csrDraw.h

   1 #include <time.h>
   2
   3 typedef struct csr_frag csr_frag;
   4
   5 struct csr_frag
   6 {
   7         u32 id; // Triangle index
   8         float qa, qb;   // Quantities
   9
  10         float depth;    // 'depth testing'
  11 };
  12
  13 void clear_depth( csr_frag fragments[], u32 x, u32 y )
  14 {
  15         for( u32 i = 0; i < x*y; i ++ )
  16         {
  17                 fragments[ i ].depth = INFINITY;
  18         }
  19 }
  20
  21 void simple_raster( csr_frag fragments[], u32 x, u32 y, v4f cam_bounds, vmf_vert tri[3], int id )
  22 {
  23         // Very simplified tracing algorithm
  24
  25         v2f bmin = { 0.f, 0.f };
  26         v2f bmax = { x, y };
  27
  28         v2_minv( tri[0].co, tri[1].co, bmin );
  29         v2_minv( tri[2].co, bmin, bmin );
  30
  31         v2_maxv( tri[0].co, tri[1].co, bmax );
  32         v2_maxv( tri[2].co, bmax, bmax );
  33
  34         float range_x = (cam_bounds[2]-cam_bounds[0])/(float)x;
  35         float range_y = (cam_bounds[3]-cam_bounds[1])/(float)y;
  36
  37         int start_x = csr_max( 0, floorf( (bmin[0]-cam_bounds[0])/range_x));
  38         int end_x =   csr_min( x, floorf( (bmax[0]-cam_bounds[0])/range_x ));
  39         int start_y = csr_max( 0, ceilf( (bmin[1]-cam_bounds[1])/range_y ));
  40         int end_y =   csr_min( y, ceilf( (bmax[1]-cam_bounds[1])/range_y ));
  41
  42         v3f trace_dir = { 0.f, 0.f, -1.f };
  43         v3f trace_origin = { 0.f, 0.f, 16385.f };
  44
  45         for( u32 py = start_y; py < end_y; py ++ )
  46         {
  47                 trace_origin[1] = csr_lerpf( cam_bounds[1], cam_bounds[3], (float)py/(float)y );
  48
  49                 for( u32 px = start_x; px < end_x; px ++ )
  50                 {
  51                         trace_origin[0] = csr_lerpf( cam_bounds[0], cam_bounds[2], (float)px/(float)x );
  52
  53                         csr_frag *frag = &fragments[ py*y + px ];
  54
  55                         float tqa = 0.f, tqb = 0.f;
  56                         float tdepth = csr_ray_tri( trace_origin, trace_dir, tri[0].co, tri[1].co, tri[2].co, &tqa, &tqb );
  57
  58                         if( tdepth < frag->depth )
  59                         {
  60                                 frag->depth = tdepth;
  61                                 frag->id = id;
  62                                 frag->qa = tqa;
  63                                 frag->qb = tqb;
  64                         }
  65                 }
  66         }
  67 }
  68
  69 // First pass 'fragmentize'
  70 void draw_buffers( csr_frag fragments[], u32 x, u32 y, v4f cam_bounds, vmf_vert *triangles, u32 triangle_count )
  71 {
  72         clock_t t;
  73    t = clock();
  74    printf("Timer starts\n");
  75
  76         clear_depth( fragments, x, y );
  77
  78         for( u32 i = 0; i < triangle_count; i ++ )
  79         {
  80                 vmf_vert *triangle = triangles + i*3;
  81                 simple_raster( fragments, x, y, cam_bounds, triangle, i );
  82         }
  83
  84         printf("Timer ends \n");
  85         t = clock() - t;
  86         double time_taken = ((double)t)/CLOCKS_PER_SEC; // calculate the elapsed time
  87         printf("Tracing took %f seconds to execute\n", time_taken);
  88 }