1 /*
2 * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25 package nbody;
26
27 import wrap.Wrap;
28 import wrap.glwrap.GLTexture;
29 import wrap.glwrap.GLWindow;
30
31 import java.io.IOException;
32 import java.lang.foreign.Arena;
33 import java.util.stream.IntStream;
34
35 import static opengl.opengl_h.GLUT_DEPTH;
36 import static opengl.opengl_h.GLUT_DOUBLE;
37 import static opengl.opengl_h.GLUT_RGB;
38 import static opengl.opengl_h.GL_COLOR_BUFFER_BIT;
39 import static opengl.opengl_h.GL_DEPTH_BUFFER_BIT;
40 import static opengl.opengl_h.GL_MODELVIEW;
41 import static opengl.opengl_h.GL_TEXTURE_2D;
42 import static opengl.opengl_h.glBindTexture;
43 import static opengl.opengl_h.glClear;
44 import static opengl.opengl_h.glClearColor;
45 import static opengl.opengl_h.glColor3f;
46 import static opengl.opengl_h.glDisable;
47 import static opengl.opengl_h.glEnable;
48 import static opengl.opengl_h.glMatrixMode;
49 import static opengl.opengl_h.glRasterPos2f;
50 import static opengl.opengl_h.glScalef;
51 import static opengl.opengl_h.glTexCoord2f;
52 import static opengl.opengl_h.glVertex3f;
53 import static opengl.opengl_h.glutBitmapCharacter;
54 import static opengl.opengl_h.glutBitmapTimesRoman24$segment;
55 import static opengl.opengl_h.glutSwapBuffers;
56
57
58 public abstract class NBodyGLWindow extends GLWindow {
59 protected final float delT = .1f;
60
61 protected final float espSqr = 0.1f;
62
63 protected final float mass = .5f;
64
65 protected final GLTexture particle;
66 protected final Wrap.Float4Arr xyzPosFloatArr;
67 protected final Wrap.Float4Arr xyzVelFloatArr;
68
69 protected int bodyCount;
70 protected int frameCount = 0;
71 protected final long startTime = System.currentTimeMillis();
72
73 protected final Mode mode;
74
75 public NBodyGLWindow(Arena arena, int width, int height, GLTexture particle, int bodyCount, Mode mode) {
76 super(arena, width, height, "nbody", GLUT_DOUBLE() | GLUT_RGB() | GLUT_DEPTH(), particle);
77 this.particle = particle;
78 this.bodyCount = bodyCount;
79 this.xyzPosFloatArr = Wrap.Float4Arr.of(arena, bodyCount);
80 this.xyzVelFloatArr = Wrap.Float4Arr.of(arena, bodyCount);
81
82 this.mode = mode;
83 final float maxDist = 80f;
84
85 System.out.println(bodyCount + " particles");
86
87 for (int body = 0; body < bodyCount; body++) {
88 final float theta = (float) (Math.random() * Math.PI * 2);
89 final float phi = (float) (Math.random() * Math.PI * 2);
90 final float radius = (float) (Math.random() * maxDist);
91
92 var radial = Wrap.Float4Arr.float4.of(
93 (float) (radius * Math.cos(theta) * Math.sin(phi)),
94 (float) (radius * Math.sin(theta) * Math.sin(phi)),
95 (float) (radius * Math.cos(phi)),
96 0f);
97
98 xyzPosFloatArr.set(body, radial);
99 }
100 }
101
102
103 float rot = 0f;
104
105 public static void run(int body, int size, Wrap.Float4Arr xyzPos, Wrap.Float4Arr xyzVel, float mass, float delT, float espSqr) {
106 float accx = 0.f;
107 float accy = 0.f;
108 float accz = 0.f;
109
110 final float myPosx = xyzPos.getx(body);
111 final float myPosy = xyzPos.gety(body);
112 final float myPosz = xyzPos.getz(body);
113 final float myVelx = xyzVel.getx(body);
114 final float myVely = xyzVel.gety(body);
115 final float myVelz = xyzVel.getz(body);
116
117 for (int i = 0; i < size; i++) {
118 final float dx = xyzPos.get(i).x() - myPosx;
119 final float dy = xyzPos.get(i).y() - myPosy;
120 final float dz = xyzPos.get(i).z() - myPosz;
121 final float invDist = 1 / (float) Math.sqrt((dx * dx) + (dy * dy) + (dz * dz) + espSqr);
122 final float s = mass * invDist * invDist * invDist;
123 accx = accx + (s * dx);
124 accy = accy + (s * dy);
125 accz = accz + (s * dz);
126 }
127 accx = accx * delT;
128 accy = accy * delT;
129 accz = accz * delT;
130
131 xyzPos.setx(body, myPosx + (myVelx + accx * .5f) * delT);
132 xyzPos.sety(body, myPosy + (myVely + accy * .5f) * delT);
133 xyzPos.setz(body, myPosz + (myVelz + accz * .5f) * delT);
