example.cpp

//
// On MacOSX compile with:
// g++ -framework OpenGL -framework GLUT -o example example.cpp
//

#include <stdlib.h>

#include <GLUT/glut.h>

GLuint program;

const char *vertexSource =
    "varying vec4 pos;\n"
    "void main() {\n"
    "    gl_Position = gl_ModelViewProjectionMatrix*gl_Vertex;\n"
    "    pos = gl_MultiTexCoord0;\n"
    "}\n";

const char *fragmentSource =
    "varying vec4 pos;\n"
    "void main() {\n"
    "    gl_FragColor = vec4(pos.x, pos.y, 0.5, 1.0);\n"
    "}\n";

void init(void) {    
   glClearColor (0.0, 0.0, 0.0, 0.0);
   glShadeModel(GL_FLAT);
   glEnable(GL_DEPTH_TEST);

   GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
   GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
   glShaderSource(vertexShader, 1, &vertexSource, NULL);
   glShaderSource(fragmentShader, 1, &fragmentSource, NULL);
   glCompileShader(vertexShader);
   glCompileShader(fragmentShader);

   program = glCreateProgram();
   glAttachShader(program, vertexShader);
   glAttachShader(program, fragmentShader);
   glLinkProgram(program);
}

void display(void) {
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
   glUseProgram(program);

   glBegin(GL_QUADS);
   glMultiTexCoord2f(GL_TEXTURE0, 0.0, 0.0); glVertex3f(-1.0, -1.0, 0.0);
   glMultiTexCoord2f(GL_TEXTURE0, 0.0, 1.0); glVertex3f(-1.0, 1.0, 0.0);
   glMultiTexCoord2f(GL_TEXTURE0, 1.0, 1.0); glVertex3f(1.0, 1.0, 0.0);
   glMultiTexCoord2f(GL_TEXTURE0, 1.0, 0.0); glVertex3f(1.0, -1.0, 0.0);

   glEnd();
   glFlush();
}

void reshape(int w, int h) {
   glViewport(0, 0, (GLsizei)w, (GLsizei)h);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   gluPerspective(45.0, (GLfloat)w/(GLfloat)h, 1.0, 30.0);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
   glTranslatef(0.0, 0.0, -3.6);
}

void keyboard (unsigned char key, int x, int y) {
   switch (key) {
      case 27:
         exit(0);
         break;
      default:
         break;
   }
}

int main(int argc, char** argv) {
   glutInit(&argc, argv);
   glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
   glutInitWindowSize(1280, 1280);
   glutInitWindowPosition(100, 100);
   glutCreateWindow(argv[0]);

   init();

   glutDisplayFunc(display);
   glutReshapeFunc(reshape);
   glutKeyboardFunc(keyboard);
   glutMainLoop();

   return 0; 
}