First copy of es2gears.c
Source downloaded from:
https://cgit.freedesktop.org/mesa/demos/tree/src/egl/opengles2/es2gears.c
Change-Id: I12d20e45a5da1a5701d32f2c356b50fb96e5fa27
diff --git a/opengl/es2gears.c b/opengl/es2gears.c
new file mode 100644
index 0000000..37fb6a4
--- /dev/null
+++ b/opengl/es2gears.c
@@ -0,0 +1,723 @@
+/*
+ * 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
+ *
+ * Improve GLES2 port:
+ * * Refactor gear drawing.
+ * * Use correct normals for surfaces.
+ * * Improve shader.
+ * * Use perspective projection transformation.
+ * * Add FPS count.
+ * * Add comments.
+ * Alexandros Frantzis <alexandros.frantzis@linaro.org>
+ * Jul 13, 2010
+ */
+
+#define GL_GLEXT_PROTOTYPES
+#define EGL_EGLEXT_PROTOTYPES
+
+#define _GNU_SOURCE
+
+#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"
+
+#define STRIPS_PER_TOOTH 7
+#define VERTICES_PER_TOOTH 34
+#define GEAR_VERTEX_STRIDE 6
+
+/**
+ * Struct describing the vertices in triangle strip
+ */
+struct vertex_strip {
+ /** The first vertex in the strip */
+ GLint first;
+ /** The number of consecutive vertices in the strip after the first */
+ GLint count;
+};
+
+/* Each vertex consist of GEAR_VERTEX_STRIDE GLfloat attributes */
+typedef GLfloat GearVertex[GEAR_VERTEX_STRIDE];
+
+/**
+ * Struct representing a gear.
+ */
+struct gear {
+ /** The array of vertices comprising the gear */
+ GearVertex *vertices;
+ /** The number of vertices comprising the gear */
+ int nvertices;
+ /** The array of triangle strips comprising the gear */
+ struct vertex_strip *strips;
+ /** The number of triangle strips comprising the gear */
+ int nstrips;
+ /** The Vertex Buffer Object holding the vertices in the graphics card */
+ GLuint vbo;
+};
+
+/** The view rotation [x, y, z] */
+static GLfloat view_rot[3] = { 20.0, 30.0, 0.0 };
+/** The gears */
+static struct gear *gear1, *gear2, *gear3;
+/** The current gear rotation angle */
+static GLfloat angle = 0.0;
+/** The location of the shader uniforms */
+static GLuint ModelViewProjectionMatrix_location,
+ NormalMatrix_location,
+ LightSourcePosition_location,
+ MaterialColor_location;
+/** The projection matrix */
+static GLfloat ProjectionMatrix[16];
+/** The direction of the directional light for the scene */
+static const GLfloat LightSourcePosition[4] = { 5.0, 5.0, 10.0, 1.0};
+
+/**
+ * Fills a gear vertex.
+ *
+ * @param v the vertex to fill
+ * @param x the x coordinate
+ * @param y the y coordinate
+ * @param z the z coortinate
+ * @param n pointer to the normal table
+ *
+ * @return the operation error code
+ */
+static GearVertex *
+vert(GearVertex *v, GLfloat x, GLfloat y, GLfloat z, GLfloat n[3])
+{
+ v[0][0] = x;
+ v[0][1] = y;
+ v[0][2] = z;
+ v[0][3] = n[0];
+ v[0][4] = n[1];
+ v[0][5] = n[2];
+
+ return v + 1;
+}
+
+/**
+ * Create a gear wheel.
