git.sesse.net Git - movit/blob - blur_effect.cpp

   1 #define GL_GLEXT_PROTOTYPES 1
   2
   3 #include <math.h>
   4 #include <GL/gl.h>
   5 #include <GL/glext.h>
   6
   7 #include "blur_effect.h"
   8 #include "util.h"
   9
  10 BlurEffect::BlurEffect()
  11         : radius(3.0f)
  12 {
  13         register_float("radius", (float *)&radius);
  14 }
  15
  16 std::string BlurEffect::output_fragment_shader()
  17 {
  18         return read_file("blur_effect.frag");
  19 }
  20
  21 void BlurEffect::set_uniforms(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num)
  22 {
  23         Effect::set_uniforms(glsl_program_num, prefix, sampler_num);
  24
  25         // We only have 15 taps to work with, and we want that to reach out to about 2.5*sigma.
  26         // Bump up the mipmap levels (giving us box blurs) until we have what we need.
  27         unsigned base_mipmap_level = 0;
  28         float adjusted_radius = radius;
  29         float pixel_size = 1.0f;
  30         while (adjusted_radius * 2.5f > 7.0f) {
  31                 ++base_mipmap_level;
  32                 adjusted_radius *= 0.5f;
  33                 pixel_size *= 2.0f;
  34         }
  35
  36         glActiveTexture(GL_TEXTURE0);
  37         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, base_mipmap_level);
  38         check_error();
  39
  40         set_uniform_float(glsl_program_num, prefix, "pixel_offset", pixel_size / 1280.0f);  // FIXME
  41
  42         // Simple Gaussian weights for now.
  43         float weight[15], total = 0.0f;
  44         for (unsigned i = 0; i < 15; ++i) {
  45                 float z = (i - 7.0f) / adjusted_radius;
  46                 weight[i] = exp(-(z*z));
  47                 total += weight[i];
  48         }
  49         printf("[mip level %d] ", base_mipmap_level);
  50         for (unsigned i = 0; i < 15; ++i) {
  51                 weight[i] /= total;
  52                 printf("%f ", weight[i]);
  53         }
  54         printf("\n");
  55         set_uniform_float_array(glsl_program_num, prefix, "weight", weight, 15);
  56 }