void GLFWCALL PhysicsThreadFun( void *arg )
{
while( running )
{
// Lock mutex
glfwLockMutex( thread_sync.particles_lock );
// Wait for particle drawing to be done
while( running && thread_sync.p_frame > thread_sync.d_frame )
{
glfwWaitCond( thread_sync.d_done, thread_sync.particles_lock,
0.1 );
}
// No longer running?
if( !running )
{
break;
}
// Update particles
ParticleEngine( thread_sync.t, thread_sync.dt );
// Update frame counter
thread_sync.p_frame ++;
// Unlock mutex and signal drawing thread
glfwUnlockMutex( thread_sync.particles_lock );
glfwSignalCond( thread_sync.p_done );
}
}
ParticleEngine ParticleEngineBuilder::Build(){ return ParticleEngine(gBuilder,rMinBuilder,blackHoleMassBuilder,blackHoleRadiusBuilder,disappearingRadiusBuilder,minSpawnRadiusBuilder,maxSpawnRadiusBuilder,spawnVelocityBuilder,maxZSpawnDistanceBuilder,numberOfThreadsBuilder,numberOfParticlesBuilder,collisionsBuilder,integratorBuilder, gravityCutOffBuilder);}
void DrawParticles( double t, float dt )
{
int i, particle_count;
VERTEX vertex_array[ BATCH_PARTICLES * PARTICLE_VERTS ], *vptr;
float alpha;
GLuint rgba;
VEC 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 );
// Enable blending
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 );
// Is particle physics carried out in a separate thread?
if( multithreading )
{
// Wait for particle physics thread to be done
glfwLockMutex( thread_sync.particles_lock );
while( running && thread_sync.p_frame <= thread_sync.d_frame )
{
glfwWaitCond( thread_sync.p_done, thread_sync.particles_lock,
0.1 );
}
// 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 ++;
}
else
{
// Perform particle physics in this thread
ParticleEngine( t, dt );
}
// 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 = 4.0f * pptr->life;
if( alpha > 1.0f )
{
alpha = 1.0f;
}
// 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 * 255.0f);
((GLubyte *)&rgba)[1] = (GLubyte)(pptr->g * 255.0f);
((GLubyte *)&rgba)[2] = (GLubyte)(pptr->b * 255.0f);
((GLubyte *)&rgba)[3] = (GLubyte)(alpha * 255.0f);
// 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 = 0.0f;
vptr->t = 0.0f;
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 = 1.0f;
vptr->t = 0.0f;
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 = 1.0f;
vptr->t = 1.0f;
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 = 0.0f;
vptr->t = 1.0f;
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: Unlock mutex and signal physics
// thread
if( multithreading )
{
glfwUnlockMutex( thread_sync.particles_lock );
glfwSignalCond( 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 );
// Disable texturing and blending
glDisable( GL_TEXTURE_2D );
glDisable( GL_BLEND );
// Allow Z-buffer updates again
glDepthMask( GL_TRUE );
}
