+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include "demo.h"
+#include "3dgfx.h"
+#include "screen.h"
+#include "cfgopt.h"
+#include "imago2.h"
+#include "util.h"
+
+#define PCOUNT 4000
+#define MAX_LIFE 6.0f
+#define PALPHA 1.0f
+#define ZBIAS 0.25
+#define DRAG 0.95
+#define FORCE 0.07
+#define FREQ 0.085
+static float wind[] = {-0.0, 0.0, 0.01};
+
+
+struct vec2 {
+ float x, y;
+};
+
+struct vec3 {
+ float x, y, z;
+};
+
+struct particle {
+ float x, y, z;
+ float vx, vy, vz; /* velocity */
+ float r, g, b;
+ float life;
+};
+
+struct emitter {
+ struct particle *plist;
+ int pcount;
+};
+
+struct vfield {
+ struct vec2 pos, size;
+
+ int width, height;
+ int xshift;
+ struct vec2 *v;
+};
+
+
+static int init(void);
+static void destroy(void);
+static void start(long trans_time);
+static void draw(void);
+
+int init_emitter(struct emitter *em, int num, unsigned char *map, int xsz, int ysz);
+void update_particles(struct emitter *em, float dt);
+void draw_particles(struct emitter *em);
+
+int init_vfield_load(struct vfield *vf, const char *fname);
+void vfield_eval(struct vfield *vf, float x, float y, struct vec2 *dir);
+
+
+static struct screen scr = {
+ "greets",
+ init,
+ destroy,
+ start, 0,
+ draw
+};
+
+static struct emitter em;
+static struct vfield vfield;
+static struct g3d_vertex *varr;
+static long start_time;
+
+static float cam_theta, cam_phi = 25;
+static float cam_dist = 3;
+
+struct screen *greets_screen(void)
+{
+ return &scr;
+}
+
+
+static int init(void)
+{
+ int xsz, ysz;
+ unsigned char *pixels;
+
+ if(!(pixels = img_load_pixels("data/greets1.png", &xsz, &ysz, IMG_FMT_GREY8))) {
+ fprintf(stderr, "failed to load particle spawn map\n");
+ return -1;
+ }
+
+ init_emitter(&em, PCOUNT, pixels, xsz, ysz);
+ img_free_pixels(pixels);
+
+ if(!(varr = malloc(PCOUNT * sizeof *varr))) {
+ perror("failed to allocate particle vertex buffer\n");
+ return -1;
+ }
+
+ if(init_vfield_load(&vfield, "data/vfield1") == -1) {
+ return -1;
+ }
+
+ return 0;
+}
+
+static void destroy(void)
+{
+}
+
+static void start(long trans_time)
+{
+ g3d_matrix_mode(G3D_PROJECTION);
+ g3d_load_identity();
+ g3d_perspective(50.0, 1.3333333, 0.5, 100.0);
+
+ start_time = time_msec;
+}
+
+static void update(void)
+{
+ static long prev_msec;
+ static int prev_mx, prev_my;
+ static unsigned int prev_bmask;
+
+ long msec = time_msec - start_time;
+ float dt = (msec - prev_msec) / 1000.0f;
+ prev_msec = msec;
+
+ if(mouse_bmask) {
+ if((mouse_bmask ^ prev_bmask) == 0) {
+ int dx = mouse_x - prev_mx;
+ int dy = mouse_y - prev_my;
+
+ if(dx || dy) {
+ if(mouse_bmask & 1) {
+ cam_theta += dx * 1.0;
+ cam_phi += dy * 1.0;
+
+ if(cam_phi < -90) cam_phi = -90;
+ if(cam_phi > 90) cam_phi = 90;
+ }
+ if(mouse_bmask & 4) {
+ cam_dist += dy * 0.5;
+
+ if(cam_dist < 0) cam_dist = 0;
+ }
+ }
+ }
+ }
+ prev_mx = mouse_x;
+ prev_my = mouse_y;
+ prev_bmask = mouse_bmask;
+
+ update_particles(&em, dt);
+}
+
+static void draw(void)
+{
+ update();
+
+ memset(fb_pixels, 0, fb_width * fb_height * 2);
+
+ g3d_matrix_mode(G3D_MODELVIEW);
+ g3d_load_identity();
+ g3d_translate(0, 0, -cam_dist);
+ if(opt.sball) {
+ g3d_mult_matrix(sball_matrix);
+ } else {
+ g3d_rotate(cam_phi, 1, 0, 0);
+ g3d_rotate(cam_theta, 0, 1, 0);
+ }
+
+ draw_particles(&em);
+
+ swap_buffers(fb_pixels);
+}
+
+
+
+int init_emitter(struct emitter *em, int num, unsigned char *map, int xsz, int ysz)
+{
+ int i, x, y;
