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glfw/examples/particles.c
Camilla Löwy d7e30b1c74 Replace glad and the Vulkan SDK with glad2 
This removes all dependencies from the GLFW test programs on the Vulkan
SDK.

It also removes support for linking the GLFW shared library (dynamic
library, DLL) against the Vulkan loader static library.
2019-04-15 02:45:48 +02:00

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//========================================================================
// A simple particle engine with threaded physics
// Copyright (c) Marcus Geelnard
// Copyright (c) Camilla Löwy <elmindreda@glfw.org>
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software. If you use this software
// in a product, an acknowledgment in the product documentation would
// be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not
// be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source
// distribution.
//
//========================================================================
#if defined(_MSC_VER)
// Make MS math.h define M_PI
#define _USE_MATH_DEFINES
#endif
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <time.h>
#include <tinycthread.h>
#include <getopt.h>
#include <linmath.h>
#include <glad/gl.h>
#include <GLFW/glfw3.h>
// Define tokens for GL_EXT_separate_specular_color if not already defined
#ifndef GL_EXT_separate_specular_color
#define GL_LIGHT_MODEL_COLOR_CONTROL_EXT 0x81F8
#define GL_SINGLE_COLOR_EXT 0x81F9
#define GL_SEPARATE_SPECULAR_COLOR_EXT 0x81FA
#endif // GL_EXT_separate_specular_color
//========================================================================
// Type definitions
//========================================================================
typedef struct
{
float x, y, z;
} Vec3;
// This structure is used for interleaved vertex arrays (see the
// draw_particles function)
//
// NOTE: This structure SHOULD be packed on most systems. It uses 32-bit fields
// on 32-bit boundaries, and is a multiple of 64 bits in total (6x32=3x64). If
// it does not work, try using pragmas or whatever to force the structure to be
// packed.
typedef struct
{
GLfloat s, t; // Texture coordinates
GLuint rgba; // Color (four ubytes packed into an uint)
GLfloat x, y, z; // Vertex coordinates
} Vertex;
//========================================================================
// Program control global variables
//========================================================================
// Window dimensions
float aspect_ratio;
// "wireframe" flag (true if we use wireframe view)
int wireframe;
// Thread synchronization
struct {
double t; // Time (s)
float dt; // Time since last frame (s)
int p_frame; // Particle physics frame number
int d_frame; // Particle draw frame number
cnd_t p_done; // Condition: particle physics done
cnd_t d_done; // Condition: particle draw done
mtx_t particles_lock; // Particles data sharing mutex
} thread_sync;
//========================================================================
// Texture declarations (we hard-code them into the source code, since
// they are so simple)
//========================================================================
#define P_TEX_WIDTH 8 // Particle texture dimensions
#define P_TEX_HEIGHT 8
#define F_TEX_WIDTH 16 // Floor texture dimensions
#define F_TEX_HEIGHT 16
// Texture object IDs
GLuint particle_tex_id, floor_tex_id;
// Particle texture (a simple spot)
const unsigned char particle_texture[ P_TEX_WIDTH * P_TEX_HEIGHT ] = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x11, 0x22, 0x22, 0x11, 0x00, 0x00,
0x00, 0x11, 0x33, 0x88, 0x77, 0x33, 0x11, 0x00,
0x00, 0x22, 0x88, 0xff, 0xee, 0x77, 0x22, 0x00,
0x00, 0x22, 0x77, 0xee, 0xff, 0x88, 0x22, 0x00,
0x00, 0x11, 0x33, 0x77, 0x88, 0x33, 0x11, 0x00,
0x00, 0x00, 0x11, 0x33, 0x22, 0x11, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};
// Floor texture (your basic checkered floor)
const unsigned char floor_texture[ F_TEX_WIDTH * F_TEX_HEIGHT ] = {
0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
0xff, 0xf0, 0xcc, 0xf0, 0xf0, 0xf0, 0xff, 0xf0, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
0xf0, 0xcc, 0xee, 0xff, 0xf0, 0xf0, 0xf0, 0xf0, 0x30, 0x66, 0x30, 0x30, 0x30, 0x20, 0x30, 0x30,
0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xee, 0xf0, 0xf0, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
0xf0, 0xf0, 0xf0, 0xf0, 0xcc, 0xf0, 0xf0, 0xf0, 0x30, 0x30, 0x55, 0x30, 0x30, 0x44, 0x30, 0x30,
0xf0, 0xdd, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0x33, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xff, 0xf0, 0xf0, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x60, 0x30,
0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0x33, 0x33, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x33, 0x30, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0,
0x30, 0x30, 0x30, 0x30, 0x30, 0x20, 0x30, 0x30, 0xf0, 0xff, 0xf0, 0xf0, 0xdd, 0xf0, 0xf0, 0xff,
0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x55, 0x33, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xff, 0xf0, 0xf0,
0x30, 0x44, 0x66, 0x30, 0x30, 0x30, 0x30, 0x30, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0,
0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0xf0, 0xf0, 0xf0, 0xaa, 0xf0, 0xf0, 0xcc, 0xf0,
0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0xff, 0xf0, 0xf0, 0xf0, 0xff, 0xf0, 0xdd, 0xf0,
0x30, 0x30, 0x30, 0x77, 0x30, 0x30, 0x30, 0x30, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0,
0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0,
};
//========================================================================
// These are fixed constants that control the particle engine. In a
// modular world, these values should be variables...
