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emscripten
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emscripten/tests/hello_world_gles_full.c

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20 KiB
C
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/*
* 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>
#ifdef __APPLE__
#include <OpenGL/gl.h>
#include <Glut/glut.h>
#else
#include <GL/gl.h>
#include <GL/glut.h>
#endif
#define STRIPS_PER_TOOTH 7
#define VERTICES_PER_TOOTH 34
#define GEAR_VERTEX_STRIDE 6
#ifndef HAVE_BUILTIN_SINCOS
#define sincos _sincos
static void
sincos (double a, double *s, double *c)
{
*s = sin (a);
*c = cos (a);
}
#endif
/**
* 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, 0);
/* Set up the position of the attributes in the vertex buffer object */
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE,
6 * sizeof(GLfloat), *gear->vertices);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE,
6 * sizeof(GLfloat), ((float*)*gear->vertices) + 3*4);
/* 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);
glutSwapBuffers();
}
/**
* 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 glut events.
*
* @param special the event to handle.
*/
static void
gears_special(int special, int crap, int morecrap)
{
switch (special) {
case GLUT_KEY_LEFT:
view_rot[1] += 5.0;
break;
case GLUT_KEY_RIGHT:
view_rot[1] -= 5.0;
break;
case GLUT_KEY_UP:
view_rot[0] += 5.0;
break;
case GLUT_KEY_DOWN:
view_rot[0] -= 5.0;
break;
case GLUT_KEY_F11:
glutFullScreen();
break;
}
}
static void
gears_idle(void)
{
static int frames = 0;
static double tRot0 = -1.0, tRate0 = -1.0;
double dt, t = glutGet(GLUT_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;
glutPostRedisplay();
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[] =
"#ifdef GL_ES\n"
"precision mediump float;\n"
"#endif\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 */
glutInit(&argc, argv);
glutInitWindowSize(300, 300);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutCreateWindow("es2gears");
/* Set up glut callback functions */
glutIdleFunc (gears_idle);
glutReshapeFunc(gears_reshape);
glutDisplayFunc(gears_draw);
glutSpecialFunc(gears_special);
/* Initialize the gears */
gears_init();
glutMainLoop();
return 0;
}
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