+ *
+ * @param inner_radius radius of hole at center
+ * @param outer_radius radius at center of teeth
+ * @param width width of gear
+ * @param teeth number of teeth
+ * @param tooth_depth depth of tooth
+ *
+ * @return pointer to the constructed struct gear
+ */
+static struct gear *
+create_gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
+ GLint teeth, GLfloat tooth_depth)
+{
+ GLfloat r0, r1, r2;
+ GLfloat da;
+ GearVertex *v;
+ struct gear *gear;
+ double s[5], c[5];
+ GLfloat normal[3];
+ int cur_strip = 0;
+ int i;
+
+ /* Allocate memory for the gear */
+ gear = malloc(sizeof *gear);
+ if (gear == NULL)
+ return NULL;
+
+ /* Calculate the radii used in the gear */
+ 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;
+
+ /* Allocate memory for the triangle strip information */
+ gear->nstrips = STRIPS_PER_TOOTH * teeth;
+ gear->strips = calloc(gear->nstrips, sizeof (*gear->strips));
+
+ /* Allocate memory for the vertices */
+ gear->vertices = calloc(VERTICES_PER_TOOTH * teeth, sizeof(*gear->vertices));
+ v = gear->vertices;
+
+ for (i = 0; i < teeth; i++) {
+ /* Calculate needed sin/cos for varius angles */
+ sincos(i * 2.0 * M_PI / teeth, &s[0], &c[0]);
+ 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]);
+
+ /* A set of macros for making the creation of the gears easier */
+#define GEAR_POINT(r, da) { (r) * c[(da)], (r) * s[(da)] }
+#define SET_NORMAL(x, y, z) do { \
+ normal[0] = (x); normal[1] = (y); normal[2] = (z); \
+} while(0)
+
+#define GEAR_VERT(v, point, sign) vert((v), p[(point)].x, p[(point)].y, (sign) * width * 0.5, normal)
+
+#define START_STRIP do { \
+ gear->strips[cur_strip].first = v - gear->vertices; \
+} while(0);
+
+#define END_STRIP do { \
+ int _tmp = (v - gear->vertices); \
+ gear->strips[cur_strip].count = _tmp - gear->strips[cur_strip].first; \
+ cur_strip++; \
+} while (0)
+
+#define QUAD_WITH_NORMAL(p1, p2) do { \
+ SET_NORMAL((p[(p1)].y - p[(p2)].y), -(p[(p1)].x - p[(p2)].x), 0); \
+ v = GEAR_VERT(v, (p1), -1); \
+ v = GEAR_VERT(v, (p1), 1); \
+ v = GEAR_VERT(v, (p2), -1); \
+ v = GEAR_VERT(v, (p2), 1); \
+} while(0)
+
+ struct point {
+ GLfloat x;
+ GLfloat y;
+ };
+
+ /* Create the 7 points (only x,y coords) used to draw a tooth */
+ struct point p[7] = {
+ GEAR_POINT(r2, 1), // 0
+ GEAR_POINT(r2, 2), // 1
+ GEAR_POINT(r1, 0), // 2
+ GEAR_POINT(r1, 3), // 3
+ GEAR_POINT(r0, 0), // 4
+ GEAR_POINT(r1, 4), // 5
+ GEAR_POINT(r0, 4), // 6
+ };
+
+ /* Front face */
+ START_STRIP;
+ SET_NORMAL(0, 0, 1.0);
+ v = GEAR_VERT(v, 0, +1);
+ v = GEAR_VERT(v, 1, +1);
+ v = GEAR_VERT(v, 2, +1);
+ v = GEAR_VERT(v, 3, +1);
+ v = GEAR_VERT(v, 4, +1);
+ v = GEAR_VERT(v, 5, +1);
+ v = GEAR_VERT(v, 6, +1);
+ END_STRIP;
+
+ /* Inner face */
+ START_STRIP;
+ QUAD_WITH_NORMAL(4, 6);
+ END_STRIP;
+
+ /* Back face */
+ START_STRIP;
+ SET_NORMAL(0, 0, -1.0);
+ v = GEAR_VERT(v, 6, -1);
+ v = GEAR_VERT(v, 5, -1);
+ v = GEAR_VERT(v, 4, -1);
+ v = GEAR_VERT(v, 3, -1);
+ v = GEAR_VERT(v, 2, -1);
+ v = GEAR_VERT(v, 1, -1);
+ v = GEAR_VERT(v, 0, -1);
+ END_STRIP;
+
+ /* Outer face */
+ START_STRIP;
+ QUAD_WITH_NORMAL(0, 2);
+ END_STRIP;
+
+ START_STRIP;
+ QUAD_WITH_NORMAL(1, 0);
+ END_STRIP;
+
+ START_STRIP;
+ QUAD_WITH_NORMAL(3, 1);
+ END_STRIP;
+
+ START_STRIP;
+ QUAD_WITH_NORMAL(5, 3);
+ END_STRIP;
+ }
+
+ gear->nvertices = (v - gear->vertices);
+
+ /* Store the vertices in a vertex buffer object (VBO) */
+ glGenBuffers(1, &gear->vbo);
+ glBindBuffer(GL_ARRAY_BUFFER, gear->vbo);
+ glBufferData(GL_ARRAY_BUFFER, gear->nvertices * sizeof(GearVertex),
+ gear->vertices, GL_STATIC_DRAW);
+
+ return gear;
+}
+
+/**
+ * Multiplies two 4x4 matrices.
