Source Code for Module toon.effects.chromakey

  1  #!/usr/bin/env python 
  2  """ 
  3  GLSL shaders with SDL, OpenGL texture and Python 
  4  """ 
  5  from pygame.locals import * 
  6  from OpenGL.GL import * 
  7  from OpenGL.error import NullFunctionError #TODO: port to all other shader. 
  8  from OpenGL.GLU import * 
  9  from rats.glsl import ShaderProgram 
 10  from rats.glsl import ShaderError 
 11  from toon import fx 
 12  from toon import optgroup 
 13   
 14  # globals 
 15  vert = """ 
 16  /** 
 17   * Vertex shader that does nothing 
 18   */ 
 19  // variables passed to the fragment shader 
 20  varying vec2 texcoord0; 
 21  varying vec2 texdim0; 
 22  void main() 
 23  { 
 24      gl_Position = ftransform(); 
 25      texcoord0 = vec2(gl_TextureMatrix[0] * gl_MultiTexCoord0); 
 26      texdim0 = vec2(abs(gl_TextureMatrix[0][0][0]), abs(gl_TextureMatrix[0][1][1])); 
 27  } 
 28  """ 
 29  frag = """ 
 30  /** 
 31   * Fragment shader for chroma-keying.  
 32   *  
 33   * (using a green or blue screen, or any background color) 
 34   *  
 35   * Main thing is, make sure the texcoord's arent  
 36   * normalized (so they are in the range of [0..w, 0..h] ) 
 37   *  
 38   * All params are vec3 in the range [0.0, 1.0] 
 39   *  
 40   * :param keying_color: The RGB keying color that will be made transparent. 
 41   * :param thresh: The distance from the color for a pixel to disappear. 
 42   *  
 43   * :author: Alexandre Quessy <alexandre@quessy.net> 2009 
 44   * :license: GNU Public License version 3 
 45   *  
 46   *  smoothstep with distance from target color 
 47   *  genType smoothStep(genType edge0, genType edge1, genType x); 
 48   *  The result will be zero if x <= edge0, 1  
 49   *  if x >= edge1 and performs smooth Hermite interpolation  
 50   *  between 0 and 1 when edge0 < x < edge1.  
 51   */ 
 52   
 53  // user-configurable variables (read-only) 
 54  uniform vec3 keying_color; 
 55  uniform float thresh; // [0, 1.732] 
 56  uniform float slope; // [0, 1] 
 57  // the texture 
 58  uniform sampler2DRect image; 
 59  // data passed from vertex shader: 
 60  varying vec2 texcoord0; 
 61  varying vec2 texdim0; 
 62  void main(void) 
 63  { 
 64      // sample from the texture  
 65      vec3 input_color = texture2DRect(image, texcoord0).rgb; 
 66      float d = abs(length(abs(keying_color.rgb - input_color.rgb))); 
 67      float edge0 = thresh * (1.0 - slope);  
 68      float alpha = smoothstep(edge0, thresh, d); 
 69      gl_FragColor = vec4(input_color, alpha);  
 70  } 
 71  """ 
 72   
 73 -class ChromaKeyOptions(optgroup.OptionsGroup): 
 74 -    def __init__(self): 
 75          self.target_color = [0.2, 0.0, 0.8] 
 76          self.thresh = 0.8 
 77          self.slope = 0.2 
 78          self.texture_id = 0 
 79   
 80 -class ChromaKeyEffect(fx.Effect): 
 81      """ 
 82      Chroma keying filter using GLSL. 
 83      """ 
 84 -    def __init__(self): 
 85          fx.Effect.__init__(self) 
 86          self.name = "chromakey" 
 87          self.program = None 
 88          self.options = ChromaKeyOptions() 
 89   
 90 -    def setup(self): 
 91          """ 
 92          Loads the plugin 
 93          """ 
 94          global vert 
 95          global frag 
 96          try: 
 97              self.program = ShaderProgram() 
 98              self.program.add_shader_text(GL_VERTEX_SHADER_ARB, vert) 
 99              self.program.add_shader_text(GL_FRAGMENT_SHADER_ARB, frag) 
100              self.program.linkShaders() 
101              self.loaded = True 
102          except NullFunctionError, e: 
103              print("Error: %s" % (e.message)) 
104              print("Disabling the chromakey effect") 
105          except ShaderError, e: 
106              print("Error: %s" % (e.message)) 
107              print("Disabling the chromakey effect") 
108          self.loaded = True 
109       
110 -    def pre_draw(self): 
111          if self.loaded and self.enabled: 
112              try: 
113                  self.program.enable() 
114              except Exception, e:  
115                  self.loaded = False 
116                  print(e.message) 
117              else: 
118                  self.program.glUniform1i("image", self.options.texture_id) 
119                  self.program.glUniform3f("keying_color", *self.options.target_color) 
120                  self.program.glUniform1f("thresh", self.options.thresh) 
121                  self.program.glUniform1f("slope", self.options.slope) 
122   
123 -    def post_draw(self): 
124          if self.loaded and self.enabled: 
125              try: 
126                  self.program.disable() 
127              except Exception, e:  
128                  self.loaded = False 
129                  print(e.message) 
130   
131 -def create_effect(): 
132      """ 
133      Factory for the effect in this module. 
134      """ 
135      return ChromaKeyEffect() 
136