#include "opengl.h"
#include "texture.h"
#include "sdr.h"
+#include "mesh.h"
+#include "meshgen.h"
/* NOTES:
* - whistle hhgg music
- * - colliding particles merge
* - select objects and center camera on them
*/
float mass;
Vec2 pos;
Vec2 vel;
+
+ float vis_height;
+
+ Particle *next, *prev;
};
struct Emitter {
float mass;
float rate, chunk;
float angle, spread;
+
+ float spawn_pending;
};
struct Rect {
#define SIM_DT 0.016
#define GRID_SIZE 2048
-#define GRID_BITS 12
+#define GRID_BITS 11
#define GRID_X(idx) (((idx) >> GRID_BITS) & (GRID_SIZE - 1))
#define GRID_Y(idx) ((idx) & (GRID_SIZE - 1))
#define GRID_DELTA ((float)FIELD_SIZE / (float)GRID_SIZE)
#define MIN_CAM_DIST 1.0f
#define MAX_CAM_DIST 350.0f
-#define MASS_TO_RAD(m) log((m) + 1.0)
+#define MASS_TO_RADIUS(m) log((m) + 1.0)
#define CONTRIB_THRES 0.005
#define CONTRIB_RANGE(m) sqrt((m) / CONTRIB_THRES)
+/* gravitational strength */
+#define GRAV_STR 16.0f
+
+static int pos_to_grid_x_noclamp(float x);
+static int pos_to_grid_y_noclamp(float y);
static int pos_to_grid(float x, float y);
static Vec2 grid_to_pos(int gx, int gy);
+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);
+static void remove_particle(Particle *p);
+static Particle *alloc_particle();
+void free_particle(Particle *p);
+
+static bool pause;
+
static float grid[GRID_SIZE * GRID_SIZE];
-static Particle grid_part[GRID_SIZE * GRID_SIZE];
+static Particle *grid_part[GRID_SIZE * GRID_SIZE];
static Texture *grid_tex;
+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 Mesh *pmesh;
+static unsigned int particle_sdr;
+
+static Vec2 cam_pos;
static float cam_theta;
static float cam_dist = 100.0f;
-static Vec2 *targ_pos;
+static Vec2 *targ_pos = &cam_pos;
static Mat4 view_matrix, proj_matrix;
+static bool wireframe;
+
// emitter placement data (filled by event handlers, completed in update)
static bool emit_place_pending;
static Vec2 emit_place_pos;
gen_quad_plane(&field_mesh, FIELD_SIZE, FIELD_SIZE, 32, 32);
+ pmesh = new Mesh;
+ gen_geosphere(pmesh, 1.0, 2);
+
+ if(!(particle_sdr = create_program_load("sdr/sph.v.glsl", "sdr/sph.p.glsl"))) {
+ return false;
+ }
+
// XXX DBG
emit_place_pos = Vec2(0, 0);
emit_place_pending = true;
delete gvis_tex;
delete grid_tex;
destroy_quadmesh(&field_mesh);
+ delete pmesh;
}
-static void calc_contrib_bounds(const Emitter *em, Rect *rect)
+static void simstep()
{
- int gidx = pos_to_grid(em->pos.x, em->pos.y);
- int gx = GRID_X(gidx);
- int gy = GRID_Y(gidx);
- int maxrange = (int)ceil(CONTRIB_RANGE(em->mass));
+ if(pause) return;
+
+ // 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) * GRAV_STR;
+
+ p->vel += grad * SIM_DT;
+ p->pos += p->vel * SIM_DT;
+
+ // if it moved outside of the simulation field, remove it
+ int gx = pos_to_grid_x_noclamp(p->pos.x);
+ int gy = pos_to_grid_y_noclamp(p->pos.y);
+ if(gx < 0 || gx >= GRID_SIZE || gy < 0 || gy >= GRID_SIZE) {
+ Particle *next = p->next;
+ grid_part[gidx] = 0;
+ remove_particle(p);
+ free_particle(p);
+ p = next;
+ continue;
+ }
- int sx = gx - maxrange;
- int sy = gy - maxrange;
- int ex = gx + maxrange;
- int ey = gy + maxrange;
+ // 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(ex > GRID_SIZE) ex = GRID_SIZE;
- if(ey > GRID_SIZE) ey = GRID_SIZE;
+ if(gidx_next == gidx) {
+ p = p->next;
+ continue;
+ }
- rect->x = sx < 0 ? 0 : sx;
- rect->y = sy < 0 ? 0 : sy;
- rect->width = ex - sx;
- rect->height = ey - sy;
-}
+ 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;
+ }
-static void simstep()
-{
- // calculate gravitational field - assume field within radius constant: m / r^2
+ p = p->next;
+ }
+ }