+ *
+ * The result is stored in matrix m.
+ *
+ * @param m the first matrix to multiply
+ * @param n the second matrix to multiply
+ */
+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);
+}
+
+/**
+ * Rotates a 4x4 matrix.
+ *
+ * @param[in,out] m the matrix to rotate
+ * @param angle the angle to rotate
+ * @param x the x component of the direction to rotate to
+ * @param y the y component of the direction to rotate to
+ * @param z the z component of the direction to rotate to
+ */
+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);
+}
+
+
+/**
+ * Translates a 4x4 matrix.
+ *
+ * @param[in,out] m the matrix to translate
+ * @param x the x component of the direction to translate to
+ * @param y the y component of the direction to translate to
+ * @param z the z component of the direction to translate to
+ */
+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);
+}
+
+/**
+ * Creates an identity 4x4 matrix.
+ *
+ * @param m the matrix make an identity matrix
+ */
+static void
+identity(GLfloat *m)
+{
+ GLfloat t[16] = {
+ 1.0, 0.0, 0.0, 0.0,
+ 0.0, 1.0, 0.0, 0.0,
+ 0.0, 0.0, 1.0, 0.0,
+ 0.0, 0.0, 0.0, 1.0,
+ };
+
+ memcpy(m, t, sizeof(t));
+}
+
+/**
+ * Transposes a 4x4 matrix.
+ *
+ * @param m the matrix to transpose
+ */
+static void
+transpose(GLfloat *m)
+{
+ GLfloat t[16] = {
+ m[0], m[4], m[8], m[12],
+ m[1], m[5], m[9], m[13],
+ m[2], m[6], m[10], m[14],
+ m[3], m[7], m[11], m[15]};
+
+ memcpy(m, t, sizeof(t));
+}
+
+/**
+ * Inverts a 4x4 matrix.
+ *
+ * This function can currently handle only pure translation-rotation matrices.
+ * Read http://www.gamedev.net/community/forums/topic.asp?topic_id=425118
+ * for an explanation.
+ */
+static void
+invert(GLfloat *m)
+{
+ GLfloat t[16];
+ identity(t);
+
+ // Extract and invert the translation part 't'. The inverse of a
+ // translation matrix can be calculated by negating the translation
+ // coordinates.
+ t[12] = -m[12]; t[13] = -m[13]; t[14] = -m[14];
+
+ // Invert the rotation part 'r'. The inverse of a rotation matrix is
+ // equal to its transpose.
+ m[12] = m[13] = m[14] = 0;
+ transpose(m);
+
+ // inv(m) = inv(r) * inv(t)
+ multiply(m, t);
+}
+
+/**
+ * Calculate a perspective projection transformation.
+ *
+ * @param m the matrix to save the transformation in
+ * @param fovy the field of view in the y direction
+ * @param aspect the view aspect ratio
+ * @param zNear the near clipping plane
+ * @param zFar the far clipping plane
+ */
+void perspective(GLfloat *m, GLfloat fovy, GLfloat aspect, GLfloat zNear, GLfloat zFar)
+{
+ GLfloat tmp[16];
+ identity(tmp);
+
+ double sine, cosine, cotangent, deltaZ;
+ GLfloat radians = fovy / 2 * M_PI / 180;
+
+ deltaZ = zFar - zNear;
+ sincos(radians, &sine, &cosine);
+
+ if ((deltaZ == 0) || (sine == 0) || (aspect == 0))
+ return;
+
+ cotangent = cosine / sine;
+
+ tmp[0] = cotangent / aspect;
+ tmp[5] = cotangent;
+ tmp[10] = -(zFar + zNear) / deltaZ;
+ tmp[11] = -1;
+ tmp[14] = -2 * zNear * zFar / deltaZ;
+ tmp[15] = 0;
+
+ memcpy(m, tmp, sizeof(tmp));
+}
+
+/**
+ * Draws a gear.
