Example OpenGL3.2 buffer/shader usage

gistfile1.c

/*
  Original: 1562391 by branan

  Updated to use GLFW so it works on Mac OS X Lion
*/
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#define GLFW_NO_GLU
#define GLFW_INCLUDE_GL3
#include <GL/glfw.h>

GLfloat vert_data[] = {
  -1.0, -1.0, 0.0,
  1.0, -1.0, 0.0,
  0.0, 1.0, 0.0,
};

GLfloat col_data[] = {
  1.0, 0.0, 0.0,
  0.0, 1.0, 0.0,
  0.0, 0.0, 1.0
};

#define POSITION_ATTRIB 0
#define COLOR_ATTRIB 1

const char* vert_shader =
  "\
#version 150\n\
\n\
in vec3 position;\n\
in vec3 color;\n\
out vec3 vcol;\n\
\n\
void main(void) { \n\
    vcol = color;\n\
    gl_Position = vec4(position, 1.0);\n\
}\n\
";

const char* frag_shader =
  "\
#version 150\n\
\n\
in vec3 vcol;\n\
out vec4 fcol;\n\
\n\
void main(void) { \n\
    fcol = vec4(vcol,1.0);\n\
}\n\
";

void init(void) {


  GLuint vao;
  GLuint bufs[2];
  glGenVertexArrays(1, &vao);
  glGenBuffers(2, bufs);

  glBindVertexArray(vao);
  glEnableVertexAttribArray(POSITION_ATTRIB);
  glEnableVertexAttribArray(COLOR_ATTRIB);

  glBindBuffer(GL_ARRAY_BUFFER, bufs[0]);
  glBufferData(GL_ARRAY_BUFFER, 3*3*sizeof(GLfloat), vert_data, GL_STATIC_DRAW);
  glVertexAttribPointer(POSITION_ATTRIB, 3, GL_FLOAT, GL_FALSE, 0, 0);

  glBindBuffer(GL_ARRAY_BUFFER, bufs[1]);
  glBufferData(GL_ARRAY_BUFFER, 3*3*sizeof(GLfloat), col_data, GL_STATIC_DRAW);
  glVertexAttribPointer(COLOR_ATTRIB, 3, GL_FLOAT, GL_FALSE, 0, 0);

  GLuint prog;
  GLuint vert;
  GLuint frag;

  prog = glCreateProgram();
  vert = glCreateShader(GL_VERTEX_SHADER);
  frag = glCreateShader(GL_FRAGMENT_SHADER);

  glShaderSource(vert, 1, &vert_shader, 0);
  glShaderSource(frag, 1, &frag_shader, 0);
  glCompileShader(vert);
  glCompileShader(frag);

  glAttachShader(prog, vert);
  glAttachShader(prog, frag);

  glBindAttribLocation(prog, POSITION_ATTRIB, "position");
  glBindAttribLocation(prog, COLOR_ATTRIB, "color");

  glLinkProgram(prog);
  glUseProgram(prog);
}

void render(void) {
  glClear(GL_COLOR_BUFFER_BIT);

  glDrawArrays(GL_TRIANGLES, 0, 3);

  glfwSwapBuffers();
}

int main(int argc, char** argv) {
  if (GL_TRUE != glfwInit())
  {
    fprintf(stderr, "ERROR: Unable to initialize GLFW\n");
  }

  glfwEnable(GLFW_AUTO_POLL_EVENTS); /* No explicit call to glfwPollEvents() */

  glfwOpenWindowHint(GLFW_WINDOW_NO_RESIZE, GL_TRUE);
  glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 3);
  glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, 2);
  glfwOpenWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); 
  glfwOpenWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);

  if (GL_TRUE != glfwOpenWindow(800, 600, 0, 0, 0, 0, 0, 0, GLFW_WINDOW))
  {
    fprintf(stderr, "ERROR: Unable to create the OpenGL context and associated window\n");
    exit(EXIT_FAILURE);
  }
  init();

  do {
    render();
  } while(glfwGetKey( GLFW_KEY_ESC ) != GLFW_PRESS &&
          glfwGetKey( 'Q' ) != GLFW_PRESS &&
          glfwGetWindowParam( GLFW_OPENED ) );
  glfwTerminate();
  exit(0);
}