492 lines
12 KiB
C
492 lines
12 KiB
C
/*
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* Use glCopyTexSubImage2D to draw animated gears on the sides of a box.
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*
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* Brian Paul
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* 27 January 2006
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*/
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#include <math.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <GL/glut.h>
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#ifndef M_PI
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#define M_PI 3.14159265
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#endif
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static GLint WinWidth = 800, WinHeight = 500;
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static GLint TexWidth, TexHeight;
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static GLuint TexObj = 1;
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static GLenum IntFormat = GL_RGB;
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static GLboolean WireFrame = GL_FALSE;
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static GLint T0 = 0;
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static GLint Frames = 0;
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static GLint Win = 0;
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static GLfloat ViewRotX = 20.0, ViewRotY = 30.0, ViewRotZ = 0.0;
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static GLint Gear1, Gear2, Gear3;
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static GLfloat GearRot = 0.0;
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static GLfloat CubeRot = 0.0;
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/**
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Draw a gear wheel. You'll probably want to call this function when
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building a display list since we do a lot of trig here.
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Input: inner_radius - radius of hole at center
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outer_radius - radius at center of teeth
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width - width of gear
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teeth - number of teeth
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tooth_depth - depth of tooth
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**/
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static void
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gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
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GLint teeth, GLfloat tooth_depth)
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{
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GLint i;
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GLfloat r0, r1, r2;
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GLfloat angle, da;
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GLfloat u, v, len;
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r0 = inner_radius;
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r1 = outer_radius - tooth_depth / 2.0;
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r2 = outer_radius + tooth_depth / 2.0;
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da = 2.0 * M_PI / teeth / 4.0;
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glShadeModel(GL_FLAT);
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glNormal3f(0.0, 0.0, 1.0);
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/* draw front face */
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glBegin(GL_QUAD_STRIP);
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for (i = 0; i <= teeth; i++) {
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angle = i * 2.0 * M_PI / teeth;
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glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
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glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
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if (i < teeth) {
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glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
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glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
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}
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}
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glEnd();
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/* draw front sides of teeth */
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glBegin(GL_QUADS);
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da = 2.0 * M_PI / teeth / 4.0;
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for (i = 0; i < teeth; i++) {
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angle = i * 2.0 * M_PI / teeth;
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glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
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glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
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glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), width * 0.5);
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glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
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}
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glEnd();
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glNormal3f(0.0, 0.0, -1.0);
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/* draw back face */
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glBegin(GL_QUAD_STRIP);
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for (i = 0; i <= teeth; i++) {
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angle = i * 2.0 * M_PI / teeth;
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glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
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glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
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if (i < teeth) {
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glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
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glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
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}
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}
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glEnd();
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/* draw back sides of teeth */
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glBegin(GL_QUADS);
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da = 2.0 * M_PI / teeth / 4.0;
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for (i = 0; i < teeth; i++) {
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angle = i * 2.0 * M_PI / teeth;
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glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
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glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), -width * 0.5);
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glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
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glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
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}
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glEnd();
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/* draw outward faces of teeth */
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glBegin(GL_QUAD_STRIP);
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for (i = 0; i < teeth; i++) {
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angle = i * 2.0 * M_PI / teeth;
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glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
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glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
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u = r2 * cos(angle + da) - r1 * cos(angle);
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v = r2 * sin(angle + da) - r1 * sin(angle);
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len = sqrt(u * u + v * v);
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u /= len;
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v /= len;
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glNormal3f(v, -u, 0.0);
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glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
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glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
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glNormal3f(cos(angle), sin(angle), 0.0);
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glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), width * 0.5);
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glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), -width * 0.5);
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u = r1 * cos(angle + 3 * da) - r2 * cos(angle + 2 * da);
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v = r1 * sin(angle + 3 * da) - r2 * sin(angle + 2 * da);
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glNormal3f(v, -u, 0.0);
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glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
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glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
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glNormal3f(cos(angle), sin(angle), 0.0);
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}
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glVertex3f(r1 * cos(0), r1 * sin(0), width * 0.5);
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glVertex3f(r1 * cos(0), r1 * sin(0), -width * 0.5);
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glEnd();
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glShadeModel(GL_SMOOTH);
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/* draw inside radius cylinder */
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glBegin(GL_QUAD_STRIP);
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for (i = 0; i <= teeth; i++) {
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angle = i * 2.0 * M_PI / teeth;
