forked from tas/major_tom
6c4b076c68
WIND directive in .lvl files sets a constant horizontal force (px/s^2) that pushes entities, projectiles, and particles. Positive is rightward. Wind is applied as acceleration in physics_update() (halved on ground), directly to projectile and particle velocities, and as a gentle position drift on flyers. Entities with gravity_scale=0 (drones, spacecraft) are unaffected. Levels default to no wind when the directive is absent.
532 lines
15 KiB
C
532 lines
15 KiB
C
#include "engine/particle.h"
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#include "engine/renderer.h"
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#include "engine/physics.h"
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#include "engine/camera.h"
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#include <stdlib.h>
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#include <math.h>
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#ifndef M_PI
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#define M_PI 3.14159265358979323846
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#endif
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static Particle s_particles[MAX_PARTICLES];
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/* ── Helpers ─────────────────────────────────────────── */
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static float randf(void) {
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return (float)rand() / (float)RAND_MAX;
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}
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static float randf_range(float lo, float hi) {
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return lo + randf() * (hi - lo);
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}
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static uint8_t clamp_u8(int v) {
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if (v < 0) return 0;
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if (v > 255) return 255;
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return (uint8_t)v;
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}
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/* ── Core API ────────────────────────────────────────── */
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void particle_init(void) {
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for (int i = 0; i < MAX_PARTICLES; i++) {
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s_particles[i].active = false;
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}
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}
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static Particle *alloc_particle(void) {
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/* Find a free slot */
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for (int i = 0; i < MAX_PARTICLES; i++) {
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if (!s_particles[i].active) return &s_particles[i];
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}
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/* Steal the oldest (lowest remaining life) */
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float min_life = 1e9f;
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int min_idx = 0;
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for (int i = 0; i < MAX_PARTICLES; i++) {
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if (s_particles[i].life < min_life) {
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min_life = s_particles[i].life;
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min_idx = i;
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}
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}
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return &s_particles[min_idx];
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}
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void particle_emit(const ParticleBurst *b) {
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for (int i = 0; i < b->count; i++) {
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Particle *p = alloc_particle();
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/* Random angle within spread cone */
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float angle = b->direction + randf_range(-b->spread, b->spread);
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float speed = randf_range(b->speed_min, b->speed_max);
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p->pos = b->origin;
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p->vel = vec2(cosf(angle) * speed, sinf(angle) * speed);
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p->life = randf_range(b->life_min, b->life_max);
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p->max_life = p->life;
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p->size = randf_range(b->size_min, b->size_max);
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p->drag = b->drag;
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p->gravity_scale = b->gravity_scale;
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p->active = true;
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/* Color with optional variation */
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p->color = b->color;
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if (b->color_vary) {
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int vary = 30;
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p->color.r = clamp_u8(b->color.r + (int)randf_range(-vary, vary));
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p->color.g = clamp_u8(b->color.g + (int)randf_range(-vary, vary));
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p->color.b = clamp_u8(b->color.b + (int)randf_range(-vary, vary));
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}
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}
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}
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void particle_update(float dt) {
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float gravity = physics_get_gravity();
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float wind = physics_get_wind();
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for (int i = 0; i < MAX_PARTICLES; i++) {
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Particle *p = &s_particles[i];
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if (!p->active) continue;
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p->life -= dt;
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if (p->life <= 0) {
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p->active = false;
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continue;
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}
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/* Apply gravity */
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p->vel.y += gravity * p->gravity_scale * dt;
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/* Apply wind (reuse gravity_scale as environmental-force scale) */
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if (wind != 0.0f && p->gravity_scale > 0.0f) {
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p->vel.x += wind * p->gravity_scale * dt;
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}
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/* Apply drag */
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if (p->drag > 0) {
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float factor = 1.0f - p->drag * dt;
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if (factor < 0) factor = 0;
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p->vel.x *= factor;
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p->vel.y *= factor;
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}
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/* Move */
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p->pos.x += p->vel.x * dt;
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p->pos.y += p->vel.y * dt;
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}
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}
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void particle_render(const Camera *cam) {
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for (int i = 0; i < MAX_PARTICLES; i++) {
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Particle *p = &s_particles[i];
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if (!p->active) continue;
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/* Alpha fade based on remaining life */
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float t = p->life / p->max_life;
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SDL_Color c = p->color;
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c.a = (uint8_t)(t * 255.0f);
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/* Shrink slightly as particle ages */
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float sz = p->size * (0.3f + 0.7f * t);
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if (sz < 0.5f) sz = 0.5f;
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renderer_draw_rect(p->pos, vec2(sz, sz), c, LAYER_PARTICLES, cam);
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}
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}
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void particle_clear(void) {
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for (int i = 0; i < MAX_PARTICLES; i++) {
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s_particles[i].active = false;
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}
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}
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/* ── Presets ─────────────────────────────────────────── */
