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/**
** sipp - SImple Polygon Processor
**
** A general 3d graphic package
**
** Copyright Equivalent Software HB 1992
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 1, or any later version.
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU General Public License for more details.
** You can receive a copy of the GNU General Public License from the
** Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
**/
/**
** ellipsoid.c - Creating ellipsiods and spheres as sipp objects.
**/
#include <xalloca.h>
#include <math.h>
#include <sipp.h>
#include <primitives.h>
Object *
sipp_ellipsoid(x_rad, y_rad, z_rad, res, surface, shader, texture)
double x_rad;
double y_rad;
double z_rad;
int res;
void *surface;
Shader *shader;
int texture;
{
int i, j;
double factor;
double factor1;
double factor2;
double zradprim;
double zradprim1;
double zradprim2;
double *x_arr;
double *y_arr;
double *u_arr;
double *v1, *v2;
Object *ellipsoid;
bool old_user_refs;
/* Odd resolutions make ugly spheres since the poles will be */
/* different in size. */
if (res & 1) {
res++;
}
/* Create two arrays with the coordinates of the points */
/* around the perimeter at Z = 0 */
x_arr = (double *) alloca((res + 1) * sizeof(double));
y_arr = (double *) alloca((res + 1) * sizeof(double));
u_arr = (double *) alloca((res + 1) * sizeof(double));
if (texture == SPHERICAL || texture == NATURAL) {
v1 = (double *) alloca((res + 1) * sizeof(double));
v2 = (double *) alloca((res + 1) * sizeof(double));
}
for (i = 0; i <= res; i++) {
x_arr[i] = x_rad * cos(i * 2.0 * M_PI / res);
y_arr[i] = y_rad * sin(i * 2.0 * M_PI / res);
u_arr[i] = (double)i / (double)res;
}
/* Create the top pole */
factor = sin(2.0 * M_PI / res);
zradprim = z_rad * cos(2.0 * M_PI / res);
if (texture == SPHERICAL || texture == NATURAL) {
for (i = 0; i < res; i++) {
v2[i] = (atan(zradprim
/ sqrt(factor * factor * (x_arr[i] * x_arr[i]
+ y_arr[i] * y_arr[i])))
/ M_PI + 0.5);
}
v2[i] = v2[0];
}
for (i = 0; i < res; i++) {
switch (texture) {
case NATURAL:
case SPHERICAL:
vertex_tx_push(x_arr[i] * factor, y_arr[i] * factor, zradprim,
u_arr[i], v2[i], 0.0);
vertex_tx_push(factor * x_arr[i + 1], factor * y_arr[i + 1],
zradprim,
u_arr[i + 1], v2[i + 1], 0.0);
vertex_tx_push(0.0, 0.0, z_rad, u_arr[i + 1], 1.0, 0.0);
vertex_tx_push(0.0, 0.0, z_rad, u_arr[i], 1.0, 0.0);
break;
case CYLINDRICAL:
vertex_tx_push(x_arr[i] * factor, y_arr[i] * factor, zradprim,
u_arr[i], zradprim / (2.0 * z_rad) + 0.5, 0.0);
vertex_tx_push(factor * x_arr[i + 1], factor * y_arr[i + 1],
zradprim,
u_arr[i + 1], zradprim / (2.0 * z_rad) + 0.5, 0.0);
vertex_tx_push(0.0, 0.0, z_rad, u_arr[i + 1], 1.0, 0.0);
vertex_tx_push(0.0, 0.0, z_rad, u_arr[i], 1.0, 0.0);
break;
case WORLD:
default:
vertex_tx_push(x_arr[i] * factor, y_arr[i] * factor, zradprim,
x_arr[i] * factor, y_arr[i] * factor, zradprim);
vertex_tx_push(factor * x_arr[i + 1],
factor * y_arr[i + 1],
zradprim,
factor * x_arr[i + 1],
factor * y_arr[i + 1],
zradprim);
vertex_tx_push(0.0, 0.0, z_rad, 0.0, 0.0, z_rad);
break;
}
polygon_push();
}
/* Create the surface between the poles. */
factor2 = factor;
zradprim2 = zradprim;
for (j = 1; j < res / 2 - 1; j++) {
factor1 = factor2;
factor2 = sin((j + 1) * M_PI / (res / 2));
zradprim1 = zradprim2;
zradprim2 = z_rad * cos((j + 1) * M_PI / (res / 2));
if (texture == SPHERICAL || texture == NATURAL) {