//========================================================================
// Maximum number of particles
#define MAX_PARTICLES 3000
// Life span of a particle (in seconds)
#define LIFE_SPAN 8.f
// A new particle is born every [BIRTH_INTERVAL] second
#define BIRTH_INTERVAL (LIFE_SPAN/(float)MAX_PARTICLES)
// Particle size (meters)
#define PARTICLE_SIZE 0.7f
// Gravitational constant (m/s^2)
#define GRAVITY 9.8f
// Base initial velocity (m/s)
#define VELOCITY 8.f
// Bounce friction (1.0 = no friction, 0.0 = maximum friction)
#define FRICTION 0.75f
// "Fountain" height (m)
#define FOUNTAIN_HEIGHT 3.f
// Fountain radius (m)
#define FOUNTAIN_RADIUS 1.6f
// Minimum delta-time for particle phisics (s)
#define MIN_DELTA_T (BIRTH_INTERVAL * 0.5f)
//========================================================================
// Particle system global variables
//========================================================================
// This structure holds all state for a single particle
typedef struct {
float x,y,z; // Position in space
float vx,vy,vz; // Velocity vector
float r,g,b; // Color of particle
float life; // Life of particle (1.0 = newborn, < 0.0 = dead)
int active; // Tells if this particle is active
} PARTICLE;
// Global vectors holding all particles. We use two vectors for double
// buffering.
static PARTICLE particles[MAX_PARTICLES];
// Global variable holding the age of the youngest particle
static float min_age;
// Color of latest born particle (used for fountain lighting)
static float glow_color[4];
// Position of latest born particle (used for fountain lighting)
static float glow_pos[4];
//========================================================================
// Object material and fog configuration constants
//========================================================================
const GLfloat fountain_diffuse[4] = { 0.7f, 1.f, 1.f, 1.f };
const GLfloat fountain_specular[4] = { 1.f, 1.f, 1.f, 1.f };
const GLfloat fountain_shininess = 12.f;
const GLfloat floor_diffuse[4] = { 1.f, 0.6f, 0.6f, 1.f };
const GLfloat floor_specular[4] = { 0.6f, 0.6f, 0.6f, 1.f };
const GLfloat floor_shininess = 18.f;
const GLfloat fog_color[4] = { 0.1f, 0.1f, 0.1f, 1.f };
//========================================================================
// Print usage information
//========================================================================
static void usage(void)
{
printf("Usage: particles [-bfhs]\n");
printf("Options:\n");
printf(" -f Run in full screen\n");
printf(" -h Display this help\n");
printf(" -s Run program as single thread (default is to use two threads)\n");
printf("\n");
printf("Program runtime controls:\n");
printf(" W Toggle wireframe mode\n");
printf(" Esc Exit program\n");
}
//========================================================================
// Initialize a new particle
//========================================================================
static void init_particle(PARTICLE *p, double t)
{
float xy_angle, velocity;
// Start position of particle is at the fountain blow-out
p->x = 0.f;
p->y = 0.f;
p->z = FOUNTAIN_HEIGHT;
// Start velocity is up (Z)...
