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Add Mars surface atmosphere particels

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Thomas
2026-03-05 19:21:41 +00:00
parent 635869f226
commit 4407932a2d
4 changed files with 85 additions and 5 deletions
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62
src/engine/particle.c
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@@ -529,3 +529,65 @@ void particle_emit_wall_slide_dust(Vec2 pos, int wall_dir) {
};
particle_emit(&dust);
}
/* Spawn a single dust mote with the given visual properties. */
static void spawn_dust_mote(Vec2 pos, Vec2 vel,
float life_min, float life_max,
float size_min, float size_max,
float drag, float gscale,
uint8_t r, uint8_t g, uint8_t b, int vary) {
Particle *p = alloc_particle();
p->pos = pos;
p->vel = vel;
p->life = randf_range(life_min, life_max);
p->max_life = p->life;
p->size = randf_range(size_min, size_max);
p->drag = drag;
p->gravity_scale = gscale;
p->active = true;
p->color.r = clamp_u8(r + (int)randf_range(-vary, vary));
p->color.g = clamp_u8(g + (int)randf_range(-vary, vary));
p->color.b = clamp_u8(b + (int)randf_range(-vary, vary));
p->color.a = 255; /* alpha applied during render from life ratio */
}
void particle_emit_atmosphere_dust(Vec2 cam_pos, Vec2 vp) {
/* Ambient Mars dust — subtle motes drifting across the viewport.
* Two sub-layers for depth: large slow "far" motes and small quick
* "near" specks. Wind carries them; gravity_scale controls how much
* environmental forces (wind + gravity) affect each particle.
* Particles spawn along the upwind viewport edge and drift inward;
* occasional interior spawns prevent a visible edge seam. */
float wind = physics_get_wind();
float margin = 32.0f;
float dir = (wind >= 0.0f) ? 1.0f : -1.0f; /* velocity sign */
/* Upwind edge X for the two edge-spawned layers */
float edge_far = (wind >= 0.0f) ? cam_pos.x - margin
: cam_pos.x + vp.x + margin;
float edge_near = (wind >= 0.0f) ? cam_pos.x - margin * 0.5f
: cam_pos.x + vp.x + margin * 0.5f;
/* Far dust motes — large, slow, translucent (1/frame) */
spawn_dust_mote(
vec2(edge_far, cam_pos.y + randf() * vp.y),
vec2(dir * randf_range(8.0f, 25.0f), randf_range(-6.0f, 6.0f)),
4.0f, 7.0f, 1.5f, 3.0f, 0.3f, 0.08f,
180, 140, 100, 25);
/* Near dust specks — small, quicker, brighter (1/frame) */
spawn_dust_mote(
vec2(edge_near, cam_pos.y + randf() * vp.y),
vec2(dir * randf_range(15.0f, 40.0f), randf_range(-10.0f, 10.0f)),
2.5f, 5.0f, 0.8f, 1.5f, 0.2f, 0.12f,
200, 160, 120, 20);
/* Occasional interior spawn — prevents edge seam on calm wind */
if (rand() % 3 == 0) {
spawn_dust_mote(
vec2(cam_pos.x + randf() * vp.x, cam_pos.y + randf() * vp.y),
vec2(randf_range(-5.0f, 5.0f), randf_range(-8.0f, 3.0f)),
3.0f, 6.0f, 1.0f, 2.5f, 0.4f, 0.06f,
160, 130, 95, 25);
}
}