+ *
+ * @param gear the gear to draw
+ * @param transform the current transformation matrix
+ * @param x the x position to draw the gear at
+ * @param y the y position to draw the gear at
+ * @param angle the rotation angle of the gear
+ * @param color the color of the gear
+ */
+static void
+draw_gear(struct gear *gear, GLfloat *transform,
+ GLfloat x, GLfloat y, GLfloat angle, const GLfloat color[4])
+{
+ GLfloat model_view[16];
+ GLfloat normal_matrix[16];
+ GLfloat model_view_projection[16];
+
+ /* Translate and rotate the gear */
+ memcpy(model_view, transform, sizeof (model_view));
+ translate(model_view, x, y, 0);
+ rotate(model_view, 2 * M_PI * angle / 360.0, 0, 0, 1);
+
+ /* Create and set the ModelViewProjectionMatrix */
+ memcpy(model_view_projection, ProjectionMatrix, sizeof(model_view_projection));
+ multiply(model_view_projection, model_view);
+
+ glUniformMatrix4fv(ModelViewProjectionMatrix_location, 1, GL_FALSE,
+ model_view_projection);
+
+ /*
+ * Create and set the NormalMatrix. It's the inverse transpose of the
+ * ModelView matrix.
+ */
+ memcpy(normal_matrix, model_view, sizeof (normal_matrix));
+ invert(normal_matrix);
+ transpose(normal_matrix);
+ glUniformMatrix4fv(NormalMatrix_location, 1, GL_FALSE, normal_matrix);
+
+ /* Set the gear color */
+ glUniform4fv(MaterialColor_location, 1, color);
+
+ /* Set the vertex buffer object to use */
+ glBindBuffer(GL_ARRAY_BUFFER, gear->vbo);
+
+ /* Set up the position of the attributes in the vertex buffer object */
+ glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE,
+ 6 * sizeof(GLfloat), NULL);
+ glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE,
+ 6 * sizeof(GLfloat), (GLfloat *) 0 + 3);
+
+ /* Enable the attributes */
+ glEnableVertexAttribArray(0);
+ glEnableVertexAttribArray(1);
+
+ /* Draw the triangle strips that comprise the gear */
+ int n;
+ for (n = 0; n < gear->nstrips; n++)
+ glDrawArrays(GL_TRIANGLE_STRIP, gear->strips[n].first, gear->strips[n].count);
+
+ /* Disable the attributes */
+ glDisableVertexAttribArray(1);
+ glDisableVertexAttribArray(0);
+}
+
+/**
+ * Draws the gears.
+ */
+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 transform[16];
+ identity(transform);
+
+ glClearColor(0.0, 0.0, 0.0, 0.0);
+ glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+ /* Translate and rotate the view */
+ translate(transform, 0, 0, -20);
+ rotate(transform, 2 * M_PI * view_rot[0] / 360.0, 1, 0, 0);
+ rotate(transform, 2 * M_PI * view_rot[1] / 360.0, 0, 1, 0);
+ rotate(transform, 2 * M_PI * view_rot[2] / 360.0, 0, 0, 1);
+
+ /* Draw the gears */
+ draw_gear(gear1, transform, -3.0, -2.0, angle, red);
+ draw_gear(gear2, transform, 3.1, -2.0, -2 * angle - 9.0, green);
+ draw_gear(gear3, transform, -3.1, 4.2, -2 * angle - 25.0, blue);
+}
+
+/**
+ * Handles a new window size or exposure.
+ *
+ * @param width the window width
+ * @param height the window height
+ */
+static void
+gears_reshape(int width, int height)
+{
+ /* Update the projection matrix */
+ perspective(ProjectionMatrix, 60.0, width / (float)height, 1.0, 1024.0);
+
+ /* Set the viewport */
+ glViewport(0, 0, (GLint) width, (GLint) height);
+}
+
+/**
+ * Handles special eglut events.
+ *
+ * @param special the event to handle.