p->vz = 0.7f + (0.3f / 4096.f) * (float) (rand() & 4095);
// ...and a randomly chosen X/Y direction
xy_angle = (2.f * (float) M_PI / 4096.f) * (float) (rand() & 4095);
p->vx = 0.4f * (float) cos(xy_angle);
p->vy = 0.4f * (float) sin(xy_angle);
// Scale velocity vector according to a time-varying velocity
velocity = VELOCITY * (0.8f + 0.1f * (float) (sin(0.5 * t) + sin(1.31 * t)));
p->vx *= velocity;
p->vy *= velocity;
p->vz *= velocity;
// Color is time-varying
p->r = 0.7f + 0.3f * (float) sin(0.34 * t + 0.1);
p->g = 0.6f + 0.4f * (float) sin(0.63 * t + 1.1);
p->b = 0.6f + 0.4f * (float) sin(0.91 * t + 2.1);
// Store settings for fountain glow lighting
glow_pos[0] = 0.4f * (float) sin(1.34 * t);
glow_pos[1] = 0.4f * (float) sin(3.11 * t);
glow_pos[2] = FOUNTAIN_HEIGHT + 1.f;
glow_pos[3] = 1.f;
glow_color[0] = p->r;
glow_color[1] = p->g;
glow_color[2] = p->b;
glow_color[3] = 1.f;
// The particle is new-born and active
p->life = 1.f;
p->active = 1;
}
//========================================================================
// Update a particle
//========================================================================
#define FOUNTAIN_R2 (FOUNTAIN_RADIUS+PARTICLE_SIZE/2)*(FOUNTAIN_RADIUS+PARTICLE_SIZE/2)
static void update_particle(PARTICLE *p, float dt)
{
// If the particle is not active, we need not do anything
if (!p->active)
return;
// The particle is getting older...
p->life -= dt * (1.f / LIFE_SPAN);
// Did the particle die?
if (p->life <= 0.f)
{
p->active = 0;
return;
}
// Apply gravity
p->vz = p->vz - GRAVITY * dt;
// Update particle position
p->x = p->x + p->vx * dt;
p->y = p->y + p->vy * dt;
p->z = p->z + p->vz * dt;
// Simple collision detection + response
if (p->vz < 0.f)
{
// Particles should bounce on the fountain (with friction)
if ((p->x * p->x + p->y * p->y) < FOUNTAIN_R2 &&
p->z < (FOUNTAIN_HEIGHT + PARTICLE_SIZE / 2))
{
p->vz = -FRICTION * p->vz;
p->z = FOUNTAIN_HEIGHT + PARTICLE_SIZE / 2 +
FRICTION * (FOUNTAIN_HEIGHT +
PARTICLE_SIZE / 2 - p->z);
}
// Particles should bounce on the floor (with friction)
else if (p->z < PARTICLE_SIZE / 2)
{
p->vz = -FRICTION * p->vz;
p->z = PARTICLE_SIZE / 2 +
FRICTION * (PARTICLE_SIZE / 2 - p->z);
}
}
}
//========================================================================
// The main frame for the particle engine. Called once per frame.
//========================================================================
static void particle_engine(double t, float dt)
{
int i;
float dt2;
// Update particles (iterated several times per frame if dt is too large)
while (dt > 0.f)
{
// Calculate delta time for this iteration
dt2 = dt < MIN_DELTA_T ? dt : MIN_DELTA_T;
for (i = 0; i < MAX_PARTICLES; i++)
update_particle(&particles[i], dt2);
min_age += dt2;
// Should we create any new particle(s)?
while (min_age >= BIRTH_INTERVAL)
{
min_age -= BIRTH_INTERVAL;
// Find a dead particle to replace with a new one
for (i = 0; i < MAX_PARTICLES; i++)
{
if (!particles[i].active)
{
init_particle(&particles[i], t + min_age);
update_particle(&particles[i], min_age);
break;
}
}
}
dt -= dt2;
}
}
//========================================================================
// Draw all active particles. We use OpenGL 1.1 vertex
// arrays for this in order to accelerate the drawing.
//========================================================================
#define BATCH_PARTICLES 70 // Number of particles to draw in each batch
// (70 corresponds to 7.5 KB = will not blow
// the L1 data cache on most CPUs)
#define PARTICLE_VERTS 4 // Number of vertices per particle
static void draw_particles(GLFWwindow* window, double t, float dt)
{
int i, particle_count;
Vertex vertex_array[BATCH_PARTICLES * PARTICLE_VERTS];
Vertex* vptr;
float alpha;
GLuint rgba;
Vec3 quad_lower_left, quad_lower_right;
GLfloat mat[16];
PARTICLE* pptr;
// Here comes the real trick with flat single primitive objects (s.c.
