Class: Shader

Inherits:
Object show all
Includes:
Gl
Defined in:
lib/ext/shader.rb

Constant Summary collapse

@@canvas_texture_id = 
nil

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(window, shader_filename) ⇒ Shader

Returns a new instance of Shader.



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# File 'lib/ext/shader.rb', line 10

def initialize(window, shader_filename)
  @window = window
  @shader_filename = shader_filename
  
  @program_id = nil
  @vertex_shader_id = nil
  @fragment_shader_id = nil
  
  create_canvas unless @@canvas_texture_id
  compile
end

Instance Attribute Details

#fragment_shader_id ⇒ Object (readonly)

Returns the value of attribute fragment_shader_id.



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# File 'lib/ext/shader.rb', line 6

def fragment_shader_id
  @fragment_shader_id
end

#program_id ⇒ Object (readonly)

Returns the value of attribute program_id.



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# File 'lib/ext/shader.rb', line 6

def program_id
  @program_id
end

#shader_filename ⇒ Object (readonly)

Returns the value of attribute shader_filename.



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# File 'lib/ext/shader.rb', line 5

def shader_filename
  @shader_filename
end

#vertex_shader_id ⇒ Object (readonly)

Returns the value of attribute vertex_shader_id.



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# File 'lib/ext/shader.rb', line 6

def vertex_shader_id
  @vertex_shader_id
end

#window ⇒ Object (readonly)

Returns the value of attribute window.



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# File 'lib/ext/shader.rb', line 5

def window
  @window
end

Instance Method Details

#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

#uniform(name, value) ⇒ Object Also known as: []= 



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# File 'lib/ext/shader.rb', line 58

def uniform(name, value)
  glUseProgram(@program_id)
  if value.is_a?(Float)
    glUniform1f(glGetUniformLocation(@program_id, name), value)
  elsif value.is_a?(Integer)
    glUniform1i(glGetUniformLocation(@program_id, name), value)
  else
    raise ArgumentError, "Uniform data type not supported"
  end
  glUseProgram(0)
end