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void particle_emit_death_puff(Vec2 pos, SDL_Color color) {
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ParticleBurst b = {
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.origin = pos,
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.count = 12,
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.speed_min = 30.0f,
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.speed_max = 100.0f,
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.life_min = 0.2f,
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.life_max = 0.5f,
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.size_min = 1.5f,
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.size_max = 3.5f,
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.spread = (float)M_PI, /* full circle */
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.direction = 0,
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.drag = 3.0f,
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.gravity_scale = 0.3f,
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.color = color,
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.color_vary = true,
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};
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particle_emit(&b);
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}
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void particle_emit_landing_dust(Vec2 pos) {
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ParticleBurst b = {
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.origin = pos,
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.count = 6,
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.speed_min = 20.0f,
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.speed_max = 60.0f,
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.life_min = 0.15f,
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.life_max = 0.35f,
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.size_min = 1.0f,
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.size_max = 2.5f,
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.spread = 0.6f, /* ~35 degrees */
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.direction = -(float)M_PI * 0.5f, /* upward */
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.drag = 4.0f,
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.gravity_scale = 0.0f,
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.color = {180, 170, 150, 255}, /* dusty tan */
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.color_vary = true,
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};
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particle_emit(&b);
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}
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void particle_emit_spark(Vec2 pos, SDL_Color color) {
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ParticleBurst b = {
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.origin = pos,
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.count = 5,
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.speed_min = 40.0f,
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.speed_max = 120.0f,
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.life_min = 0.1f,
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.life_max = 0.25f,
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.size_min = 1.0f,
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.size_max = 2.0f,
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.spread = (float)M_PI,
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.direction = 0,
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.drag = 2.0f,
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.gravity_scale = 0.5f,
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.color = color,
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.color_vary = true,
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};
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particle_emit(&b);
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}
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void particle_emit_jetpack_burst(Vec2 pos, Vec2 dash_dir) {
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/* Exhaust fires opposite to dash direction */
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float exhaust_angle = atan2f(-dash_dir.y, -dash_dir.x);
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/* Big initial burst — hot core (white/yellow) */
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ParticleBurst core = {
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.origin = pos,
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.count = 18,
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.speed_min = 80.0f,
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.speed_max = 200.0f,
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.life_min = 0.15f,
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.life_max = 0.35f,
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.size_min = 2.0f,
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.size_max = 4.0f,
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.spread = 0.5f, /* ~30 degree cone */
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.direction = exhaust_angle,
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.drag = 3.0f,
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.gravity_scale = 0.1f,
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.color = {255, 220, 120, 255}, /* bright yellow */
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.color_vary = true,
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};
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particle_emit(&core);
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/* Outer plume — orange/red, wider spread */
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ParticleBurst plume = {
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.origin = pos,
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.count = 14,
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.speed_min = 50.0f,
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.speed_max = 150.0f,
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.life_min = 0.2f,
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.life_max = 0.45f,
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.size_min = 1.5f,
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.size_max = 3.5f,
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.spread = 0.8f, /* wider cone */
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.direction = exhaust_angle,
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.drag = 2.5f,
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.gravity_scale = 0.2f,
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.color = {255, 120, 40, 255}, /* orange */
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.color_vary = true,
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};
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particle_emit(&plume);
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/* Smoke tail — grey, slow, lingers */
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ParticleBurst smoke = {
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.origin = pos,
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.count = 8,
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.speed_min = 20.0f,
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.speed_max = 60.0f,
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.life_min = 0.3f,
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.life_max = 0.6f,
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.size_min = 2.0f,
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.size_max = 4.5f,
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.spread = 1.0f,
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.direction = exhaust_angle,
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.drag = 4.0f,
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.gravity_scale = -0.1f, /* slight float-up */
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.color = {160, 150, 140, 200}, /* smoke grey */
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.color_vary = true,
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};
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particle_emit(&smoke);
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}
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void particle_emit_jetpack_trail(Vec2 pos, Vec2 dash_dir) {
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/* Continuous trail — fewer particles per frame, same exhaust direction */
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float exhaust_angle = atan2f(-dash_dir.y, -dash_dir.x);
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/* Hot sparks */
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ParticleBurst sparks = {
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.origin = pos,
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.count = 3,
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.speed_min = 60.0f,
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.speed_max = 160.0f,
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.life_min = 0.1f,
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.life_max = 0.25f,
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.size_min = 1.5f,
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.size_max = 3.0f,
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.spread = 0.4f,
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.direction = exhaust_angle,