// "billboards"): We must rotate the textured primitive so that it
// always faces the viewer (is coplanar with the view-plane).
// We:
// 1) Create the primitive around origo (0,0,0)
// 2) Rotate it so that it is coplanar with the view plane
// 3) Translate it according to the particle position
// Note that 1) and 2) is the same for all particles (done only once).
// Get modelview matrix. We will only use the upper left 3x3 part of
// the matrix, which represents the rotation.
glGetFloatv(GL_MODELVIEW_MATRIX, mat);
// 1) & 2) We do it in one swift step:
// Although not obvious, the following six lines represent two matrix/
// vector multiplications. The matrix is the inverse 3x3 rotation
// matrix (i.e. the transpose of the same matrix), and the two vectors
// represent the lower left corner of the quad, PARTICLE_SIZE/2 *
// (-1,-1,0), and the lower right corner, PARTICLE_SIZE/2 * (1,-1,0).
// The upper left/right corners of the quad is always the negative of
// the opposite corners (regardless of rotation).
quad_lower_left.x = (-PARTICLE_SIZE / 2) * (mat[0] + mat[1]);
quad_lower_left.y = (-PARTICLE_SIZE / 2) * (mat[4] + mat[5]);
quad_lower_left.z = (-PARTICLE_SIZE / 2) * (mat[8] + mat[9]);
quad_lower_right.x = (PARTICLE_SIZE / 2) * (mat[0] - mat[1]);
quad_lower_right.y = (PARTICLE_SIZE / 2) * (mat[4] - mat[5]);
quad_lower_right.z = (PARTICLE_SIZE / 2) * (mat[8] - mat[9]);
// Don't update z-buffer, since all particles are transparent!
glDepthMask(GL_FALSE);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE);
// Select particle texture
if (!wireframe)
{
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, particle_tex_id);
}
// Set up vertex arrays. We use interleaved arrays, which is easier to
// handle (in most situations) and it gives a linear memeory access
// access pattern (which may give better performance in some
// situations). GL_T2F_C4UB_V3F means: 2 floats for texture coords,
// 4 ubytes for color and 3 floats for vertex coord (in that order).
// Most OpenGL cards / drivers are optimized for this format.
glInterleavedArrays(GL_T2F_C4UB_V3F, 0, vertex_array);
// Wait for particle physics thread to be done
mtx_lock(&thread_sync.particles_lock);
while (!glfwWindowShouldClose(window) &&
thread_sync.p_frame <= thread_sync.d_frame)
{
struct timespec ts;
clock_gettime(CLOCK_REALTIME, &ts);
ts.tv_nsec += 100 * 1000 * 1000;
ts.tv_sec += ts.tv_nsec / (1000 * 1000 * 1000);
ts.tv_nsec %= 1000 * 1000 * 1000;
cnd_timedwait(&thread_sync.p_done, &thread_sync.particles_lock, &ts);
}
// Store the frame time and delta time for the physics thread
thread_sync.t = t;
thread_sync.dt = dt;
// Update frame counter
thread_sync.d_frame++;
// Loop through all particles and build vertex arrays.
particle_count = 0;
vptr = vertex_array;
pptr = particles;
for (i = 0; i < MAX_PARTICLES; i++)
{
if (pptr->active)
{
// Calculate particle intensity (we set it to max during 75%
// of its life, then it fades out)
alpha = 4.f * pptr->life;
if (alpha > 1.f)
alpha = 1.f;
// Convert color from float to 8-bit (store it in a 32-bit
// integer using endian independent type casting)
((GLubyte*) &rgba)[0] = (GLubyte)(pptr->r * 255.f);
((GLubyte*) &rgba)[1] = (GLubyte)(pptr->g * 255.f);
((GLubyte*) &rgba)[2] = (GLubyte)(pptr->b * 255.f);
((GLubyte*) &rgba)[3] = (GLubyte)(alpha * 255.f);
// 3) Translate the quad to the correct position in modelview
// space and store its parameters in vertex arrays (we also
// store texture coord and color information for each vertex).