for (i = 0; i<=res; i++) v1[i] = v2[i];
for (i = 0; i < res; i++) {
v2[i] = (atan(zradprim2
/ sqrt(factor2 * factor2
* (x_arr[i] * x_arr[i]
+ y_arr[i] * y_arr[i])))
/ M_PI + 0.5);
}
v2[i] = v2[0];
}
for (i = 0; i < res; i++) {
switch (texture) {
case NATURAL:
case SPHERICAL:
vertex_tx_push(factor1 * x_arr[i], factor1 * y_arr[i],
zradprim1,
u_arr[i], v1[i], 0.0);
vertex_tx_push(factor2 * x_arr[i], factor2 * y_arr[i],
zradprim2,
u_arr[i], v2[i], 0.0);
vertex_tx_push(factor2 * x_arr[i + 1], factor2 * y_arr[i + 1],
zradprim2,
u_arr[i + 1], v2[i + 1], 0.0);
vertex_tx_push(factor1 * x_arr[i + 1], factor1 * y_arr[i + 1],
zradprim1,
u_arr[i + 1], v1[i + 1], 0.0);
break;
case CYLINDRICAL:
vertex_tx_push(factor1 * x_arr[i], factor1 * y_arr[i],
zradprim1,
u_arr[i], zradprim1 / (2.0 * z_rad) + 0.5, 0.0);
vertex_tx_push(factor2 * x_arr[i], factor2 * y_arr[i],
zradprim2,
u_arr[i], zradprim2 / (2.0 * z_rad) + 0.5, 0.0);
vertex_tx_push(factor2 * x_arr[i + 1], factor2 * y_arr[i + 1],
zradprim2,
u_arr[i + 1], zradprim2 / (2.0 * z_rad) + 0.5,
0.0);
vertex_tx_push(factor1 * x_arr[i + 1], factor1 * y_arr[i + 1],
zradprim1,
u_arr[i + 1], zradprim1 / (2.0 * z_rad) + 0.5,
0.0);
break;
case WORLD:
default:
vertex_tx_push(factor1 * x_arr[i], factor1 * y_arr[i],
zradprim1,
factor1 * x_arr[i], factor1 * y_arr[i],
zradprim1);
vertex_tx_push(factor2 * x_arr[i], factor2 * y_arr[i],
zradprim2,
factor2 * x_arr[i], factor2 * y_arr[i],
zradprim2);
vertex_tx_push(factor2 * x_arr[i + 1], factor2 * y_arr[i + 1],
zradprim2,
factor2 * x_arr[i + 1], factor2 * y_arr[i + 1],
zradprim2);
vertex_tx_push(factor1 * x_arr[i + 1], factor1 * y_arr[i + 1],
zradprim1,
factor1 * x_arr[i + 1], factor1 * y_arr[i + 1],
zradprim1);
}
polygon_push();
}
}
/* Create the bottom pole */
factor = sin(2.0 * M_PI / res);
zradprim = -z_rad * cos(2.0 * M_PI / res);
for (i = 0; i < res; i++) {
switch (texture) {
case NATURAL:
case SPHERICAL:
vertex_tx_push(factor * x_arr[i + 1], factor * y_arr[i + 1],
zradprim,
u_arr[i + 1], v2[i + 1], 0.0);
vertex_tx_push(x_arr[i] * factor, y_arr[i] * factor, zradprim,
u_arr[i], v2[i], 0.0);
vertex_tx_push(0.0, 0.0, -z_rad,
u_arr[i], 0.0, 0.0);
vertex_tx_push(0.0, 0.0, -z_rad,
u_arr[i + 1], 0.0, 0.0);
break;
case CYLINDRICAL:
vertex_tx_push(factor * x_arr[i + 1], factor * y_arr[i + 1],
zradprim,
u_arr[i + 1], zradprim / (2.0 * z_rad) + 0.5, 0.0);
vertex_tx_push(x_arr[i] * factor, y_arr[i] * factor, zradprim,
u_arr[i], zradprim / (2.0 * z_rad) + 0.5, 0.0);
vertex_tx_push(0.0, 0.0, -z_rad,
u_arr[i], 0.0, 0.0);
vertex_tx_push(0.0, 0.0, -z_rad,
u_arr[i + 1], 0.0, 0.0);
break;
case WORLD:
default:
vertex_tx_push(x_arr[i + 1] * factor, y_arr[i + 1] * factor,
zradprim,
x_arr[i + 1] * factor, y_arr[i + 1] * factor,
zradprim);
vertex_tx_push(x_arr[i] * factor, y_arr[i] * factor, zradprim,
x_arr[i] * factor, y_arr[i] * factor, zradprim);
vertex_tx_push(0.0, 0.0, -z_rad, 0.0, 0.0, -z_rad);
break;
}
polygon_push();
}
ellipsoid = object_create();
old_user_refs = sipp_user_refcount (FALSE);
object_add_surface(ellipsoid, surface_create(surface, shader));
sipp_user_refcount (old_user_refs);
return ellipsoid;
}
Object *
sipp_sphere(radius, res, surface, shader, texture)
double radius;
int res;
void *surface;
Shader *shader;
int texture;
{
return sipp_ellipsoid(radius, radius, radius, res, surface, shader,
texture);
}
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