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glNormal3f(-cos(angle), -sin(angle), 0.0);
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glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
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glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
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}
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glEnd();
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}
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static void
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cleanup(void)
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{
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glDeleteTextures(1, &TexObj);
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glDeleteLists(Gear1, 1);
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glDeleteLists(Gear2, 1);
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glDeleteLists(Gear3, 1);
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glutDestroyWindow(Win);
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}
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static void
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DrawGears(void)
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{
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if (WireFrame) {
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glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
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}
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glPushMatrix();
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glRotatef(20/*ViewRotX*/, 1.0, 0.0, 0.0);
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glRotatef(ViewRotY, 0.0, 1.0, 0.0);
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glRotatef(ViewRotZ, 0.0, 0.0, 1.0);
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glPushMatrix();
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glTranslatef(-3.0, -2.0, 0.0);
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glRotatef(GearRot, 0.0, 0.0, 1.0);
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glCallList(Gear1);
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glPopMatrix();
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glPushMatrix();
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glTranslatef(3.1, -2.0, 0.0);
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glRotatef(-2.0 * GearRot - 9.0, 0.0, 0.0, 1.0);
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glCallList(Gear2);
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glPopMatrix();
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glPushMatrix();
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glTranslatef(-3.1, 4.2, 0.0);
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glRotatef(-2.0 * GearRot - 25.0, 0.0, 0.0, 1.0);
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glCallList(Gear3);
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glPopMatrix();
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glPopMatrix();
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glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
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}
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static void
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DrawCube(void)
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{
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static const GLfloat texcoords[4][2] = {
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{ 0, 0 }, { 1, 0 }, { 1, 1 }, { 0, 1 }
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};
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static const GLfloat vertices[4][2] = {
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{ -1, -1 }, { 1, -1 }, { 1, 1 }, { -1, 1 }
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};
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static const GLfloat xforms[6][4] = {
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{ 0, 0, 1, 0 },
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{ 90, 0, 1, 0 },
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{ 180, 0, 1, 0 },
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{ 270, 0, 1, 0 },
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{ 90, 1, 0, 0 },
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{ -90, 1, 0, 0 }
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};
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static const GLfloat mat[4] = { 1.0, 1.0, 0.5, 1.0 };
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GLint i, j;
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glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, mat);
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glEnable(GL_TEXTURE_2D);
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glPushMatrix();
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glRotatef(ViewRotX, 1.0, 0.0, 0.0);
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glRotatef(15, 1, 0, 0);
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glRotatef(CubeRot, 0, 1, 0);
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glScalef(4, 4, 4);
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for (i = 0; i < 6; i++) {
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glPushMatrix();
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glRotatef(xforms[i][0], xforms[i][1], xforms[i][2], xforms[i][3]);
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glTranslatef(0, 0, 1.1);
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glBegin(GL_POLYGON);
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glNormal3f(0, 0, 1);
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for (j = 0; j < 4; j++) {
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glTexCoord2fv(texcoords[j]);
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glVertex2fv(vertices[j]);
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}
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glEnd();
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glPopMatrix();
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}
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glPopMatrix();
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glDisable(GL_TEXTURE_2D);
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}
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static void
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draw(void)
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{
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float ar;
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glMatrixMode(GL_MODELVIEW);
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glLoadIdentity();
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glTranslatef(0.0, 0.0, -40.0);
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/* clear whole depth buffer */
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glDisable(GL_SCISSOR_TEST);
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glClear(GL_DEPTH_BUFFER_BIT);
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glEnable(GL_SCISSOR_TEST);
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/* clear upper-left corner of color buffer (unused space) */
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glScissor(0, TexHeight, TexWidth, WinHeight - TexHeight);
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glClearColor(0.0, 0.0, 0.0, 0.0);
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glClear(GL_COLOR_BUFFER_BIT);
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/* clear lower-left corner of color buffer */
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glViewport(0, 0, TexWidth, TexHeight);
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glScissor(0, 0, TexWidth, TexHeight);
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glClearColor(1, 1, 1, 0);
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glClear(GL_COLOR_BUFFER_BIT);
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/* draw gears in lower-left corner */
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 60.0);
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glMatrixMode(GL_MODELVIEW);
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DrawGears();
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/* copy color buffer to texture */
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glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, TexWidth, TexHeight);
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/* clear right half of color buffer */
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glViewport(TexWidth, 0, WinWidth - TexWidth, WinHeight);
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glScissor(TexWidth, 0, WinWidth - TexWidth, WinHeight);
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glClearColor(0.5, 0.5, 0.8, 0.0);
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glClear(GL_COLOR_BUFFER_BIT);
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/* draw textured cube in right half of window */
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ar = (float) (WinWidth - TexWidth) / WinHeight;
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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glFrustum(-ar, ar, -1.0, 1.0, 5.0, 60.0);
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glMatrixMode(GL_MODELVIEW);
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DrawCube();
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/* finish up */
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glutSwapBuffers();
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Frames++;
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{
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GLint t = glutGet(GLUT_ELAPSED_TIME);
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if (t - T0 >= 5000) {
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GLfloat seconds = (t - T0) / 1000.0;
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GLfloat fps = Frames / seconds;
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printf("%d frames in %6.3f seconds = %6.3f FPS\n", Frames, seconds, fps);
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T0 = t;
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Frames = 0;
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}
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}
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}
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static void
