/* Simplest demo of reading in an image and texture-mapping it onto
   something; in this case, a cube.

   Scott D. Anderson
   Fall 2003 
*/

#include <math.h>
#include <GL/glut.h>
#include <stdio.h>                // for printf
#include <stdlib.h>                // for exit
#include <tw.h>

char* filename;

void texinit() {
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

    twTex2D(filename,true);
}    

int obj=0;                        // the current kind of object

void display() {
    twDisplayInit();
    twCamera();

    glPushAttrib(GL_ALL_ATTRIB_BITS);
    glEnable(GL_TEXTURE_2D);

    switch(obj) {
    case 0:
        // this is a *square*, so the aspect ratio may not match the texture's AR
        glBegin(GL_QUADS);
        glTexCoord2f(0,1); glVertex3f( -1,-1,0); 
        glTexCoord2f(1,1); glVertex3f(  1,-1,0); 
        glTexCoord2f(1,0); glVertex3f(  1, 1,0); 
        glTexCoord2f(0,0); glVertex3f( -1, 1,0); 
        glEnd();
        break;
    case 1: glutSolidTeapot(1); break;
    case 2:
        {
            GLfloat sgenparams1[] = {0,0,0.5,0.5};
            GLfloat sgenparams2[] = {0,0.5,0,0.5};

            glEnable(GL_TEXTURE_GEN_S);
            glEnable(GL_TEXTURE_GEN_T);
            glTexGeni(GL_S,GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);
            glTexGenfv(GL_S,GL_OBJECT_PLANE,sgenparams1);
            glTexGeni(GL_T,GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);
            glTexGenfv(GL_T,GL_OBJECT_PLANE,sgenparams2);
            glPushMatrix();
            glutSolidCube(2);
            glPopMatrix();
            glDisable(GL_TEXTURE_GEN_S);
            glDisable(GL_TEXTURE_GEN_T);
            break;
        }
    case 3:
        {
            GLfloat sgenparams1[] = {1,0,0,0};
            GLfloat sgenparams2[] = {0,1,1,0};

            glEnable(GL_TEXTURE_GEN_S);
            glEnable(GL_TEXTURE_GEN_T);
            glTexGeni(GL_S,GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);
            glTexGenfv(GL_S,GL_OBJECT_PLANE,sgenparams1);
            glTexGeni(GL_T,GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);
            glTexGenfv(GL_T,GL_OBJECT_PLANE,sgenparams2);
            twSolidCylinder(1,0.5,1,20,20);
            glDisable(GL_TEXTURE_GEN_S);
            glDisable(GL_TEXTURE_GEN_T);
            break;
        }
    }

    glPopAttrib();
    glFlush();
    glutSwapBuffers();
}

void newObj(unsigned char, int, int) {
    obj = (obj+1)%4;
    glutPostRedisplay();
}

int main(int argc, char **argv) {
    if(argc < 2) {
        printf("Usage: %s ppm-image-file-name\n",argv[0]);
        exit(0);
    } else {
        filename=argv[1];
    }
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    twInitWindowSize(500, 500);
    glutCreateWindow(argv[0]);
    glutDisplayFunc(display);
    twBoundingBox(-1,+1,-1,+1,-1,1);
    twMainInit();
    twKeyCallback('o',newObj,"try a different object");
    texinit();
    glutMainLoop();                   
}