opencl/motion-blur-linear.cl

   1 float4 get_pixel_color(const __global float4 *in_buf,
   2                        int     rect_width,
   3                        int     rect_height,
   4                        int     rect_x,
   5                        int     rect_y,
   6                        int     x,
   7                        int     y)
   8 {
   9     int ix = x - rect_x;
  10     int iy = y - rect_y;
  11
  12     ix = clamp(ix, 0, rect_width-1);
  13     iy = clamp(iy, 0, rect_height-1);
  14
  15     return in_buf[iy * rect_width + ix];
  16 }
  17
  18 __kernel void motion_blur_linear(const __global float4 *src_buf,
  19                                  int     src_width,
  20                                  int     src_height,
  21                                  int     src_x,
  22                                  int     src_y,
  23                                  __global float4 *dst_buf,
  24                                  int     dst_x,
  25                                  int     dst_y,
  26                                  int     num_steps,
  27                                  float   offset_x,
  28                                  float   offset_y)
  29 {
  30     int gidx = get_global_id(0);
  31     int gidy = get_global_id(1);
  32
  33     float4 sum = 0.0f;
  34     int px = gidx + dst_x;
  35     int py = gidy + dst_y;
  36
  37     for(int step = 0; step < num_steps; ++step)
  38     {
  39         float t = num_steps == 1 ? 0.0f :
  40             step / (float)(num_steps - 1) - 0.5f;
  41
  42         float xx = px + t * offset_x;
  43         float yy = py + t * offset_y;
  44
  45         int   ix = (int)floor(xx);
  46         int   iy = (int)floor(yy);
  47
  48         float dx = xx - floor(xx);
  49         float dy = yy - floor(yy);
  50
  51         float4 mixy0,mixy1,pix0,pix1,pix2,pix3;
  52
  53         pix0 = get_pixel_color(src_buf, src_width,
  54             src_height, src_x, src_y, ix,   iy);
  55         pix1 = get_pixel_color(src_buf, src_width,
  56             src_height, src_x, src_y, ix+1, iy);
  57         pix2 = get_pixel_color(src_buf, src_width,
  58             src_height, src_x, src_y, ix,   iy+1);
  59         pix3 = get_pixel_color(src_buf, src_width,
  60             src_height, src_x, src_y, ix+1, iy+1);
  61
  62         mixy0 = dy * (pix2 - pix0) + pix0;
  63         mixy1 = dy * (pix3 - pix1) + pix1;
  64
  65         sum  += dx * (mixy1 - mixy0) + mixy0;
  66     }
  67
  68     dst_buf[gidy * get_global_size(0) + gidx] =
  69         sum / (float4)(num_steps);
  70 }