#include "pch.c"
#pragma hdrstop
#include <math.h>

static GLfloat ctrlpoints[4][4][3] = {
    {{ -1.5, -1.5, 4.0}, { -0.5, -1.5, 2.0}, 
	{0.5, -1.5, -1.0}, {1.5, -1.5, 2.0}}, 
    {{ -1.5, -0.5, 1.0}, { -0.5, -0.5, 3.0}, 
	{0.5, -0.5, 0.0}, {1.5, -0.5, -1.0}}, 
    {{ -1.5, 0.5, 4.0}, { -0.5, 0.5, 0.0}, 
	{0.5, 0.5, 3.0}, {1.5, 0.5, 4.0}}, 
    {{ -1.5, 1.5, -2.0}, { -0.5, 1.5, -2.0}, 
	{0.5, 1.5, 0.0}, {1.5, 1.5, -1.0}}
};

static GLfloat texpts[2][2][2] = {{{0.0, 0.0}, {0.0, 1.0}}, 
			{{1.0, 0.0}, {1.0, 1.0}}};

static void display(void)
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glColor3f(1.0, 1.0, 1.0);
    glEvalMesh2(GL_FILL, 0, 20, 0, 20);
    glFlush();
}

#define	imageWidth 64
#define	imageHeight 64
GLubyte image[3*imageWidth*imageHeight];

static void makeImage(void)
{
    int i, j;
    float ti, tj;
    
    for (i = 0; i < imageWidth; i++) {
	ti = 2.0*3.14159265*i/imageWidth;
	for (j = 0; j < imageHeight; j++) {
	    tj = 2.0*3.14159265*j/imageHeight;

	    image[3*(imageHeight*i+j)] = (GLubyte) 127*(1.0+sin(ti));
	    image[3*(imageHeight*i+j)+1] = (GLubyte) 127*(1.0+cos(2*tj));
	    image[3*(imageHeight*i+j)+2] = (GLubyte) 127*(1.0+cos(ti+tj));
	}
    }
}

static void myinit(void)
{
    glMap2f(GL_MAP2_VERTEX_3, 0, 1, 3, 4,
	    0, 1, 12, 4, &ctrlpoints[0][0][0]);
    glMap2f(GL_MAP2_TEXTURE_COORD_2, 0, 1, 2, 2, 
	    0, 1, 4, 2, &texpts[0][0][0]);
    glEnable(GL_MAP2_TEXTURE_COORD_2);
    glEnable(GL_MAP2_VERTEX_3);
    glMapGrid2f(20, 0.0, 1.0, 20, 0.0, 1.0);
    makeImage();
    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);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexImage2D(GL_TEXTURE_2D, 0, 3, imageWidth, imageHeight, 0,
		 GL_RGB, GL_UNSIGNED_BYTE, image);
    glEnable(GL_TEXTURE_2D);
    glEnable(GL_DEPTH_TEST);
    glEnable(GL_NORMALIZE);
    glShadeModel (GL_FLAT);
}

static void myReshape(GLsizei w, GLsizei h)
{
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    if (w <= h)
	glOrtho(-4.0, 4.0, -4.0*(GLfloat)h/(GLfloat)w, 
	    4.0*(GLfloat)h/(GLfloat)w, -4.0, 4.0);
    else
	glOrtho(-4.0*(GLfloat)w/(GLfloat)h, 
	    4.0*(GLfloat)w/(GLfloat)h, -4.0, 4.0, -4.0, 4.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glRotatef(85.0, 1.0, 1.0, 1.0);
}

#define WIDTH 300
#define HEIGHT 300

static void OglBounds(int *w, int *h)
{
    *w = WIDTH;
    *h = HEIGHT;
}

static void OglDraw(int w, int h)
{
    myinit();
    myReshape(w, h);
    display();
}

OglModule oglmod_texsurf =
{
    "texsurf",
    NULL,
    OglBounds,
    NULL,
    OglDraw
};