/*
* Copyright (c) 2002-2008 LWJGL Project
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*
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*
* * Redistributions in binary form must reproduce the above copyright
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* documentation and/or other materials provided with the distribution.
*
* * Neither the name of 'LWJGL' nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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*/
package org.lwjgl.util.glu;
import static org.lwjgl.opengl.GL11.*;
import static org.lwjgl.util.glu.GLU.*;
/**
* Sphere.java
*
*
* Created 23-dec-2003
* @author Erik Duijs
*/
public class Sphere extends Quadric {
/**
* Constructor
*/
public Sphere() {
super();
}
/**
* draws a sphere of the given radius centered around the origin.
* The sphere is subdivided around the z axis into slices and along the z axis
* into stacks (similar to lines of longitude and latitude).
*
* If the orientation is set to GLU.OUTSIDE (with glu.quadricOrientation), then
* any normals generated point away from the center of the sphere. Otherwise,
* they point toward the center of the sphere.
* If texturing is turned on (with glu.quadricTexture), then texture
* coordinates are generated so that t ranges from 0.0 at z=-radius to 1.0 at
* z=radius (t increases linearly along longitudinal lines), and s ranges from
* 0.0 at the +y axis, to 0.25 at the +x axis, to 0.5 at the -y axis, to 0.75
* at the -x axis, and back to 1.0 at the +y axis.
*/
public void draw(float radius, int slices, int stacks) {
// TODO
float rho, drho, theta, dtheta;
float x, y, z;
float s, t, ds, dt;
int i, j, imin, imax;
boolean normals;
float nsign;
normals = super.normals != GLU_NONE;
if (super.orientation == GLU_INSIDE) {
nsign = -1.0f;
} else {
nsign = 1.0f;
}
drho = PI / stacks;
dtheta = 2.0f * PI / slices;
if (super.drawStyle == GLU_FILL) {
if (!super.textureFlag) {
// draw +Z end as a triangle fan
glBegin(GL_TRIANGLE_FAN);
glNormal3f(0.0f, 0.0f, 1.0f);
glVertex3f(0.0f, 0.0f, nsign * radius);
for (j = 0; j <= slices; j++) {
theta = (j == slices) ? 0.0f : j * dtheta;
x = -sin(theta) * sin(drho);
y = cos(theta) * sin(drho);
z = nsign * cos(drho);
if (normals) {
glNormal3f(x * nsign, y * nsign, z * nsign);
}
glVertex3f(x * radius, y * radius, z * radius);
}
glEnd();
}
ds = 1.0f / slices;
dt = 1.0f / stacks;
t = 1.0f; // because loop now runs from 0
if (super.textureFlag) {
imin = 0;
imax = stacks;
} else {
imin = 1;
imax = stacks - 1;
}
// draw intermediate stacks as quad strips
for (i = imin; i < imax; i++) {
rho = i * drho;
glBegin(GL_QUAD_STRIP);
s = 0.0f;
for (j = 0; j <= slices; j++) {
theta = (j == slices) ? 0.0f : j * dtheta;
x = -sin(theta) * sin(rho);
y = cos(theta) * sin(rho);
z = nsign * cos(rho);
if (normals) {
glNormal3f(x * nsign, y * nsign, z * nsign);
}
TXTR_COORD(s, t);
glVertex3f(x * radius, y * radius, z * radius);
x = -sin(theta) * sin(rho + drho);
y = cos(theta) * sin(rho + drho);
z = nsign * cos(rho + drho);
if (normals) {
glNormal3f(x * nsign, y * nsign, z * nsign);
}
TXTR_COORD(s, t - dt);
s += ds;
glVertex3f(x * radius, y * radius, z * radius);
}
glEnd();
t -= dt;
}
if (!super.textureFlag) {
// draw -Z end as a triangle fan
glBegin(GL_TRIANGLE_FAN);
glNormal3f(0.0f, 0.0f, -1.0f);
glVertex3f(0.0f, 0.0f, -radius * nsign);
rho = PI - drho;
s = 1.0f;
for (j = slices; j >= 0; j--) {
theta = (j == slices) ? 0.0f : j * dtheta;
x = -sin(theta) * sin(rho);
y = cos(theta) * sin(rho);
z = nsign * cos(rho);
if (normals)
glNormal3f(x * nsign, y * nsign, z * nsign);
s -= ds;
glVertex3f(x * radius, y * radius, z * radius);
}
glEnd();
}
} else if (
super.drawStyle == GLU_LINE
|| super.drawStyle == GLU_SILHOUETTE) {
// draw stack lines
for (i = 1;
i < stacks;
i++) { // stack line at i==stacks-1 was missing here
rho = i * drho;
glBegin(GL_LINE_LOOP);
for (j = 0; j < slices; j++) {
theta = j * dtheta;
x = cos(theta) * sin(rho);
y = sin(theta) * sin(rho);
z = cos(rho);
if (normals)
glNormal3f(x * nsign, y * nsign, z * nsign);
glVertex3f(x * radius, y * radius, z * radius);
}
glEnd();
}
// draw slice lines
for (j = 0; j < slices; j++) {
theta = j * dtheta;
glBegin(GL_LINE_STRIP);
for (i = 0; i <= stacks; i++) {
rho = i * drho;
x = cos(theta) * sin(rho);
y = sin(theta) * sin(rho);
z = cos(rho);
if (normals)
glNormal3f(x * nsign, y * nsign, z * nsign);
glVertex3f(x * radius, y * radius, z * radius);
}
glEnd();
}
} else if (super.drawStyle == GLU_POINT) {
// top and bottom-most points
glBegin(GL_POINTS);
if (normals)
glNormal3f(0.0f, 0.0f, nsign);
glVertex3f(0.0f, 0.0f, radius);
if (normals)
glNormal3f(0.0f, 0.0f, -nsign);
glVertex3f(0.0f, 0.0f, -radius);
// loop over stacks
for (i = 1; i < stacks - 1; i++) {
rho = i * drho;
for (j = 0; j < slices; j++) {
theta = j * dtheta;
x = cos(theta) * sin(rho);
y = sin(theta) * sin(rho);
z = cos(rho);
if (normals)
glNormal3f(x * nsign, y * nsign, z * nsign);
glVertex3f(x * radius, y * radius, z * radius);
}
}
glEnd();
}
}
}