/*
* Copyright (C) 1999-2001 Brian Paul All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/*
* Ported to GLES2.
* Kristian Høgsberg <krh@bitplanet.net>
* May 3, 2010
*/
/*
* Command line options:
* -info print GL implementation information
*
*/
#define GL_GLEXT_PROTOTYPES
#define EGL_EGLEXT_PROTOTYPES
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/time.h>
#include <unistd.h>
#include <GLES2/gl2.h>
#include <EGL/egl.h>
#include <EGL/eglext.h>
#include "eglut.h"
struct gear {
GLfloat *vertices;
GLuint vbo;
int count;
};
static GLfloat view_rotx = 20.0, view_roty = 30.0, view_rotz = 0.0;
static struct gear *gear1, *gear2, *gear3;
static GLfloat angle = 0.0;
static GLuint proj_location, light_location, color_location;
static GLfloat proj[16];
static GLfloat *
vert(GLfloat *p, GLfloat x, GLfloat y, GLfloat z, GLfloat *n)
{
p[0] = x;
p[1] = y;
p[2] = z;
p[3] = n[0];
p[4] = n[1];
p[5] = n[2];
return p + 6;
}
/* Draw a gear wheel. You'll probably want to call this function when
* building a display list since we do a lot of trig here.
*
* Input: inner_radius - radius of hole at center
* outer_radius - radius at center of teeth
* width - width of gear
* teeth - number of teeth
* tooth_depth - depth of tooth
*/
static struct gear *
gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
GLint teeth, GLfloat tooth_depth)
{
GLint i;
GLfloat r0, r1, r2;
GLfloat da;
GLfloat *p, *v;
struct gear *gear;
double s[5], c[5];
GLfloat verts[3 * 14], normal[3];
const int tris_per_tooth = 20;
gear = malloc(sizeof *gear);
if (gear == NULL)
return NULL;
r0 = inner_radius;
r1 = outer_radius - tooth_depth / 2.0;
r2 = outer_radius + tooth_depth / 2.0;
da = 2.0 * M_PI / teeth / 4.0;
gear->vertices = calloc(teeth * tris_per_tooth * 3 * 6,
sizeof *gear->vertices);
s[4] = 0;
c[4] = 1;
v = gear->vertices;
for (i = 0; i < teeth; i++) {
s[0] = s[4];
c[0] = c[4];
sincos(i * 2.0 * M_PI / teeth + da, &s[1], &c[1]);
sincos(i * 2.0 * M_PI / teeth + da * 2, &s[2], &c[2]);
sincos(i * 2.0 * M_PI / teeth + da * 3, &s[3], &c[3]);
sincos(i * 2.0 * M_PI / teeth + da * 4, &s[4], &c[4]);
normal[0] = 0.0;
normal[1] = 0.0;
normal[2] = 1.0;
v = vert(v, r2 * c[1], r2 * s[1], width * 0.5, normal);
v = vert(v, r2 * c[1], r2 * s[1], width * 0.5, normal);
v = vert(v, r2 * c[2], r2 * s[2], width * 0.5, normal);
v = vert(v, r1 * c[0], r1 * s[0], width * 0.5, normal);
v = vert(v, r1 * c[3], r1 * s[3], width * 0.5, normal);
v = vert(v, r0 * c[0], r0 * s[0], width * 0.5, normal);
v = vert(v, r1 * c[4], r1 * s[4], width * 0.5, normal);
v = vert(v, r0 * c[4], r0 * s[4], width * 0.5, normal);
v = vert(v, r0 * c[4], r0 * s[4], width * 0.5, normal);
v = vert(v, r0 * c[0], r0 * s[0], width * 0.5, normal);
v = vert(v, r0 * c[4], r0 * s[4], -width * 0.5, normal);
v = vert(v, r0 * c[0], r0 * s[0], -width * 0.5, normal);
normal[0] = 0.0;
normal[1] = 0.0;
normal[2] = -1.0;
v = vert(v, r0 * c[4], r0 * s[4], -width * 0.5, normal);
v = vert(v, r0 * c[4], r0 * s[4], -width * 0.5, normal);
v = vert(v, r1 * c[4], r1 * s[4], -width * 0.5, normal);
v = vert(v, r0 * c[0], r0 * s[0], -width * 0.5, normal);
v = vert(v, r1 * c[3], r1 * s[3], -width * 0.5, normal);
v = vert(v, r1 * c[0], r1 * s[0], -width * 0.5, normal);