// Lower left corner
vptr->s = 0.f;
vptr->t = 0.f;
vptr->rgba = rgba;
vptr->x = pptr->x + quad_lower_left.x;
vptr->y = pptr->y + quad_lower_left.y;
vptr->z = pptr->z + quad_lower_left.z;
vptr ++;
// Lower right corner
vptr->s = 1.f;
vptr->t = 0.f;
vptr->rgba = rgba;
vptr->x = pptr->x + quad_lower_right.x;
vptr->y = pptr->y + quad_lower_right.y;
vptr->z = pptr->z + quad_lower_right.z;
vptr ++;
// Upper right corner
vptr->s = 1.f;
vptr->t = 1.f;
vptr->rgba = rgba;
vptr->x = pptr->x - quad_lower_left.x;
vptr->y = pptr->y - quad_lower_left.y;
vptr->z = pptr->z - quad_lower_left.z;
vptr ++;
// Upper left corner
vptr->s = 0.f;
vptr->t = 1.f;
vptr->rgba = rgba;
vptr->x = pptr->x - quad_lower_right.x;
vptr->y = pptr->y - quad_lower_right.y;
vptr->z = pptr->z - quad_lower_right.z;
vptr ++;
// Increase count of drawable particles
particle_count ++;
}
// If we have filled up one batch of particles, draw it as a set
// of quads using glDrawArrays.
if (particle_count >= BATCH_PARTICLES)
{
// The first argument tells which primitive type we use (QUAD)
// The second argument tells the index of the first vertex (0)
// The last argument is the vertex count
glDrawArrays(GL_QUADS, 0, PARTICLE_VERTS * particle_count);
particle_count = 0;
vptr = vertex_array;
}
// Next particle
pptr++;
}
// We are done with the particle data
mtx_unlock(&thread_sync.particles_lock);
cnd_signal(&thread_sync.d_done);
// Draw final batch of particles (if any)
glDrawArrays(GL_QUADS, 0, PARTICLE_VERTS * particle_count);
// Disable vertex arrays (Note: glInterleavedArrays implicitly called
// glEnableClientState for vertex, texture coord and color arrays)
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glDisableClientState(GL_COLOR_ARRAY);
glDisable(GL_TEXTURE_2D);
glDisable(GL_BLEND);
glDepthMask(GL_TRUE);
}
//========================================================================
// Fountain geometry specification
//========================================================================
#define FOUNTAIN_SIDE_POINTS 14
#define FOUNTAIN_SWEEP_STEPS 32
static const float fountain_side[FOUNTAIN_SIDE_POINTS * 2] =
{
1.2f, 0.f, 1.f, 0.2f, 0.41f, 0.3f, 0.4f, 0.35f,
0.4f, 1.95f, 0.41f, 2.f, 0.8f, 2.2f, 1.2f, 2.4f,
1.5f, 2.7f, 1.55f,2.95f, 1.6f, 3.f, 1.f, 3.f,
0.5f, 3.f, 0.f, 3.f
};
static const float fountain_normal[FOUNTAIN_SIDE_POINTS * 2] =
{
1.0000f, 0.0000f, 0.6428f, 0.7660f, 0.3420f, 0.9397f, 1.0000f, 0.0000f,
1.0000f, 0.0000f, 0.3420f,-0.9397f, 0.4226f,-0.9063f, 0.5000f,-0.8660f,
0.7660f,-0.6428f, 0.9063f,-0.4226f, 0.0000f,1.00000f, 0.0000f,1.00000f,
0.0000f,1.00000f, 0.0000f,1.00000f
};
//========================================================================
// Draw a fountain
//========================================================================
static void draw_fountain(void)
{
static GLuint fountain_list = 0;
double angle;
float x, y;
int m, n;
// The first time, we build the fountain display list
if (!fountain_list)
{
fountain_list = glGenLists(1);
glNewList(fountain_list, GL_COMPILE_AND_EXECUTE);
glMaterialfv(GL_FRONT, GL_DIFFUSE, fountain_diffuse);
glMaterialfv(GL_FRONT, GL_SPECULAR, fountain_specular);
glMaterialf(GL_FRONT, GL_SHININESS, fountain_shininess);
// Build fountain using triangle strips
for (n = 0; n < FOUNTAIN_SIDE_POINTS - 1; n++)
{
glBegin(GL_TRIANGLE_STRIP);
for (m = 0; m <= FOUNTAIN_SWEEP_STEPS; m++)
{
angle = (double) m * (2.0 * M_PI / (double) FOUNTAIN_SWEEP_STEPS);
x = (float) cos(angle);
y = (float) sin(angle);
// Draw triangle strip
glNormal3f(x * fountain_normal[n * 2 + 2],
y * fountain_normal[n * 2 + 2],
fountain_normal[n * 2 + 3]);
glVertex3f(x * fountain_side[n * 2 + 2],
y * fountain_side[n * 2 + 2],
fountain_side[n * 2 +3 ]);
glNormal3f(x * fountain_normal[n * 2],
y * fountain_normal[n * 2],
fountain_normal[n * 2 + 1]);
glVertex3f(x * fountain_side[n * 2],
y * fountain_side[n * 2],
fountain_side[n * 2 + 1]);
}
glEnd();
}
glEndList();
}
else
glCallList(fountain_list);
}
//========================================================================
// Recursive function for building variable tesselated floor
//========================================================================
static void tessellate_floor(float x1, float y1, float x2, float y2, int depth)
{
float delta, x, y;
// Last recursion?
