully_covered_64);
+               in = TRUE;
+               /* leverages on existing code in lp_setup_tri.c */ 
+               do_triangle_ccw_whole_tile(setup, scene, line, x, y,
+                                          opaque, &is_blit);
+            }
+
+            /* Iterate cx values across the region:
+             */
+            for (i = 0; i < nr_planes; i++)
+               cx[i] += xstep[i];
+         }
+      
+         /* Iterate c values down the region:
+          */
+         for (i = 0; i < nr_planes; i++)
+            c[i] += ystep[i];
+      }
+   }
+}
+
+
+void lp_setup_choose_line( struct lp_setup_context *setup ) 
+{ 
+   setup->line = lp_setup_line;
 }