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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>
+#define GLFW_INCLUDE_NONE
+#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 memory 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 tessellated 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 tessellation
+ // 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);
+}
+
generated by cgit v1.2.1 (git 2.18.0) at 2024-11-01 13:41:12 +0000