- // first clear the field, and then add contributions
- memset(grid, 0, sizeof grid);
+ // TODO destroy particles which left the simulation field
- // contribution of emitters
+ // spawn particles
int num_emitters = emitters.size();
for(int i=0; i<num_emitters; i++) {
Emitter *em = emitters[i];
- Rect cbox;
- calc_contrib_bounds(em, &cbox);
- float emradius = MASS_TO_RAD(em->mass);
-
- float *gptr = grid + cbox.y * GRID_SIZE + cbox.x;
- Vec2 startpos = grid_to_pos(cbox.x, cbox.y);
+ em->spawn_pending += em->rate * SIM_DT;
+ while(em->spawn_pending >= 1.0f && em->mass > 0.0f) {
+ Vec2 pvel; // XXX calc eject velocity
- for(int y=0; y<cbox.height; y++) {
- for(int x=0; x<cbox.width; x++) {
- Vec2 cellpos = Vec2(startpos.x + (float)x * GRID_DELTA, startpos.y);
+ float angle = (float)rand() / (float)RAND_MAX * (M_PI * 2.0);
+ float emradius = MASS_TO_RADIUS(em->mass);
+ Vec2 ppos = em->pos + Vec2(cos(angle), sin(angle)) * emradius * 1.00001;
- Vec2 dir = cellpos - em->pos;
- float dsq = dot(dir, dir);
- float radsq = emradius * emradius;
- if(dsq < radsq) {
- dsq = radsq;
- }
+ float pmass = em->chunk > em->mass ? em->mass : em->chunk;
+ spawn_particle(ppos, pvel, pmass);
+ em->mass -= pmass;
- gptr[x] -= em->mass / dsq;
- }
+ em->spawn_pending -= 1.0f;
+ }
+ }
- startpos.y += GRID_DELTA;
- gptr += GRID_SIZE;
+ // remove dead emitters
+ std::vector<Emitter*>::iterator it = emitters.begin();
+ while(it != emitters.end()) {
+ Emitter *em = *it;
+
+ if(em->mass <= 0.0f) {
+ printf("emitter depleted\n");
+ it = emitters.erase(it);
+ delete em;
+ } else {
+ it++;
}
}
+ // 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 emitters
+ for(int i=0; i<num_emitters; i++) {
+ Emitter *em = emitters[i];
+ Rect cbox;
+ calc_contrib_bounds(em->pos, em->mass, &cbox);
+ float emradius = MASS_TO_RADIUS(em->mass);
+
+ add_influence(em->pos, -em->mass, emradius, cbox);
+ }
+
+ // contribution of particles
+ 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
assert(glGetError() == GL_NO_ERROR);
grid_tex->bind();
Emitter *em = new Emitter;
em->pos = emit_place_pos;
em->mass = 100;
- em->rate = 1;
- em->chunk = 0.05;
+ em->rate = 10;
+ em->chunk = 0.001 * em->mass;
em->angle = -1;
em->spread = 0;
+ em->spawn_pending = 0;
emitters.push_back(em);
Rect cbox;
- calc_contrib_bounds(em, &cbox);
+ calc_contrib_bounds(em->pos, em->mass, &cbox);
printf("bounds: %d,%d %dx%d\n", cbox.x, cbox.y, cbox.width, cbox.height);
}
glMatrixMode(GL_MODELVIEW);
glLoadMatrixf(view_matrix[0]);
- glPushAttrib(GL_ENABLE_BIT);
- glDisable(GL_LIGHTING);
- glDisable(GL_CULL_FACE);
+ // draw gravitational field
+ if(wireframe) {
+ glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+
+ float amb[] = {0.5, 0.5, 0.5, 1.0};
+ glLightModelfv(GL_LIGHT_MODEL_AMBIENT, amb);
+ } else {
+ float amb[] = {0.01, 0.01, 0.01, 1.0};
+ glLightModelfv(GL_LIGHT_MODEL_AMBIENT, amb);
+ }
- glEnable(GL_TEXTURE_2D);
bind_texture(gvis_tex, 0);
bind_texture(grid_tex, 1);
glUseProgram(field_sdr);
- assert(glGetError() == GL_NO_ERROR);
-
glPatchParameteri(GL_PATCH_VERTICES, 4);
draw_quadmesh(&field_mesh, GL_PATCHES);
- glUseProgram(0);
+ if(wireframe) {
+ glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
+ }
- glPopAttrib();
+ // draw particles
+ glUseProgram(particle_sdr);
+
+ Particle *p = plist;
+ while(p) {
+ int gidx = pos_to_grid(p->pos.x, p->pos.y);
+
+ glPushMatrix();
+ glTranslatef(p->pos.x, p->vis_height, p->pos.y);
+ glScalef(p->radius, p->radius, p->radius);
+
+ pmesh->draw();
+
+ glPopMatrix();
+ p = p->next;
+ }
+
+ glUseProgram(0);
assert(glGetError() == GL_NO_ERROR);
}
set_uniform_float(field_sdr, "field_scale", field_scale);
