Method: Shader#apply

Defined in:
lib/ext/shader.rb

#apply ⇒ Object 



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# File 'lib/ext/shader.rb', line 22

def apply
  @window.gl do
    # copy frame buffer to canvas texture
    glBindTexture(GL_TEXTURE_2D, @@canvas_texture_id)
    glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 0, 0, @window.width, @window.height, 0)
    
    # apply shader
    glUseProgram(@program_id)
    
    # clear screen
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
    glColor4f(1.0, 1.0, 1.0, 1.0)
    glMatrixMode(GL_PROJECTION)
    glPushMatrix
    glLoadIdentity
    glViewport(0, 0, @window.width, @window.height)
    glOrtho(0, @window.width, @window.height, 0, -1, 1)
    
    # draw processed canvas texture over the screen
    glBindTexture(GL_TEXTURE_2D, @@canvas_texture_id)
    
    glBegin(GL_QUADS)
    glTexCoord2f(0.0, 1.0); glVertex2f(0.0,           0.0)
    glTexCoord2f(1.0, 1.0); glVertex2f(@window.width, 0.0)
    glTexCoord2f(1.0, 0.0); glVertex2f(@window.width, @window.height)
    glTexCoord2f(0.0, 0.0); glVertex2f(0.0,           @window.height)
    glEnd
    
    # done, disable shader
    glUseProgram(0)
    
    # and out
    glPopMatrix
  end
end