if (depth >= 5)
delta = 999999.f;
else
{
x = (float) (fabs(x1) < fabs(x2) ? fabs(x1) : fabs(x2));
y = (float) (fabs(y1) < fabs(y2) ? fabs(y1) : fabs(y2));
delta = x*x + y*y;
}
// Recurse further?
if (delta < 0.1f)
{
x = (x1 + x2) * 0.5f;
y = (y1 + y2) * 0.5f;
tessellate_floor(x1, y1, x, y, depth + 1);
tessellate_floor(x, y1, x2, y, depth + 1);
tessellate_floor(x1, y, x, y2, depth + 1);
tessellate_floor(x, y, x2, y2, depth + 1);
}
else
{
glTexCoord2f(x1 * 30.f, y1 * 30.f);
glVertex3f( x1 * 80.f, y1 * 80.f, 0.f);
glTexCoord2f(x2 * 30.f, y1 * 30.f);
glVertex3f( x2 * 80.f, y1 * 80.f, 0.f);
glTexCoord2f(x2 * 30.f, y2 * 30.f);
glVertex3f( x2 * 80.f, y2 * 80.f, 0.f);
glTexCoord2f(x1 * 30.f, y2 * 30.f);
glVertex3f( x1 * 80.f, y2 * 80.f, 0.f);
}
}
//========================================================================
// Draw floor. We build the floor recursively and let the tessellation in the
// center (near x,y=0,0) be high, while the tessellation around the edges be
// low.
//========================================================================
static void draw_floor(void)
{
static GLuint floor_list = 0;
if (!wireframe)
{
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, floor_tex_id);
}
// The first time, we build the floor display list
if (!floor_list)
{
floor_list = glGenLists(1);
glNewList(floor_list, GL_COMPILE_AND_EXECUTE);
glMaterialfv(GL_FRONT, GL_DIFFUSE, floor_diffuse);
glMaterialfv(GL_FRONT, GL_SPECULAR, floor_specular);
glMaterialf(GL_FRONT, GL_SHININESS, floor_shininess);
// Draw floor as a bunch of triangle strips (high tesselation
// improves lighting)
glNormal3f(0.f, 0.f, 1.f);
glBegin(GL_QUADS);
tessellate_floor(-1.f, -1.f, 0.f, 0.f, 0);
tessellate_floor( 0.f, -1.f, 1.f, 0.f, 0);
tessellate_floor( 0.f, 0.f, 1.f, 1.f, 0);
tessellate_floor(-1.f, 0.f, 0.f, 1.f, 0);
glEnd();
glEndList();
}
else
glCallList(floor_list);
glDisable(GL_TEXTURE_2D);
}
//========================================================================
// Position and configure light sources
//========================================================================
static void setup_lights(void)
{
float l1pos[4], l1amb[4], l1dif[4], l1spec[4];
float l2pos[4], l2amb[4], l2dif[4], l2spec[4];
// Set light source 1 parameters
l1pos[0] = 0.f; l1pos[1] = -9.f; l1pos[2] = 8.f; l1pos[3] = 1.f;
l1amb[0] = 0.2f; l1amb[1] = 0.2f; l1amb[2] = 0.2f; l1amb[3] = 1.f;
l1dif[0] = 0.8f; l1dif[1] = 0.4f; l1dif[2] = 0.2f; l1dif[3] = 1.f;
l1spec[0] = 1.f; l1spec[1] = 0.6f; l1spec[2] = 0.2f; l1spec[3] = 0.f;
// Set light source 2 parameters
l2pos[0] = -15.f; l2pos[1] = 12.f; l2pos[2] = 1.5f; l2pos[3] = 1.f;
l2amb[0] = 0.f; l2amb[1] = 0.f; l2amb[2] = 0.f; l2amb[3] = 1.f;
l2dif[0] = 0.2f; l2dif[1] = 0.4f; l2dif[2] = 0.8f; l2dif[3] = 1.f;
l2spec[0] = 0.2f; l2spec[1] = 0.6f; l2spec[2] = 1.f; l2spec[3] = 0.f;
glLightfv(GL_LIGHT1, GL_POSITION, l1pos);
glLightfv(GL_LIGHT1, GL_AMBIENT, l1amb);
glLightfv(GL_LIGHT1, GL_DIFFUSE, l1dif);
glLightfv(GL_LIGHT1, GL_SPECULAR, l1spec);
glLightfv(GL_LIGHT2, GL_POSITION, l2pos);
glLightfv(GL_LIGHT2, GL_AMBIENT, l2amb);
glLightfv(GL_LIGHT2, GL_DIFFUSE, l2dif);
glLightfv(GL_LIGHT2, GL_SPECULAR, l2spec);
glLightfv(GL_LIGHT3, GL_POSITION, glow_pos);
glLightfv(GL_LIGHT3, GL_DIFFUSE, glow_color);