break;
+ case 'w':
+ wireframe = !wireframe;
+ break;
+
+ case ' ':
+ pause = !pause;
+ break;
+
default:
break;
}
prev_x = x;
prev_y = y;
+ if(game_bnstate(0)) {
+ float pan_speed = pow(cam_dist, 1.5) * 0.00035; // magic
+ Vec2 dir = rotate(Vec2(dx, dy) * pan_speed, deg_to_rad(cam_theta));
+ cam_pos.x -= dir.x;
+ cam_pos.y -= dir.y;
+ }
+
if(game_bnstate(2)) {
cam_theta += dx * 0.5;
}
if(cam_dist > MAX_CAM_DIST) cam_dist = MAX_CAM_DIST;
}
+static int pos_to_grid_x_noclamp(float x)
+{
+ return ((x / (float)FIELD_SIZE) + 0.5f) * (float)GRID_SIZE;
+}
+
+static int pos_to_grid_y_noclamp(float y)
+{
+ return ((y / (float)FIELD_SIZE) + 0.5f) * (float)GRID_SIZE;
+}
static int pos_to_grid(float x, float y)
{
- int gx = ((x / (float)FIELD_SIZE) + 0.5f) * (float)GRID_SIZE;
- int gy = ((y / (float)FIELD_SIZE) + 0.5f) * (float)GRID_SIZE;
+ int gx = pos_to_grid_x_noclamp(x);
+ int gy = pos_to_grid_y_noclamp(y);
if(gx < 0) gx = 0;
if(gx >= GRID_SIZE) gx = GRID_SIZE - 1;
return Vec2(x, y);
}
+static void calc_contrib_bounds(const Vec2 &pos, float mass, Rect *rect)
+{
+ int gidx = pos_to_grid(pos.x, pos.y);
+ int gx = GRID_X(gidx);
+ int gy = GRID_Y(gidx);
+ int maxrange = (int)ceil(CONTRIB_RANGE(mass));
+
+ int sx = gx - maxrange;
+ int sy = gy - maxrange;
+ int ex = gx + maxrange;
+ int ey = gy + maxrange;
+
+ if(ex > GRID_SIZE) ex = GRID_SIZE;
+ if(ey > GRID_SIZE) ey = GRID_SIZE;
+
+ rect->x = sx < 0 ? 0 : sx;
+ rect->y = sy < 0 ? 0 : sy;
+ rect->width = ex - sx;
+ rect->height = ey - sy;
+}
+
+static void add_influence(const Vec2 &pos, float mass, float radius, const Rect &cbox)
+{
+ float *gptr = grid + cbox.y * GRID_SIZE + cbox.x;
+ Vec2 startpos = grid_to_pos(cbox.x, cbox.y);
+
+ for(int y=0; y<cbox.height; y++) {
+ for(int x=0; x<cbox.width; x++) {
+ Vec2 cellpos = Vec2(startpos.x + (float)x * GRID_DELTA, startpos.y);
+
+ Vec2 dir = cellpos - pos;
+ float dsq = dot(dir, dir);
+ float radsq = radius * radius;
+ if(dsq < radsq) {
+ dsq = radsq;
+ }
+
+ gptr[x] += mass / dsq;
+ }
+
+ startpos.y += GRID_DELTA;
+ gptr += GRID_SIZE;
+ }
+}
+
+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)
{
glDeleteBuffers(1, &m->vbo_v);
int idx = i * vverts + j;
*iptr++ = idx;
- *iptr++ = idx + vverts;
- *iptr++ = idx + vverts + 1;
*iptr++ = idx + 1;
+ *iptr++ = idx + vverts + 1;
+ *iptr++ = idx + vverts;
}
v += dv;
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
}
+
+static void spawn_particle(const Vec2 &pos, const Vec2 &vel, float mass)
+{
+ int gidx = pos_to_grid(pos.x, pos.y);
+
+ if(grid_part[gidx]) {
+ // merge with existing
+ Particle *p = grid_part[gidx];
+ p->vel += vel;
+ p->mass += mass;
+ p->radius = MASS_TO_RADIUS(p->mass);
+
+ } else {
+ Particle *p = alloc_particle();
+ p->pos = pos;
+ p->vel = vel;
+ p->mass = mass;
+ p->radius = MASS_TO_RADIUS(mass);
+ grid_part[gidx] = p;
+
+ add_particle(p);
+ }
+}
+
+static void add_particle(Particle *p)
+{
+ if(plist) plist->prev = p;
+
+ p->next = plist;
+ p->prev = 0;
+ plist = p;
+}
+
+static void remove_particle(Particle *p)
+{
+ assert(plist->prev == 0);
+
+ 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
+#define MAX_PFREE_SIZE 256
+static Particle *pfree_list;
+static int pfree_size;
+
+static Particle *alloc_particle()
+{
+ if(pfree_list) {
+ Particle *p = pfree_list;
+ pfree_list = pfree_list->next;
+ pfree_size--;
+ return p;
+ }
+
+ return new Particle;
+}
+
+void free_particle(Particle *p)
+{
+ if(pfree_size < MAX_PFREE_SIZE) {
+ p->next = pfree_list;
+ p->prev = 0;
+ pfree_list = p;
+ pfree_size++;
+ } else {
+ delete p;
+ }
+}
projects / ld42_outofspace / blobdiff