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idle(void)
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{
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static double t0 = -1.;
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double dt, t = glutGet(GLUT_ELAPSED_TIME) / 1000.0;
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if (t0 < 0.0)
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t0 = t;
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dt = t - t0;
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t0 = t;
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/* fmod to prevent overflow */
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GearRot = fmod(GearRot + 70.0 * dt, 360.0); /* 70 deg/sec */
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CubeRot = fmod(CubeRot + 15.0 * dt, 360.0); /* 15 deg/sec */
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glutPostRedisplay();
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}
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/* change view angle, exit upon ESC */
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static void
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key(unsigned char k, int x, int y)
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{
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(void) x;
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(void) y;
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switch (k) {
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case 'w':
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WireFrame = !WireFrame;
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break;
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case 'z':
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ViewRotZ += 5.0;
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break;
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case 'Z':
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ViewRotZ -= 5.0;
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break;
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case 27: /* Escape */
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cleanup();
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exit(0);
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break;
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default:
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return;
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}
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glutPostRedisplay();
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}
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/* change view angle */
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static void
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special(int k, int x, int y)
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{
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(void) x;
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(void) y;
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switch (k) {
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case GLUT_KEY_UP:
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ViewRotX += 5.0;
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break;
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case GLUT_KEY_DOWN:
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ViewRotX -= 5.0;
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break;
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case GLUT_KEY_LEFT:
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ViewRotY += 5.0;
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break;
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case GLUT_KEY_RIGHT:
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ViewRotY -= 5.0;
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break;
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default:
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return;
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}
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glutPostRedisplay();
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}
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/* new window size or exposure */
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static void
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reshape(int width, int height)
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{
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WinWidth = width;
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WinHeight = height;
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}
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static void
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init(int argc, char *argv[])
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{
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static GLfloat pos[4] = {5.0, 5.0, 10.0, 0.0};
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static GLfloat red[4] = {0.8, 0.1, 0.0, 1.0};
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static GLfloat green[4] = {0.0, 0.8, 0.2, 1.0};
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static GLfloat blue[4] = {0.2, 0.2, 1.0, 1.0};
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GLint i;
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glLightfv(GL_LIGHT0, GL_POSITION, pos);
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#if 0
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glEnable(GL_CULL_FACE);
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#endif
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glEnable(GL_LIGHTING);
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glEnable(GL_LIGHT0);
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glEnable(GL_DEPTH_TEST);
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/* make the gears */
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Gear1 = glGenLists(1);
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glNewList(Gear1, GL_COMPILE);
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glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, red);
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gear(1.0, 4.0, 1.0, 20, 0.7);
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glEndList();
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Gear2 = glGenLists(1);
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glNewList(Gear2, GL_COMPILE);
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glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green);
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gear(0.5, 2.0, 2.0, 10, 0.7);
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glEndList();
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Gear3 = glGenLists(1);
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glNewList(Gear3, GL_COMPILE);
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glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, blue);
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gear(1.3, 2.0, 0.5, 10, 0.7);
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glEndList();
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glEnable(GL_NORMALIZE);
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/* xxx make size dynamic */
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TexWidth = 256;
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TexHeight = 256;
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glBindTexture(GL_TEXTURE_2D, TexObj);
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glTexImage2D(GL_TEXTURE_2D, 0, IntFormat, TexWidth, TexHeight, 0,
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GL_RGBA, GL_UNSIGNED_BYTE, NULL);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
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glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
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for ( i=1; i<argc; i++ ) {
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if (strcmp(argv[i], "-info")==0) {
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printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
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printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
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printf("GL_VENDOR = %s\n", (char *) glGetString(GL_VENDOR));
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printf("GL_EXTENSIONS = %s\n", (char *) glGetString(GL_EXTENSIONS));
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}
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}
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}
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static void
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visible(int vis)
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{
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if (vis == GLUT_VISIBLE)
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glutIdleFunc(idle);
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else
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glutIdleFunc(NULL);
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}
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int
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main(int argc, char *argv[])
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{
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glutInit(&argc, argv);
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glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);
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glutInitWindowSize(WinWidth, WinHeight);
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Win = glutCreateWindow("gearbox");
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init(argc, argv);
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glutDisplayFunc(draw);
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glutReshapeFunc(reshape);
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glutKeyboardFunc(key);
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glutSpecialFunc(special);
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glutVisibilityFunc(visible);
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glutMainLoop();
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return 0; /* ANSI C requires main to return int. */
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}
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