glLightfv(GL_LIGHT3, GL_SPECULAR, glow_color);
glEnable(GL_LIGHT1);
glEnable(GL_LIGHT2);
glEnable(GL_LIGHT3);
}
//========================================================================
// Main rendering function
//========================================================================
static void draw_scene(GLFWwindow* window, double t)
{
double xpos, ypos, zpos, angle_x, angle_y, angle_z;
static double t_old = 0.0;
float dt;
mat4x4 projection;
// Calculate frame-to-frame delta time
dt = (float) (t - t_old);
t_old = t;
mat4x4_perspective(projection,
65.f * (float) M_PI / 180.f,
aspect_ratio,
1.0, 60.0);
glClearColor(0.1f, 0.1f, 0.1f, 1.f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
glLoadMatrixf((const GLfloat*) projection);
// Setup camera
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
// Rotate camera
angle_x = 90.0 - 10.0;
angle_y = 10.0 * sin(0.3 * t);
angle_z = 10.0 * t;
glRotated(-angle_x, 1.0, 0.0, 0.0);
glRotated(-angle_y, 0.0, 1.0, 0.0);
glRotated(-angle_z, 0.0, 0.0, 1.0);
// Translate camera
xpos = 15.0 * sin((M_PI / 180.0) * angle_z) +
2.0 * sin((M_PI / 180.0) * 3.1 * t);
ypos = -15.0 * cos((M_PI / 180.0) * angle_z) +
2.0 * cos((M_PI / 180.0) * 2.9 * t);
zpos = 4.0 + 2.0 * cos((M_PI / 180.0) * 4.9 * t);
glTranslated(-xpos, -ypos, -zpos);
glFrontFace(GL_CCW);
glCullFace(GL_BACK);
glEnable(GL_CULL_FACE);
setup_lights();
glEnable(GL_LIGHTING);
glEnable(GL_FOG);
glFogi(GL_FOG_MODE, GL_EXP);
glFogf(GL_FOG_DENSITY, 0.05f);
glFogfv(GL_FOG_COLOR, fog_color);
draw_floor();
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glDepthMask(GL_TRUE);
draw_fountain();
glDisable(GL_LIGHTING);
glDisable(GL_FOG);
// Particles must be drawn after all solid objects have been drawn
draw_particles(window, t, dt);
// Z-buffer not needed anymore
glDisable(GL_DEPTH_TEST);
}
//========================================================================
// Window resize callback function
//========================================================================
static void resize_callback(GLFWwindow* window, int width, int height)
{
glViewport(0, 0, width, height);
aspect_ratio = height ? width / (float) height : 1.f;
}
//========================================================================
// Key callback functions
//========================================================================
static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
if (action == GLFW_PRESS)
{
switch (key)
{
case GLFW_KEY_ESCAPE:
glfwSetWindowShouldClose(window, GLFW_TRUE);
break;
case GLFW_KEY_W:
wireframe = !wireframe;
glPolygonMode(GL_FRONT_AND_BACK,
wireframe ? GL_LINE : GL_FILL);
break;
default:
break;
}
}
}
//========================================================================
// Thread for updating particle physics
//========================================================================
static int physics_thread_main(void* arg)
{
GLFWwindow* window = arg;
for (;;)
{
mtx_lock(&thread_sync.particles_lock);
// Wait for particle drawing to be done
while (!glfwWindowShouldClose(window) &&
thread_sync.p_frame > thread_sync.d_frame)
{
struct timespec ts;
clock_gettime(CLOCK_REALTIME, &ts);
ts.tv_nsec += 100 * 1000 * 1000;
ts.tv_sec += ts.tv_nsec / (1000 * 1000 * 1000);
