346 lines
7.1 KiB
C
346 lines
7.1 KiB
C
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/*
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* Copyright (c) 1991, 1992, 1993 Silicon Graphics, Inc.
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*
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* Permission to use, copy, modify, distribute, and sell this software and
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* its documentation for any purpose is hereby granted without fee, provided
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* that (i) the above copyright notices and this permission notice appear in
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* all copies of the software and related documentation, and (ii) the name of
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* Silicon Graphics may not be used in any advertising or
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* publicity relating to the software without the specific, prior written
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* permission of Silicon Graphics.
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*
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* THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF
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* ANY KIND,
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* EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
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* WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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*
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* IN NO EVENT SHALL SILICON GRAPHICS BE LIABLE FOR
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* ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
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* OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
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* WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
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* LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
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* OF THIS SOFTWARE.
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*/
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include <math.h>
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#include <GL/glut.h>
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#ifndef PI
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#define PI 3.141592657
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#endif
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enum {
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NORMAL = 0,
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WEIRD = 1
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};
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enum {
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STREAK = 0,
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CIRCLE = 1
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};
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#define MAXSTARS 400
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#define MAXPOS 10000
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#define MAXWARP 500
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#define MAXANGLES 6000
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typedef struct _starRec {
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GLint type;
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float x[2], y[2], z[2];
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float offsetX, offsetY, offsetR, rotation;
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} starRec;
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GLenum doubleBuffer;
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GLint windW, windH;
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GLenum flag = NORMAL;
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GLint starCount = MAXSTARS / 2;
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float speed = 1.0;
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GLint nitro = 0;
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starRec stars[MAXSTARS];
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float sinTable[MAXANGLES];
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float Sin(float angle)
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{
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return (sinTable[(GLint)angle]);
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}
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float Cos(float angle)
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{
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return (sinTable[((GLint)angle+(MAXANGLES/4))%MAXANGLES]);
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}
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void NewStar(GLint n, GLint d)
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{
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if (rand()%4 == 0) {
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stars[n].type = CIRCLE;
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} else {
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stars[n].type = STREAK;
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}
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stars[n].x[0] = (float)(rand() % MAXPOS - MAXPOS / 2);
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stars[n].y[0] = (float)(rand() % MAXPOS - MAXPOS / 2);
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stars[n].z[0] = (float)(rand() % MAXPOS + d);
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if (rand()%4 == 0 && flag == WEIRD) {
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stars[n].offsetX = (float)(rand() % 100 - 100 / 2);
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stars[n].offsetY = (float)(rand() % 100 - 100 / 2);
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stars[n].offsetR = (float)(rand() % 25 - 25 / 2);
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} else {
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stars[n].offsetX = 0.0;
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stars[n].offsetY = 0.0;
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stars[n].offsetR = 0.0;
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}
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}
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void RotatePoint(float *x, float *y, float rotation)
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{
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float tmpX, tmpY;
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tmpX = *x * Cos(rotation) - *y * Sin(rotation);
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tmpY = *y * Cos(rotation) + *x * Sin(rotation);
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*x = tmpX;
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*y = tmpY;
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}
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void MoveStars(void)
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{
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float offset;
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GLint n;
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static double t0 = -1.;
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double t, dt;
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t = glutGet(GLUT_ELAPSED_TIME) / 1000.;
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if (t0 < 0.)
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t0 = t;
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dt = 85.*(t - t0);
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t0 = t;
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offset = speed * 60.0;
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for (n = 0; n < starCount; n++) {
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stars[n].x[1] = stars[n].x[0];
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stars[n].y[1] = stars[n].y[0];
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stars[n].z[1] = stars[n].z[0];
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stars[n].x[0] += stars[n].offsetX*dt;
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stars[n].y[0] += stars[n].offsetY*dt;
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stars[n].z[0] -= offset*dt;
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stars[n].rotation += stars[n].offsetR*dt;
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if (stars[n].rotation > MAXANGLES) {
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stars[n].rotation = 0.0;
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}
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else if (stars[n].rotation < 0.0) {
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stars[n].rotation += 360.0;
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}
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}
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}
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GLenum StarPoint(GLint n)
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{
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float x0, y0, x1, y1, width;
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GLint i;
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x0 = stars[n].x[0] * windW / stars[n].z[0];
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y0 = stars[n].y[0] * windH / stars[n].z[0];
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RotatePoint(&x0, &y0, stars[n].rotation);
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x0 += windW / 2.0;
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y0 += windH / 2.0;
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if (x0 >= 0.0 && x0 < windW && y0 >= 0.0 && y0 < windH) {
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if (stars[n].type == STREAK) {
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x1 = stars[n].x[1] * windW / stars[n].z[1];
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y1 = stars[n].y[1] * windH / stars[n].z[1];
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RotatePoint(&x1, &y1, stars[n].rotation);
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x1 += windW / 2.0;
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y1 += windH / 2.0;
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glLineWidth(MAXPOS/100.0/stars[n].z[0]+1.0);
