[dosdemo] / src / hairball.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "demo.h"
#include "3dgfx.h"
#include "vmath.h"
#include "screen.h"
#include "util.h"

#define NSPAWNPOS       128
#define SPAWN_RATE      16.0f
#define GRAV            (-6.0f)
#define HAIR_LENGTH 32

struct particle {
        vec3_t pos;
        vec3_t vel;
        float r, g, b, a;
        int life;

        struct particle *next;
};

struct hairball {
        vec3_t pos;
        quat_t rot;
        float xform[16];

        struct particle *plist[NSPAWNPOS];
};

static int init(void);
static void destroy(void);
static void start(long trans_time);
static void draw(void);
static void update_hairball(struct hairball *hb, float dt);
static void draw_hairball(struct hairball *hb);

static struct particle *palloc(void);
void pfree(struct particle *p);


static struct screen scr = {
        "hairball",
        init,
        destroy,
        start, 0,
        draw
};

static long start_time;

static vec3_t *spawnpos, *spawndir;

static struct hairball hball;

struct screen *hairball_screen(void)
{
        return &scr;
}

static int init(void)
{
        int i;

        hball.xform[0] = hball.xform[5] = hball.xform[10] = hball.xform[15] = 1.0f;
        hball.rot.w = 1.0f;

        if(!(spawnpos = malloc(NSPAWNPOS * sizeof *spawnpos)) ||
                        !(spawndir = malloc(NSPAWNPOS * sizeof *spawndir))) {
                fprintf(stderr, "failed to allocate spawnpos/dir array\n");
                return -1;
        }

        for(i=0; i<NSPAWNPOS; i++) {
                spawnpos[i] = spawndir[i] = sphrand(1.0f);
        }

        return 0;
}

static void destroy(void)
{
}

static void start(long trans_time)
{
        g3d_matrix_mode(G3D_PROJECTION);
        g3d_load_identity();
        g3d_perspective(50.0, 1.33333, 0.5, 100.0);

        start_time = time_msec;
}

static void update(void)
{
        static float prev_mx, prev_my;
        static long prev_msec;
        int mouse_dx, mouse_dy;
        long msec = time_msec - start_time;
        float dt = (msec - prev_msec) / 1000.0f;
        prev_msec = msec;

        mouse_dx = mouse_x - prev_mx;
        mouse_dy = mouse_y - prev_my;
        prev_mx = mouse_x;
        prev_my = mouse_y;

        if(mouse_bmask) {
                hball.pos.x += mouse_dx * 0.05;
                hball.pos.y -= mouse_dy * 0.05;
        }

        hball.rot = quat_rotate(hball.rot, dt * 2.0f, 0, 1, 0);

        quat_to_mat(hball.xform, hball.rot);
        hball.xform[12] = hball.pos.x;
        hball.xform[13] = hball.pos.y;
        hball.xform[14] = hball.pos.z;

        update_hairball(&hball, 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, -8);

        draw_hairball(&hball);

        swap_buffers(fb_pixels);
}

static void update_hairball(struct hairball *hb, float dt)
{
        int i, j, spawn_count;
        struct particle pdummy, *prev, *p;
        static float spawn_acc;

        /* update particles */
        for(i=0; i<NSPAWNPOS; i++) {
                pdummy.next = hb->plist[i];
                prev = &pdummy;
                while(prev && prev->next) {
                        p = prev->next;
                        if(--p->life <= 0) {
                                prev->next = p->next;
                                pfree(p);
                                prev = prev->next;
                                continue;
                        }

                        p->pos.x += p->vel.x * dt;
                        p->pos.y += p->vel.y * dt;
                        p->pos.z += p->vel.z * dt;
                        p->vel.y += GRAV * dt;
                        prev = p;
                }

                hb->plist[i] = pdummy.next;
        }

        /* spawn new particles */
        spawn_acc += dt;
        if(spawn_acc >= (1.0f / SPAWN_RATE)) {
                for(i=0; i<NSPAWNPOS; i++) {
                        struct particle *p = palloc();
                        float *mat = hb->xform;
                        vec3_t pos = spawnpos[i];

                        p->pos.x = mat[0] * pos.x + mat[4] * pos.y + mat[8] * pos.z + mat[12];
                        p->pos.y = mat[1] * pos.x + mat[5] * pos.y + mat[9] * pos.z + mat[13];
                        p->pos.z = mat[2] * pos.x + mat[6] * pos.y + mat[10] * pos.z + mat[14];

                        p->vel = spawndir[i];
                        p->life = HAIR_LENGTH;
                        /* TODO color */

                        p->next = hb->plist[i];
                        hb->plist[i] = p;
                }
                spawn_acc -= 1.0f / SPAWN_RATE;
        }
}

static void draw_hairball(struct hairball *hb)
{
        int i, j, col;
        struct particle *p;
        vec3_t prevpos;

        g3d_begin(G3D_LINES);
        for(i=0; i<NSPAWNPOS; i++) {
                p = hb->plist[i];
                prevpos.x = hb->xform[0] * spawnpos[i].x + hb->xform[4] * spawnpos[i].y + hb->xform[8] * spawnpos[i].z + hb->xform[12];
                prevpos.y = hb->xform[1] * spawnpos[i].x + hb->xform[5] * spawnpos[i].y + hb->xform[9] * spawnpos[i].z + hb->xform[13];
                prevpos.z = hb->xform[2] * spawnpos[i].x + hb->xform[6] * spawnpos[i].y + hb->xform[10] * spawnpos[i].z + hb->xform[14];

                j = 0;
                while(p) {
                        col = 255 - j++ * (HAIR_LENGTH - 1);
                        g3d_color3b(col, col, col);
                        g3d_vertex(prevpos.x, prevpos.y, prevpos.z);
                        g3d_vertex(p->pos.x, p->pos.y, p->pos.z);
                        prevpos = p->pos;
                        p = p->next;
                }
        }
        g3d_end();
}


static struct particle *palloc(void)
{
        return malloc(sizeof(struct particle));
}

void pfree(struct particle *p)
{
        free(p);
}