ts.tv_nsec %= 1000 * 1000 * 1000;
cnd_timedwait(&thread_sync.d_done, &thread_sync.particles_lock, &ts);
}
if (glfwWindowShouldClose(window))
break;
// Update particles
particle_engine(thread_sync.t, thread_sync.dt);
// Update frame counter
thread_sync.p_frame++;
// Unlock mutex and signal drawing thread
mtx_unlock(&thread_sync.particles_lock);
cnd_signal(&thread_sync.p_done);
}
return 0;
}
//========================================================================
// main
//========================================================================
int main(int argc, char** argv)
{
int ch, width, height;
thrd_t physics_thread = 0;
GLFWwindow* window;
GLFWmonitor* monitor = NULL;
if (!glfwInit())
{
fprintf(stderr, "Failed to initialize GLFW\n");
exit(EXIT_FAILURE);
}
while ((ch = getopt(argc, argv, "fh")) != -1)
{
switch (ch)
{
case 'f':
monitor = glfwGetPrimaryMonitor();
break;
case 'h':
usage();
exit(EXIT_SUCCESS);
}
}
if (monitor)
{
const GLFWvidmode* mode = glfwGetVideoMode(monitor);
glfwWindowHint(GLFW_RED_BITS, mode->redBits);
glfwWindowHint(GLFW_GREEN_BITS, mode->greenBits);
glfwWindowHint(GLFW_BLUE_BITS, mode->blueBits);
glfwWindowHint(GLFW_REFRESH_RATE, mode->refreshRate);
width = mode->width;
height = mode->height;
}
else
{
width = 640;
height = 480;
}
window = glfwCreateWindow(width, height, "Particle Engine", monitor, NULL);
if (!window)
{
fprintf(stderr, "Failed to create GLFW window\n");
glfwTerminate();
exit(EXIT_FAILURE);
}
if (monitor)
glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
glfwMakeContextCurrent(window);
gladLoadGL(glfwGetProcAddress);
glfwSwapInterval(1);
glfwSetFramebufferSizeCallback(window, resize_callback);
glfwSetKeyCallback(window, key_callback);
// Set initial aspect ratio
glfwGetFramebufferSize(window, &width, &height);
resize_callback(window, width, height);
// Upload particle texture
glGenTextures(1, &particle_tex_id);
glBindTexture(GL_TEXTURE_2D, particle_tex_id);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, P_TEX_WIDTH, P_TEX_HEIGHT,
0, GL_LUMINANCE, GL_UNSIGNED_BYTE, particle_texture);
// Upload floor texture
glGenTextures(1, &floor_tex_id);
glBindTexture(GL_TEXTURE_2D, floor_tex_id);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, F_TEX_WIDTH, F_TEX_HEIGHT,
0, GL_LUMINANCE, GL_UNSIGNED_BYTE, floor_texture);
if (glfwExtensionSupported("GL_EXT_separate_specular_color"))
{
glLightModeli(GL_LIGHT_MODEL_COLOR_CONTROL_EXT,
GL_SEPARATE_SPECULAR_COLOR_EXT);
}
// Set filled polygon mode as default (not wireframe)
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
wireframe = 0;
// Set initial times
thread_sync.t = 0.0;
thread_sync.dt = 0.001f;
thread_sync.p_frame = 0;
thread_sync.d_frame = 0;
mtx_init(&thread_sync.particles_lock, mtx_timed);
cnd_init(&thread_sync.p_done);
cnd_init(&thread_sync.d_done);
if (thrd_create(&physics_thread, physics_thread_main, window) != thrd_success)
{
glfwTerminate();
exit(EXIT_FAILURE);
}
glfwSetTime(0.0);
while (!glfwWindowShouldClose(window))
{
draw_scene(window, glfwGetTime());
glfwSwapBuffers(window);
glfwPollEvents();
}
thrd_join(physics_thread, NULL);
glfwDestroyWindow(window);
glfwTerminate();
exit(EXIT_SUCCESS);
}
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