+ */
+static void
+gears_special(int special)
+{
+ switch (special) {
+ case EGLUT_KEY_LEFT:
+ view_rot[1] += 5.0;
+ break;
+ case EGLUT_KEY_RIGHT:
+ view_rot[1] -= 5.0;
+ break;
+ case EGLUT_KEY_UP:
+ view_rot[0] += 5.0;
+ break;
+ case EGLUT_KEY_DOWN:
+ view_rot[0] -= 5.0;
+ break;
+ }
+}
+
+static void
+gears_idle(void)
+{
+ static int frames = 0;
+ static double tRot0 = -1.0, tRate0 = -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();
+ frames++;
+
+ if (tRate0 < 0.0)
+ tRate0 = t;
+ if (t - tRate0 >= 5.0) {
+ GLfloat seconds = t - tRate0;
+ GLfloat fps = frames / seconds;
+ printf("%d frames in %3.1f seconds = %6.3f FPS\n", frames, seconds,
+ fps);
+ tRate0 = t;
+ frames = 0;
+ }
+}
+
+static const char vertex_shader[] =
+"attribute vec3 position;\n"
+"attribute vec3 normal;\n"
+"\n"
+"uniform mat4 ModelViewProjectionMatrix;\n"
+"uniform mat4 NormalMatrix;\n"
+"uniform vec4 LightSourcePosition;\n"
+"uniform vec4 MaterialColor;\n"
+"\n"
+"varying vec4 Color;\n"
+"\n"
+"void main(void)\n"
+"{\n"
+" // Transform the normal to eye coordinates\n"
+" vec3 N = normalize(vec3(NormalMatrix * vec4(normal, 1.0)));\n"
+"\n"
+" // The LightSourcePosition is actually its direction for directional light\n"
+" vec3 L = normalize(LightSourcePosition.xyz);\n"
+"\n"
+" // Multiply the diffuse value by the vertex color (which is fixed in this case)\n"
+" // to get the actual color that we will use to draw this vertex with\n"
+" float diffuse = max(dot(N, L), 0.0);\n"
+" Color = diffuse * MaterialColor;\n"
+"\n"
+" // Transform the position to clip coordinates\n"
+" gl_Position = ModelViewProjectionMatrix * vec4(position, 1.0);\n"
+"}";
+
+static const char fragment_shader[] =
+"precision mediump float;\n"
+"varying vec4 Color;\n"
+"\n"
+"void main(void)\n"
+"{\n"
+" gl_FragColor = Color;\n"
+"}";
+
+static void
+gears_init(void)
+{
+ GLuint v, f, program;
+ const char *p;
+ char msg[512];
+
+ glEnable(GL_CULL_FACE);
+ glEnable(GL_DEPTH_TEST);
+
+ /* Compile the vertex shader */
+ 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);
+
+ /* Compile the fragment shader */
+ 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);
+
+ /* Create and link the shader program */
+ 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);
+
+ /* Enable the shaders */
+ glUseProgram(program);
+
+ /* Get the locations of the uniforms so we can access them */
+ ModelViewProjectionMatrix_location = glGetUniformLocation(program, "ModelViewProjectionMatrix");
+ NormalMatrix_location = glGetUniformLocation(program, "NormalMatrix");
+ LightSourcePosition_location = glGetUniformLocation(program, "LightSourcePosition");
+ MaterialColor_location = glGetUniformLocation(program, "MaterialColor");
+
+ /* Set the LightSourcePosition uniform which is constant throught the program */
+ glUniform4fv(LightSourcePosition_location, 1, LightSourcePosition);
+
+ /* make the gears */
+ gear1 = create_gear(1.0, 4.0, 1.0, 20, 0.7);
+ gear2 = create_gear(0.5, 2.0, 2.0, 10, 0.7);
+ gear3 = create_gear(1.3, 2.0, 0.5, 10, 0.7);
+}
+
+int
+main(int argc, char *argv[])
+{
+ /* Initialize the window */
+ eglutInitWindowSize(300, 300);
+ eglutInitAPIMask(EGLUT_OPENGL_ES2_BIT);
+ eglutInit(argc, argv);
+
+ eglutCreateWindow("es2gears");
+
+ /* Set up eglut callback functions */
+ eglutIdleFunc(gears_idle);
+ eglutReshapeFunc(gears_reshape);
+ eglutDisplayFunc(gears_draw);
+ eglutSpecialFunc(gears_special);
+
+ /* Initialize the gears */
+ gears_init();
+
+ eglutMainLoop();
+
+ return 0;
+}
