#include <GL/glut.h>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <string.h>

#define WINDSIZEX 100
#define WINDSIZEY 100

#define SIZEW 4
#define SIZEH 4

static GLfloat pricol[] = {0.4, 0.2, 0.6, 0.8};//{0.3, 0.5, 0.7, 0.9 };

// Draw function used by many test casses
static void Draw()
{
        glBegin(GL_QUADS);
        glVertex2i(0,0);
        glVertex2i(0,SIZEH);
        glVertex2i(SIZEW, SIZEH);
        glVertex2i(SIZEW,0);
        glEnd();
}


void init(void)
{
    glClearColor (1,1,1,1);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glDisable (GL_DITHER);
}

static void test(void)
{    
   GLfloat *buf;
   char cmd1[1024] = "!!ARBfp1.0\nPARAM const1 = {0.1, 0.4,-0.6, 0.8};\n ATTRIB pricol = fragment.color;\nOUTPUT outcolor = result.color;\n MOV outcolor, {0.2, 0.1, 0.4, 0.7};\nKIL +const1;\nMOV outcolor, const1;\n\nEND\0";
   //char cmd1[1024] = "!!ARBfp1.0\nATTRIB color2 = fragment.color.secondary;\nOUTPUT outcolor = result.color;\nABS outcolor,-color2;\n\nEND\0";
   GLuint programName;

   glColor4fv(pricol);

   glGenProgramsARB(1, &programName);
   // bind a program to the name
   glBindProgramARB(GL_FRAGMENT_PROGRAM_ARB, programName);
   ///////////////////////////////////////
    glProgramStringARB(GL_FRAGMENT_PROGRAM_ARB, GL_PROGRAM_FORMAT_ASCII_ARB,
                           (GLint) strlen(cmd1), cmd1);
   if(glGetError() == GL_INVALID_OPERATION) {
         printf("\nError loading program: check the error\n%s",
                  glGetString(GL_PROGRAM_ERROR_STRING_ARB));
         exit(1);
    }
    glEnable(GL_FRAGMENT_PROGRAM_ARB);


   glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
   Draw();
   ///////////////////////////////////////

   buf = (GLfloat *)malloc(SIZEW * SIZEH *sizeof(GLfloat) * 4);
   glReadPixels(0, 0, SIZEW, SIZEH, GL_RGBA, GL_FLOAT, buf);
   printf("draw pixel at (0, 0): %f %f %f %f\n", buf[0], buf[1], buf[2], buf[3]);
}

void display(void)
{
    glViewport(0, 0, WINDSIZEX, WINDSIZEY);
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
    gluOrtho2D(0, WINDSIZEX, 0, WINDSIZEY);
        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();

    test();
}

int main(int argc, char** argv)
{
   glutInit(&argc, argv);
   glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
   glutInitWindowSize(WINDSIZEX, WINDSIZEY);
   glutInitWindowPosition(100, 100);
   glutCreateWindow(argv[0]);
   init();
   glutDisplayFunc(display);
   glutMainLoop();
   return 0; 
}