Draw a triangle using GLSL and VBO in Rouge

gistfile1.rg

;; Rouge 0.0.15

(require "glut")
(require "opengl")

(def vertex-shader "
     attribute vec3 position;
     attribute vec4 color;
     varying vec4 vertex_color;
 
     void main(void) {
        vertex_color = color;
        gl_Position = vec4(position, 1.0);
     }")

(def fragment-shader "
     varying vec4 vertex_color;
 
     void main(void) {
        gl_FragColor = vertex_color;
     }")    

(GLUT/Init)
(GLUT/InitDisplayMode GLUT.GLUT_RGBA)
(GLUT/InitWindowSize 500 500)
(GLUT/CreateWindow "Draw a triangle using GLSL and VBO in Rouge")
 
(let [program (GL/CreateProgram)]
  (.each [{:type GL.VERTEX_SHADER :source vertex-shader}
          {:type GL.FRAGMENT_SHADER :source fragment-shader}] ;; We need doseq
    | [x] 
      (let [shader (GL/CreateShader (x :type))]
        (GL/ShaderSource shader (x :source))
        (GL/CompileShader shader)
        (GL/AttachShader program shader)
        (GL/DeleteShader shader)))
  (GL/LinkProgram program)
  (GL/UseProgram program)

  (.each [{:attr "position" :array [0.0 0.5 0.0, 0.577 -0.5 0.0, -0.577 -0.5 0.0]}
          {:attr "color" :array [1.0 0.0 0.0 1.0, 0.0 1.0 0.0 1.0, 0.0 0.0 1.0 1.0]}]
    | [x]
      (let [buffer (first (GL/GenBuffers 1))
            location (GL/GetAttribLocation program (x :attr))]
        (GL/BindBuffer GL.ARRAY_BUFFER buffer)
        (GL/BufferData GL.ARRAY_BUFFER (* (count (x :array)) 4) (.pack (x :array) "f*") GL.STATIC_DRAW)
        (GL/EnableVertexAttribArray location)
        (GL/VertexAttribPointer location (/ (count (x :array)) 3) GL.FLOAT false 0 0)
        (GL/BindBuffer GL.ARRAY_BUFFER 0))))

(GLUT/DisplayFunc
  (fn []
    (GL/Clear GL_COLOR_BUFFER_BIT)
    (GL/DrawArrays GL.TRIANGLES 0 3)
    (GL/Flush)
    (GLUT/SwapBuffers)))

(GLUT/ReshapeFunc
  (fn [w h]
    (GL/Viewport 0 0 w h)))

(GLUT/MainLoop)

I'm glad you like it :)