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glColor3f(1.0, (MAXWARP-speed)/MAXWARP, (MAXWARP-speed)/MAXWARP);
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if (fabs(x0-x1) < 1.0 && fabs(y0-y1) < 1.0) {
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glBegin(GL_POINTS);
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glVertex2f(x0, y0);
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glEnd();
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} else {
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glBegin(GL_LINES);
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glVertex2f(x0, y0);
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glVertex2f(x1, y1);
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glEnd();
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}
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} else {
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width = MAXPOS / 10.0 / stars[n].z[0] + 1.0;
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glColor3f(1.0, 0.0, 0.0);
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glBegin(GL_POLYGON);
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for (i = 0; i < 8; i++) {
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float x = x0 + width * Cos((float)i*MAXANGLES/8.0);
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float y = y0 + width * Sin((float)i*MAXANGLES/8.0);
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glVertex2f(x, y);
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};
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glEnd();
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}
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return GL_TRUE;
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} else {
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return GL_FALSE;
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}
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}
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void ShowStars(void)
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{
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GLint n;
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glClear(GL_COLOR_BUFFER_BIT);
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for (n = 0; n < starCount; n++) {
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if (stars[n].z[0] > speed || (stars[n].z[0] > 0.0 && speed < MAXWARP)) {
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if (StarPoint(n) == GL_FALSE) {
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NewStar(n, MAXPOS);
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}
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} else {
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NewStar(n, MAXPOS);
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}
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}
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}
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static void Init(void)
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{
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float angle;
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GLint n;
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srand((unsigned int) glutGet(GLUT_ELAPSED_TIME) );
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for (n = 0; n < MAXSTARS; n++) {
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NewStar(n, 100);
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}
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angle = 0.0;
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for (n = 0; n < MAXANGLES ; n++) {
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sinTable[n] = sin(angle);
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angle += PI / (MAXANGLES / 2.0);
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}
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glClearColor(0.0, 0.0, 0.0, 0.0);
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glDisable(GL_DITHER);
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}
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void Reshape(int width, int height)
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{
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windW = (GLint)width;
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windH = (GLint)height;
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glViewport(0, 0, windW, windH);
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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gluOrtho2D(-0.5, windW+0.5, -0.5, windH+0.5);
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glMatrixMode(GL_MODELVIEW);
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}
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static void Key(unsigned char key, int x, int y)
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{
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switch (key) {
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case 27:
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exit(1);
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case 32:
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flag = (flag == NORMAL) ? WEIRD : NORMAL;
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break;
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case 't':
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nitro = 1;
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break;
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default:
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return;
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}
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}
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void Draw(void)
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{
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MoveStars();
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ShowStars();
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if (nitro > 0) {
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speed = (float)(nitro / 10) + 1.0;
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if (speed > MAXWARP) {
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speed = MAXWARP;
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}
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if (++nitro > MAXWARP*10) {
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nitro = -nitro;
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}
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} else if (nitro < 0) {
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nitro++;
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speed = (float)(-nitro / 10) + 1.0;
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if (speed > MAXWARP) {
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speed = MAXWARP;
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}
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}
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glFlush();
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if (doubleBuffer) {
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glutSwapBuffers();
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}
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}
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static GLenum Args(int argc, char **argv)
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{
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GLint i;
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doubleBuffer = GL_TRUE;
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for (i = 1; i < argc; i++) {
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if (strcmp(argv[i], "-sb") == 0) {
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doubleBuffer = GL_FALSE;
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} else if (strcmp(argv[i], "-db") == 0) {
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doubleBuffer = GL_TRUE;
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}
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}
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return GL_TRUE;
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}
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#if !defined(GLUTCALLBACK)
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#define GLUTCALLBACK
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#endif
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void GLUTCALLBACK glut_post_redisplay_p(void)
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{
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glutPostRedisplay();
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}
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int main(int argc, char **argv)
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{
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GLenum type;
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glutInit(&argc, argv);
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if (Args(argc, argv) == GL_FALSE) {
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exit(1);
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}
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windW = 300;
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windH = 300;
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glutInitWindowPosition(0, 0); glutInitWindowSize( 300, 300);
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type = GLUT_RGB;
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type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
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glutInitDisplayMode(type);
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if (glutCreateWindow("Stars") == GL_FALSE) {
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exit(1);
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}
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Init();
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glutReshapeFunc(Reshape);
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glutKeyboardFunc(Key);
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glutDisplayFunc(Draw);
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glutIdleFunc(glut_post_redisplay_p);
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glutMainLoop();
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return 0;
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}
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