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#include "stdlib.h"
#include "math.h"
#include <GL/glut.h>
#include "sm.h"
#ifdef _WIN32
#define drand48() ((double)rand()/RAND_MAX)
#define srand48(x) (srand((x)))
#endif
#if !defined(GL_VERSION_1_1) && !defined(GL_VERSION_1_2)
#define glBindTexture glBindTextureEXT
#endif
typedef struct elem {
float x, y, z; /* current position */
float dx, dy, dz; /* displacement */
float size; /* scale factor */
float ts; /* time stamp */
float opacity; /* alpha value */
} elem_t;
typedef struct smoke {
float ox, oy, oz; /* origin */
float dx, dy, dz; /* drift */
int elems;
float intensity;
float min_size;
float max_size;
unsigned texture;
elem_t *elem;
} smoke_t;
void *
new_smoke(float x, float y, float z, float dx, float dy, float dz,
int elems, float intensity, unsigned texture) {
int i;
smoke_t *s = malloc(sizeof(smoke_t));
s->ox = x; s->oy = y, s->oz = z;
s->dx = dx; s->dy = dy; s->dz = dz;
s->min_size = .1f;
s->max_size = 1.0;
s->elems = elems;
s->elem = malloc(sizeof(elem_t)*elems);
for(i = 0; i < elems; i++) {
s->elem[i].ts = (float)i/elems;;
s->elem[i].dx = -drand48()*1.5f;
s->elem[i].dy = drand48()*1.5f;
s->elem[i].dz = drand48()*1.5f;
}
s->intensity = intensity;
s->texture = texture;
return s;
}
void
delete_smoke(void *smoke) {
smoke_t *s = smoke;
free(s->elem);
free(s);
}
void
draw_smoke(void *smoke) {
smoke_t *s = smoke;
int i;
glEnable(GL_BLEND);
glDepthMask(0);
#if 1
glEnable(GL_TEXTURE_2D);
#else
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
#endif
glBindTexture(GL_TEXTURE_2D, s->texture);
for(i = 0; i < s->elems; i++) {
elem_t *e = s->elem+i;
glPushMatrix();
glTranslatef(e->x, e->y, e->z);
glScalef(e->size, e->size, 1.);
glColor4f(s->intensity,s->intensity,s->intensity,e->opacity);
glBegin(GL_QUADS);
glTexCoord2f(0, 0); glVertex3f(-1., -1., -0.);
glTexCoord2f(0, 1); glVertex3f(-1., 1., 0.);
glTexCoord2f(1, 1); glVertex3f( 1., 1., 0.);
glTexCoord2f(1, 0); glVertex3f( 1., -1., -0.);
glEnd();
glPopMatrix();
}
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glDisable(GL_TEXTURE_2D);
glDepthMask(1);
glDisable(GL_BLEND);
}
void
update_smoke(void *smoke, float tick) {
smoke_t *s = smoke;
int i;
for(i = 0; i < s->elems; i++) {
elem_t *e = s->elem+i;
e->ts += tick;
if (e->ts > 1.0) e->ts = 0;
e->x = s->ox + s->dx*e->ts + e->dx*e->ts;
e->y = s->oy + s->dy*e->ts + e->dy*e->ts;
e->z = s->oz + s->dz*e->ts + e->dz*e->ts;
e->size = s->min_size + e->ts*s->max_size;
e->opacity = (1.0-e->ts);
}
}
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