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

static unsigned *image;
static int width, height, components;
static float incr = .01, dir = 1.0;
static float scale = 1.0, tscale = 1.0, trotx, troty;

static float transx = 1.0, transy, rotx, roty;
static int ox = -1, oy = -1;
static int mot = 0;
float *wrotx = &rotx, *wroty = &roty, *wscale = &scale;
#define PAN	1
#define ROT	2

void
pan(const int x, const int y) {
    transx +=  (x-ox)/5.;
    transy -= (y-oy)/5.;
    ox = x; oy = y;
    glutPostRedisplay();
}

void
rotate(const int x, const int y) {
    *wrotx += x-ox;
    if (*wrotx > 360.) *wrotx -= 360.;
    else if (*wrotx < -360.) *wrotx += 360.;
    *wroty += y-oy;
    if (*wroty > 360.) *wroty -= 360.;
    else if (*wroty < -360.) *wroty += 360.;
    ox = x; oy = y;
    glutPostRedisplay();
}

void
motion(int x, int y) {
    if (mot == PAN) pan(x, y);
    else if (mot == ROT) rotate(x,y);
}

void
mouse(int button, int state, int x, int y) {
    if(state == GLUT_DOWN) {
	switch(button) {
	case GLUT_LEFT_BUTTON:
	    mot = PAN;
	    motion(ox = x, oy = y);
	    break;
	case GLUT_MIDDLE_BUTTON:
	    mot = ROT;
	    motion(ox = x, oy = y);
	    break;
	case GLUT_RIGHT_BUTTON:
	    break;
	}
    } else if (state == GLUT_UP) {
	mot = 0;
    }
}

#define MAXMESH 64

float Ml[4*2*(MAXMESH+1)*2 * (MAXMESH+1)];

float N = 1.5;
float B = -1.5;

void
mesh1(float x0, float x1, float y0, float y1,
          float s0, float s1, float t0, float t1, float z, int nx, int ny)
{
    float y,x,s,t,dx,dy,ds,dt,vb[3],tb[2];
    float v;
    float *mp = Ml;
	
    dx = (x1-x0)/nx;
    dy = (y1-y0)/ny;
    ds = (s1-s0)/nx;
    dt = (t1-t0)/ny;
    y = y0;
    t = t0;
    vb[2] = z;
    while (y < y1) {
        x = x0;
        s = s0;
        while(x <= x1) {
            tb[0] = s; tb[1] = t;
            vb[0] = x; vb[1] = y;
            v = N*N - x*x - y*y;
            if (v < 0.0) v = 0.0;
            vb[2] = sqrt(v) + B;
            if (vb[2] < 0.) vb[2] = 0.0;
            *mp++ = tb[0];	
            *mp++ = tb[1];	
            mp += 2;
            *mp++ = vb[0];	
            *mp++ = vb[1];	
            *mp++ = vb[2];	
            mp++;
            tb[1] = t+dt;
            vb[1] = y+dy;
            v = N*N - x*x - (y+dy)*(y+dy);
            if (v < 0.0) v = 0.0;
            vb[2] = sqrt(v) + B;
            if (vb[2] < 0.) vb[2] = 0.0;
            *mp++ = tb[0];	
            *mp++ = tb[1];	
            mp += 2;
            *mp++ = vb[0];	
            *mp++ = vb[1];	
            *mp++ = vb[2];	
            mp++;
            x += dx;
            s += ds;
        }	
        y += dy;
        t += dt;
    }
}

void
drawmesh(int nx,int ny) {
    float *mp = Ml;
    int i,j;

    glColor4f(1,1,1,1);
    for (i = ny+1; i; i--) {
        glBegin(GL_TRIANGLE_STRIP);
        for (j = nx+1; j; j--) {
            glTexCoord2fv(mp);
            glVertex3fv(mp+4);
            glTexCoord2fv(mp+8);
            glVertex3fv(mp+12);	mp += 16;
        }
        glEnd();
    }
}

void
move(void) {
    if (N > 2.1 || N < 1.5)
	dir = -dir;
    N += incr*dir;
    mesh1(-1.5,1.5,-1.5,1.5,0.0,1.0,0.0,1.0,0.0,64,64);
    glutPostRedisplay();
}