134
135 xyzVel.setx(body, myVelx + accx);
136 xyzVel.sety(body, myVely + accy);
137 xyzVel.setz(body, myVelz + accz);
138 }
139
140 public static void runf4(int body, int size, Wrap.Float4Arr xyzPos, Wrap.Float4Arr xyzVel, float mass, float delT, float espSqr) {
141 var accf4 = Wrap.Float4Arr.float4.zero;
142 var myPosf4 = xyzPos.get(body);
143 var myVelf4 = xyzVel.get(body);
144 for (int i = 0; i < size; i++) {
145 var delta = xyzPos.get(i).sub(myPosf4); // xyz[i]-myPos
146 var dSqrd = delta.mul(delta); // delta^2
147 var invDist = 1f / (float) Math.sqrt(dSqrd.x() + dSqrd.y() + dSqrd.z() + espSqr);
148 accf4 = accf4.add(delta.mul(mass * invDist * invDist * invDist)); // accf4 += delta*(invDist^3*mass)
149 }
150 accf4 = accf4.mul(delT);
151 xyzPos.set(body, myPosf4.add(myVelf4.mul(delT)).add(accf4.mul(.5f * delT)));
152 xyzVel.set(body, myVelf4.add(accf4));
153 }
154
155 protected void moveBodies() {
156 switch (mode) {
157 case JavaMT4 -> IntStream.range(0, bodyCount).parallel().forEach(
158 i -> runf4(i, bodyCount, xyzPosFloatArr, xyzVelFloatArr, mass, delT, espSqr)
159 );
160 case JavaMT -> IntStream.range(0, bodyCount).parallel().forEach(
161 i -> run(i, bodyCount, xyzPosFloatArr, xyzVelFloatArr, mass, delT, espSqr)
162 );
163 case JavaSeq4 -> IntStream.range(0, bodyCount).forEach(
164 i -> runf4(i, bodyCount, xyzPosFloatArr, xyzVelFloatArr, mass, delT, espSqr)
165 );
166 case JavaSeq -> IntStream.range(0, bodyCount).forEach(
167 i -> run(i, bodyCount, xyzPosFloatArr, xyzVelFloatArr, mass, delT, espSqr)
168 );
169 default -> throw new RuntimeException("Should never get here");
170 }
171 }
172
173 protected static final float WEST = 0;
174 protected static final float EAST = 1;
175 protected static final float NORTH = 0;
176 protected static final float SOUTH = 1;
177 protected static float dx = -.5f;
178 protected static float dy = -.5f;
179 protected static float dz = -.5f;
180
181
182 @Override
183 public void display() {
184 moveBodies();
185 glClearColor(0f, 0f, 0f, 0f);
186 glClear(GL_COLOR_BUFFER_BIT() | GL_DEPTH_BUFFER_BIT());
187 glEnable(GL_TEXTURE_2D()); // Annoyingly important,
188 glBindTexture(GL_TEXTURE_2D(), textureBuf.get(particle.idx));
189 glPushMatrix1(() -> {
190 glScalef(.01f, .01f, .01f);
191 glColor3f(1f, 1f, 1f);
192 glQuads(() -> {
193 for (int bodyIdx = 0; bodyIdx < bodyCount; bodyIdx++) {
194 var bodyf4 = xyzPosFloatArr.get(bodyIdx);
195
196 /*
197 * Textures are mapped to a quad by defining the vertices in
198 * the order SW,NW,NE,SE
199 &
200 * 2--->3
201 * ^ |
202 * | v
203 * 1 4
204 *
205 * Here we are describing the 'texture plane' for the body.
206 * Ideally we need to rotate this to point to the camera (see billboarding)
207 */
208
209 glTexCoord2f(WEST, SOUTH);
210 glVertex3f(bodyf4.x() + WEST + dx, bodyf4.y() + SOUTH + dy, bodyf4.z() + dz);
211 glTexCoord2f(WEST, NORTH);
212 glVertex3f(bodyf4.x() + WEST + dx, bodyf4.y() + NORTH + dy, bodyf4.z() + dz);
213 glTexCoord2f(EAST, NORTH);
214 glVertex3f(bodyf4.x() + EAST + dx, bodyf4.y() + NORTH + dy, bodyf4.z() + dz);
215 glTexCoord2f(EAST, SOUTH);
216 glVertex3f(bodyf4.x() + EAST + dx, bodyf4.y() + SOUTH + dy, bodyf4.z() + dz);
217
218 }
219 });
220 });
221 glDisable(GL_TEXTURE_2D()); // Annoyingly important .. took two days to work that out
222 glMatrixMode(GL_MODELVIEW());
223 glPushMatrix1(() -> {
224 glColor3f(0.0f, 1.0f, 0.0f);
225 var font = glutBitmapTimesRoman24$segment();
226 long elapsed = System.currentTimeMillis() - startTime;
227 float secs = elapsed / 1000f;
228 var FPS = "Mode: " + mode.toString() + " Bodies " + bodyCount + " FPS: " + ((frameCount / secs));
229 glRasterPos2f(-.8f, .7f);
230 for (int c : FPS.getBytes()) {
231 glutBitmapCharacter(font, c);
232 }
233 });
234 glutSwapBuffers();
235 frameCount++;
236 }
237
238 @Override
239 public void onIdle() {
240 // rot += 1f;
241 super.onIdle();
242 }
243 }
244