v = vert(v, r2 * c[2], r2 * s[2], -width * 0.5, normal);
v = vert(v, r2 * c[1], r2 * s[1], -width * 0.5, normal);
v = vert(v, r1 * c[0], r1 * s[0], width * 0.5, normal);
v = vert(v, r1 * c[0], r1 * s[0], width * 0.5, normal);
v = vert(v, r1 * c[0], r1 * s[0], -width * 0.5, normal);
v = vert(v, r2 * c[1], r2 * s[1], width * 0.5, normal);
v = vert(v, r2 * c[1], r2 * s[1], -width * 0.5, normal);
v = vert(v, r2 * c[2], r2 * s[2], width * 0.5, normal);
v = vert(v, r2 * c[2], r2 * s[2], -width * 0.5, normal);
v = vert(v, r1 * c[3], r1 * s[3], width * 0.5, normal);
v = vert(v, r1 * c[3], r1 * s[3], -width * 0.5, normal);
v = vert(v, r1 * c[4], r1 * s[4], width * 0.5, normal);
v = vert(v, r1 * c[4], r1 * s[4], -width * 0.5, normal);
v = vert(v, r1 * c[4], r1 * s[4], -width * 0.5, normal);
}
gear->count = (v - gear->vertices) / 6;
glGenBuffers(1, &gear->vbo);
glBindBuffer(GL_ARRAY_BUFFER, gear->vbo);
glBufferData(GL_ARRAY_BUFFER, gear->count * 6 * 4,
gear->vertices, GL_STATIC_DRAW);
return gear;
}
static void
multiply(GLfloat *m, const GLfloat *n)
{
GLfloat tmp[16];
const GLfloat *row, *column;
div_t d;
int i, j;
for (i = 0; i < 16; i++) {
tmp[i] = 0;
d = div(i, 4);
row = n + d.quot * 4;
column = m + d.rem;
for (j = 0; j < 4; j++)
tmp[i] += row[j] * column[j * 4];
}
memcpy(m, &tmp, sizeof tmp);
}
static void
rotate(GLfloat *m, GLfloat angle, GLfloat x, GLfloat y, GLfloat z)
{
double s, c;
sincos(angle, &s, &c);
GLfloat r[16] = {
x * x * (1 - c) + c, y * x * (1 - c) + z * s, x * z * (1 - c) - y * s, 0,
x * y * (1 - c) - z * s, y * y * (1 - c) + c, y * z * (1 - c) + x * s, 0,
x * z * (1 - c) + y * s, y * z * (1 - c) - x * s, z * z * (1 - c) + c, 0,
0, 0, 0, 1
};
multiply(m, r);
}
static void
translate(GLfloat *m, GLfloat x, GLfloat y, GLfloat z)
{
GLfloat t[16] = { 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, x, y, z, 1 };
multiply(m, t);
}
static const GLfloat light[3] = { 1.0, 1.0, -1.0 };
static void
draw_gear(struct gear *gear, GLfloat *m,
GLfloat x, GLfloat y, GLfloat angle, const GLfloat *color)
{
GLfloat tmp[16];
memcpy(tmp, m, sizeof tmp);
translate(tmp, x, y, 0);
rotate(tmp, 2 * M_PI * angle / 360.0, 0, 0, 1);
glUniformMatrix4fv(proj_location, 1, GL_FALSE, tmp);
glUniform3fv(light_location, 1, light);
glUniform4fv(color_location, 1, color);
glBindBuffer(GL_ARRAY_BUFFER, gear->vbo);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE,
6 * sizeof(GLfloat), NULL);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE,
6 * sizeof(GLfloat), (GLfloat *) 0 + 3);
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
glDrawArrays(GL_TRIANGLE_STRIP, 0, gear->count);
}
static void
gears_draw(void)
{
const static GLfloat red[4] = { 0.8, 0.1, 0.0, 1.0 };
const static GLfloat green[4] = { 0.0, 0.8, 0.2, 1.0 };
const static GLfloat blue[4] = { 0.2, 0.2, 1.0, 1.0 };
GLfloat m[16];
glClearColor(0.0, 0.0, 0.0, 0.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
memcpy(m, proj, sizeof m);
rotate(m, 2 * M_PI * view_rotx / 360.0, 1, 0, 0);
rotate(m, 2 * M_PI * view_roty / 360.0, 0, 1, 0);
rotate(m, 2 * M_PI * view_rotz / 360.0, 0, 0, 1);
draw_gear(gear1, m, -3.0, -2.0, angle, red);
draw_gear(gear2, m, 3.1, -2.0, -2 * angle - 9.0, green);