void
alphaup(void) {
    incr += .01;
    if (incr > .1) incr = .1;
    glutPostRedisplay();
}

void
alphadown(void) {
    incr -= .01;
    if (incr < 0) incr = 0;
    glutPostRedisplay();
}

void
left(void) {
    *wscale -= .1;
}

void
right(void) {
    *wscale += .1;
}

void
wire(void) {
    static int wire_mode;
    if (wire_mode ^= 1)
	glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
    else
	glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
}

void
tfunc(void) {
    static state;
    if (state ^= 1) {
	wrotx = &trotx;
	wroty = &troty;
	wscale = &tscale;
    } else {
	wrotx = &rotx;
	wroty = &roty;
	wscale = &scale;
    }

}


void
help(void) {
    printf("'h'   - help\n");
    printf("'w'   - wire frame\n");
    printf("UP	  - faster\n");
    printf("DOWN  - slower\n");
}

void
init(char *filename) {
    if (filename) {
	image = read_texture(filename, &width, &height, &components);
	if (image == NULL) {
	    fprintf(stderr, "Error: Can't load image file \"%s\".\n",
		    filename);
	    exit(EXIT_FAILURE);
	} else {
	    printf("%d x %d image loaded\n", width, height);
	}
	if (components < 3 || components > 4) {
	    printf("must be RGB or RGBA image\n");
	    exit(EXIT_FAILURE);
	}
    } else {
	int i, j;
	components = 4; width = height = 128;
	image = (unsigned *) malloc(width*height*sizeof(unsigned));
	for (j = 0; j < height; j++)
	    for (i = 0; i < width; i++) {
		if (i & 16)
		    image[i+j*width] = 0xff;
		else
		    image[i+j*width] = 0xff00;
		if (j&16)
		    image[i+j*width] |= 0xff0000;
	    }

    }
    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexImage2D(GL_TEXTURE_2D, 0, components, width,
                 height, 0, GL_RGBA, GL_UNSIGNED_BYTE,
                 image);
    glEnable(GL_TEXTURE_2D);
    glMatrixMode(GL_TEXTURE);
    glLoadIdentity();
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(90.,1.,.1,10.);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glTranslatef(0.,0.,-1.5);
    glClearColor(.25, .25, .25, 0.);

}

void
display(void) {
    glClear(GL_COLOR_BUFFER_BIT);
    glMatrixMode(GL_TEXTURE);
    glPushMatrix();
    glTranslatef(.5f, .5f, .5f);
    glRotatef(trotx, 0.f, 0.f, 1.f);
    glScalef(tscale, tscale, tscale);
    glTranslatef(-.5f, -.5f, -.5f);
    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();
    glRotatef(rotx, 0.f, 0.f, 1.f);
    glScalef(scale, scale, scale);
    drawmesh(64,64);
    glPopMatrix();
    glMatrixMode(GL_TEXTURE);
    glPopMatrix();
    glMatrixMode(GL_MODELVIEW);
    glutSwapBuffers();
}

void
reshape(int w, int h) {
    glViewport(0, 0, w, h);
}

/*ARGSUSED1*/
void
key(unsigned char key, int x, int y) {
    switch(key) {
    case '\033':	exit(0); break;
    case 'h':		help(); break;
    case 't':		tfunc(); break;
    case 'w':		wire(); break;
    }
}

/*ARGSUSED1*/
void
special(int key, int x, int y) {
    switch(key) {
    case GLUT_KEY_UP:	alphaup(); break;
    case GLUT_KEY_DOWN:	alphadown(); break;
    case GLUT_KEY_LEFT:	left(); break;
    case GLUT_KEY_RIGHT:right(); break;
    }
}

int
main(int argc, char** argv) {
    glutInitWindowSize(256, 256);
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGBA|GLUT_DOUBLE);
    (void)glutCreateWindow("warp");
    init(argv[1]);
    glutKeyboardFunc(key);
    glutSpecialFunc(special);
    glutDisplayFunc(display);
    glutReshapeFunc(reshape);
    glutIdleFunc(move);
    glutMouseFunc(mouse);
    glutMotionFunc(motion);
    glutMainLoop();
    return 0;
}