Vec2 pos;
Vec2 vel;
+ float vis_height;
+
Particle *next, *prev;
};
static void calc_contrib_bounds(const Vec2 &pos, float mass, Rect *rect);
static void add_influence(const Vec2 &pos, float mass, float radius, const Rect &cbox);
+static Vec2 calc_field_grad(int gidx);
+
static void destroy_quadmesh(QuadMesh *m);
static void draw_quadmesh(const QuadMesh *m, unsigned int prim = GL_QUADS);
static void gen_quad_plane(QuadMesh *mesh, float width, float height, int usub, int vsub);
static void spawn_particle(const Vec2 &pos, const Vec2 &vel, float mass);
-static void add_particle(Particle *p, int grid_idx);
-static void remove_particle(Particle *p, int grid_idx);
+static void add_particle(Particle *p);
+static void remove_particle(Particle *p);
static Particle *alloc_particle();
void free_particle(Particle *p);
static Particle *grid_part[GRID_SIZE * GRID_SIZE];
static Texture *grid_tex;
-#define NUM_PARTICLE_LISTS 16
-static Particle *plist[NUM_PARTICLE_LISTS];
-#define GRID_IDX_PLIST(idx) ((idx) * NUM_PARTICLE_LISTS / (GRID_SIZE * GRID_SIZE))
+static Particle *plist;
static std::vector<Emitter*> emitters;
static Texture *gvis_tex; // texture tile for visualizing a grid
static unsigned int field_sdr;
-static int tess_level = 32;
+static int tess_level = 64;
static float field_scale = 16.0f;
static QuadMesh field_mesh;
static void simstep()
{
+ // move existing particles
+ Particle *p = plist;
+ while(p) {
+ // calculate the field gradient at the particle position
+ int gidx = pos_to_grid(p->pos.x, p->pos.y);
+ Vec2 grad = calc_field_grad(gidx);
+
+ p->vel += grad * SIM_DT;
+ p->pos += p->vel * SIM_DT;
+
+ // find the grid cell it's moving to
+ int gidx_next = pos_to_grid(p->pos.x, p->pos.y);
+ p->vis_height = 0.0f;//-grid[gidx_next] * field_scale;
+
+ if(gidx_next == gidx) {
+ p = p->next;
+ continue;
+ }
+
+ Particle *destp = grid_part[gidx_next];
+ if(destp) {
+ assert(destp != p);
+ // another particle at the destination, merge them
+ destp->vel += p->vel;
+ destp->mass += p->mass;
+ destp->radius = MASS_TO_RADIUS(destp->mass);
+
+ // ... and remove it
+ grid_part[gidx] = 0;
+ Particle *next = p->next;
+ remove_particle(p);
+ free_particle(p);
+ p = next;
+ } else {
+ // destination is empty, go there
+ if(gidx != gidx_next) {
+ grid_part[gidx] = 0;
+ grid_part[gidx_next] = p;
+ }
+
+ p = p->next;
+ }
+ }
+
+ // TODO destroy particles which left the simulation field
+
// spawn particles
int num_emitters = emitters.size();
for(int i=0; i<num_emitters; i++) {
}
// calculate gravitational field - assume field within radius constant: m / r^2
-
// first clear the field, and then add contributions
memset(grid, 0, sizeof grid);
}
// contribution of particles
- for(int i=0; i<NUM_PARTICLE_LISTS; i++) {
- Particle *p = plist[i];
- while(p) {
- Rect cbox;
- calc_contrib_bounds(p->pos, p->mass, &cbox);
- add_influence(p->pos, p->mass, p->radius, cbox);
- p = p->next;
- }
+ p = plist;
+ while(p) {
+ Rect cbox;
+ calc_contrib_bounds(p->pos, p->mass, &cbox);
+ add_influence(p->pos, p->mass, p->radius, cbox);
+ p = p->next;
}
// update texture
Emitter *em = new Emitter;
em->pos = emit_place_pos;
em->mass = 100;
- em->rate = 1;
- em->chunk = 0.05 * em->mass;
+ em->rate = 10;
+ em->chunk = 0.01 * em->mass;
em->angle = -1;
em->spread = 0;
em->spawn_pending = 0;
// draw particles
glUseProgram(particle_sdr);
- for(int i=0; i<NUM_PARTICLE_LISTS; i++) {
- Particle *p = plist[i];
- while(p) {
- int gidx = pos_to_grid(p->pos.x, p->pos.y);
+ Particle *p = plist;
+ while(p) {
+ int gidx = pos_to_grid(p->pos.x, p->pos.y);
- glPushMatrix();
- glTranslatef(p->pos.x, -grid[gidx] * field_scale, p->pos.y);
- glScalef(p->radius, p->radius, p->radius);
+ glPushMatrix();
+ glTranslatef(p->pos.x, p->vis_height, p->pos.y);
+ glScalef(p->radius, p->radius, p->radius);
- pmesh->draw();
+ pmesh->draw();
- glPopMatrix();
- p = p->next;
- }
+ glPopMatrix();
+ p = p->next;
}
glUseProgram(0);
}
}
+static Vec2 calc_field_grad(int gidx)
+{
+ int gx = GRID_X(gidx);
+ int gy = GRID_Y(gidx);
+
+ int nidx = ((gx + 1 >= GRID_SIZE ? gx : gx + 1) << GRID_BITS) | gy;
+ int pidx = ((gx > 0 ? gx - 1 : gx) << GRID_BITS) | gy;
+ float dfdx = grid[nidx] - grid[pidx];
+
+ nidx = (gx << GRID_BITS) | (gy + 1 >= GRID_SIZE ? gy : gy + 1);
+ pidx = (gx << GRID_BITS) | (gy > 0 ? gy - 1 : gy);
+ float dfdy = grid[nidx] - grid[pidx];
+
+ return Vec2(dfdx, dfdy);
+}
+
+
+// ---- quad mesh operations ----
static void destroy_quadmesh(QuadMesh *m)
{
p->radius = MASS_TO_RADIUS(mass);
grid_part[gidx] = p;
- add_particle(p, gidx);
+ add_particle(p);
}
}
-static void add_particle(Particle *p, int grid_idx)
+static void add_particle(Particle *p)
{
- int listidx = GRID_IDX_PLIST(grid_idx);
- p->next = plist[listidx];
+ if(plist) plist->prev = p;
+
+ p->next = plist;
p->prev = 0;
- plist[listidx] = p;
+ plist = p;
}
-static void remove_particle(Particle *p, int grid_idx)
+static void remove_particle(Particle *p)
{
- Particle *prev = p->prev;
- Particle *next = p->next;
-
- p->prev = p->next = 0;
- if(next) next->prev = prev;
+ assert(plist->prev == 0);
- if(prev) {
- prev->next = next;
- } else {
- int listidx = GRID_IDX_PLIST(grid_idx);
- plist[listidx] = next;
+ if(plist == p) {
+ assert(p->prev == 0);
+ plist = p->next;
+ }
+ if(p->prev) {
+ p->prev->next = p->next;
}
+ if(p->next) {
+ p->next->prev = p->prev;
+ }
+ p->prev = p->next = 0;
}
// particle allocator
projects / ld42_outofspace / blobdiff