+ float aspect = (float)xsz / (float)ysz;
+ struct particle *p;
+
+ if(!(em->plist = malloc(num * sizeof *em->plist))) {
+ return -1;
+ }
+ em->pcount = num;
+
+ p = em->plist;
+ for(i=0; i<num; i++) {
+ do {
+ x = rand() % xsz;
+ y = rand() % ysz;
+ } while(map[y * xsz + x] < 128);
+
+ p->x = (float)x / (float)xsz - 0.5;
+ p->y = -(float)y / (float)xsz + 0.5 / aspect;
+ p->z = ((float)i / (float)num * 2.0 - 1.0) * 0.005;
+ p->r = p->g = p->b = 0.9;
+ p->vx = p->vy = p->vz = 0.0f;
+ p->life = MAX_LIFE;
+ ++p;
+ }
+ return 0;
+}
+
+void update_particles(struct emitter *em, float dt)
+{
+ int i;
+ struct vec2 accel;
+ struct particle *p = em->plist;
+ struct g3d_vertex *v = varr;
+
+ for(i=0; i<em->pcount; i++) {
+ vfield_eval(&vfield, p->x, p->y, &accel);
+ p->x += p->vx * DRAG * dt;
+ p->y += p->vy * DRAG * dt;
+ p->z += p->vz * DRAG * dt;
+ p->vx += (wind[0] + accel.x * FORCE) * dt;
+ p->vy += (wind[1] + accel.y * FORCE) * dt;
+ p->vz += (wind[2] + p->z * ZBIAS) * dt;
+ p->life -= dt;
+ if(p->life < 0.0f) p->life = 0.0f;
+
+ v->x = p->x;
+ v->y = p->y;
+ v->z = p->z;
+ v->w = 1.0f;
+ v->r = v->g = v->b = 200;
+ v->a = cround64(p->life * 255.0 / MAX_LIFE);
+ ++v;
+
+ ++p;
+ }
+}
+
+void draw_particles(struct emitter *em)
+{
+ g3d_enable(G3D_BLEND);
+ g3d_draw(G3D_POINTS, varr, PCOUNT);
+ g3d_disable(G3D_BLEND);
+}
+
+
+int init_vfield_load(struct vfield *vf, const char *fname)
+{
+ FILE *fp;
+ int tmp;
+
+ if(!(fp = fopen(fname, "rb"))) {
+ fprintf(stderr, "failed to open vector field: %s\n", fname);
+ return -1;
+ }
+ if(fread(&vf->width, sizeof vf->width, 1, fp) < 1 ||
+ fread(&vf->height, sizeof vf->height, 1, fp) < 1) {
+ fprintf(stderr, "init_vfield_load: unexpected end of file while reading header\n");
+ fclose(fp);
+ return -1;
+ }
+
+ /* assume xsz is pow2 otherwise fuck you */
+ tmp = vf->width - 1;
+ vf->xshift = 0;
+ while(tmp) {
+ ++vf->xshift;
+ tmp >>= 1;
+ }
+
+ if(!(vf->v = malloc(vf->width * vf->height * sizeof *vf->v))) {
+ fprintf(stderr, "failed to allocate %dx%d vector field\n", vf->width, vf->height);
+ fclose(fp);
+ return -1;
+ }
+ if(fread(vf->v, sizeof *vf->v, vf->width * vf->height, fp) < vf->width * vf->height) {
+ fprintf(stderr, "init_vfield_load: unexpected end of file while reading %dx%d vector field\n",
+ vf->width, vf->height);
+ fclose(fp);
+ return -1;
+ }
+ fclose(fp);
+
+ vf->pos.x = vf->pos.y = 0;
+ vf->size.x = vf->size.y = 1;
+ return 0;
+}
+
+void vfield_eval(struct vfield *vf, float x, float y, struct vec2 *dir)
+{
+ int px, py;
+ float tx, ty;
+ struct vec2 *p1, *p2;
+ struct vec2 left, right;
+
+ x = ((x - vf->pos.x) / vf->size.x + 0.5f) * vf->width;
+ y = ((y - vf->pos.y) / vf->size.y + 0.5f) * vf->height;
+ x = floor(x);
+ y = floor(y);
+
+ if(x < 0) x = 0;
+ if(y < 0) y = 0;
+ if(x > vf->width - 2) x = vf->width - 2;
+ if(y > vf->height - 2) y = vf->height - 2;
+
+ tx = fmod(x, 1.0f);
+ ty = fmod(y, 1.0f);
+
+ px = (int)x;
+ py = (int)y;
+
+ p1 = vf->v + (py << vf->xshift) + px;
+ p2 = p1 + vf->width;
+
+ left.x = p1->x + (p2->x - p1->x) * ty;
+ left.y = p1->y + (p2->y - p1->y) * ty;
+ ++p1;
+ ++p2;
+ right.x = p1->x + (p2->x - p1->x) * ty;
+ right.y = p1->y + (p2->y - p1->y) * ty;
+
+ dir->x = left.x + (right.x - left.x) * tx;
+ dir->y = left.y + (right.y - left.y) * ty;
+
+ dir->x += ((float)rand() / RAND_MAX - 0.5) * 0.7;
+ dir->y += ((float)rand() / RAND_MAX - 0.5) * 0.7;
+}
projects / dosdemo / commitdiff