draw_gear(gear3, m, -3.1, 4.2, -2 * angle - 25.0, blue);
}
/* new window size or exposure */
static void
gears_reshape(int width, int height)
{
GLfloat ar, m[16] = {
1.0, 0.0, 0.0, 0.0,
0.0, 1.0, 0.0, 0.0,
0.0, 0.0, 0.1, 0.0,
0.0, 0.0, 0.0, 1.0,
};
if (width < height)
ar = width;
else
ar = height;
m[0] = 0.1 * ar / width;
m[5] = 0.1 * ar / height;
memcpy(proj, m, sizeof proj);
glViewport(0, 0, (GLint) width, (GLint) height);
}
static void
gears_special(int special)
{
switch (special) {
case EGLUT_KEY_LEFT:
view_roty += 5.0;
break;
case EGLUT_KEY_RIGHT:
view_roty -= 5.0;
break;
case EGLUT_KEY_UP:
view_rotx += 5.0;
break;
case EGLUT_KEY_DOWN:
view_rotx -= 5.0;
break;
}
}
static void
gears_idle(void)
{
static double tRot0 = -1.0;
double dt, t = eglutGet(EGLUT_ELAPSED_TIME) / 1000.0;
if (tRot0 < 0.0)
tRot0 = t;
dt = t - tRot0;
tRot0 = t;
/* advance rotation for next frame */
angle += 70.0 * dt; /* 70 degrees per second */
if (angle > 3600.0)
angle -= 3600.0;
eglutPostRedisplay();
}
static const char vertex_shader[] =
"uniform mat4 proj;\n"
"attribute vec4 position;\n"
"attribute vec4 normal;\n"
"varying vec3 rotated_normal;\n"
"varying vec3 rotated_position;\n"
"vec4 tmp;\n"
"void main()\n"
"{\n"
" gl_Position = proj * position;\n"
" rotated_position = gl_Position.xyz;\n"
" tmp = proj * normal;\n"
" rotated_normal = tmp.xyz;\n"
"}\n";
static const char fragment_shader[] =
//"precision mediump float;\n"
"uniform vec4 color;\n"
"uniform vec3 light;\n"
"varying vec3 rotated_normal;\n"
"varying vec3 rotated_position;\n"
"vec3 light_direction;\n"
"vec4 white = vec4(1.0, 1.0, 1.0, 1.0);\n"
"void main()\n"
"{\n"
" light_direction = normalize(light - rotated_position);\n"
" gl_FragColor = color + white * dot(light_direction, rotated_normal);\n"
"}\n";
static void
gears_init(void)
{
GLuint v, f, program;
const char *p;
char msg[512];
glEnable(GL_CULL_FACE);
glEnable(GL_DEPTH_TEST);
p = vertex_shader;
v = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(v, 1, &p, NULL);
glCompileShader(v);
glGetShaderInfoLog(v, sizeof msg, NULL, msg);
printf("vertex shader info: %s\n", msg);
p = fragment_shader;
f = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(f, 1, &p, NULL);
glCompileShader(f);
glGetShaderInfoLog(f, sizeof msg, NULL, msg);
printf("fragment shader info: %s\n", msg);
program = glCreateProgram();
glAttachShader(program, v);
glAttachShader(program, f);
glBindAttribLocation(program, 0, "position");
glBindAttribLocation(program, 1, "normal");
glLinkProgram(program);
glGetProgramInfoLog(program, sizeof msg, NULL, msg);
printf("info: %s\n", msg);
glUseProgram(program);
proj_location = glGetUniformLocation(program, "proj");
light_location = glGetUniformLocation(program, "light");
color_location = glGetUniformLocation(program, "color");
/* make the gears */
gear1 = gear(1.0, 4.0, 1.0, 20, 0.7);
gear2 = gear(0.5, 2.0, 2.0, 10, 0.7);
gear3 = gear(1.3, 2.0, 0.5, 10, 0.7);
}
int
main(int argc, char *argv[])
{
eglutInitWindowSize(300, 300);
eglutInitAPIMask(EGLUT_OPENGL_ES2_BIT);
eglutInit(argc, argv);
eglutCreateWindow("es2gears");
eglutIdleFunc(gears_idle);
eglutReshapeFunc(gears_reshape);
eglutDisplayFunc(gears_draw);
eglutSpecialFunc(gears_special);
gears_init();
eglutMainLoop();
return 0;
}