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.drag = 3.0f,
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.gravity_scale = 0.1f,
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.color = {255, 200, 80, 255}, /* yellow-orange */
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.color_vary = true,
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};
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particle_emit(&sparks);
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/* Smoke wisps */
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ParticleBurst smoke = {
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.origin = pos,
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.count = 2,
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.speed_min = 15.0f,
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.speed_max = 40.0f,
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.life_min = 0.2f,
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.life_max = 0.4f,
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.size_min = 1.5f,
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.size_max = 3.5f,
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.spread = 0.7f,
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.direction = exhaust_angle,
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.drag = 3.5f,
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.gravity_scale = -0.1f,
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.color = {140, 130, 120, 180},
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.color_vary = true,
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};
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particle_emit(&smoke);
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}
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void particle_emit_jetpack_boost_burst(Vec2 pos, Vec2 dash_dir) {
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/* Blue flame accents mixed into the regular jetpack burst */
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float exhaust_angle = atan2f(-dash_dir.y, -dash_dir.x);
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/* Hot blue core — bright electric blue */
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ParticleBurst core = {
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.origin = pos,
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.count = 10,
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.speed_min = 90.0f,
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.speed_max = 220.0f,
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.life_min = 0.15f,
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.life_max = 0.35f,
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.size_min = 2.0f,
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.size_max = 4.5f,
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.spread = 0.4f,
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.direction = exhaust_angle,
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.drag = 2.5f,
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.gravity_scale = 0.05f,
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.color = {80, 160, 255, 255}, /* electric blue */
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.color_vary = true,
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};
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particle_emit(&core);
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/* Outer blue-white flare */
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ParticleBurst flare = {
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.origin = pos,
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.count = 8,
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.speed_min = 40.0f,
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.speed_max = 130.0f,
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.life_min = 0.2f,
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.life_max = 0.4f,
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.size_min = 1.5f,
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.size_max = 3.0f,
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.spread = 0.7f,
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.direction = exhaust_angle,
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.drag = 3.0f,
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.gravity_scale = 0.1f,
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.color = {140, 200, 255, 255}, /* light blue */
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.color_vary = true,
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};
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particle_emit(&flare);
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}
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void particle_emit_jetpack_boost_trail(Vec2 pos, Vec2 dash_dir) {
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/* Continuous blue flame trail while dashing with boost active */
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float exhaust_angle = atan2f(-dash_dir.y, -dash_dir.x);
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/* Blue flame sparks */
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ParticleBurst sparks = {
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.origin = pos,
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.count = 2,
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.speed_min = 50.0f,
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.speed_max = 140.0f,
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.life_min = 0.1f,
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.life_max = 0.25f,
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.size_min = 1.5f,
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.size_max = 3.0f,
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.spread = 0.35f,
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.direction = exhaust_angle,
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.drag = 3.0f,
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.gravity_scale = 0.05f,
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.color = {60, 140, 255, 255}, /* bright blue */
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.color_vary = true,
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};
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particle_emit(&sparks);
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/* Blue-white wisps */
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ParticleBurst wisps = {
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.origin = pos,
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.count = 1,
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.speed_min = 20.0f,
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.speed_max = 50.0f,
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.life_min = 0.15f,
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.life_max = 0.35f,
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.size_min = 2.0f,
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.size_max = 3.5f,
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.spread = 0.5f,
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.direction = exhaust_angle,
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.drag = 3.5f,
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.gravity_scale = -0.05f,
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.color = {160, 210, 255, 200}, /* pale blue */
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.color_vary = true,
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};
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particle_emit(&wisps);
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}
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void particle_emit_jetpack_boost_idle(Vec2 pos, bool facing_left) {
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/* Ambient blue flame simmering from the player's back while boost is
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* active but the player isn't dashing. Exhaust drifts backward and
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* slightly downward — a subtle idle glow effect. */
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float exhaust_angle = facing_left ? 0.0f : (float)M_PI; /* away from facing */
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/* Small blue sparks drifting backward */
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ParticleBurst sparks = {
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.origin = pos,
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.count = 1,
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.speed_min = 15.0f,
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.speed_max = 45.0f,
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.life_min = 0.12f,
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.life_max = 0.3f,
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.size_min = 1.0f,
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.size_max = 2.5f,
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.spread = 0.8f,
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.direction = exhaust_angle,
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.drag = 4.0f,
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.gravity_scale = 0.15f,
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.color = {50, 130, 255, 220}, /* medium blue */
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.color_vary = true,
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};
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particle_emit(&sparks);
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/* Faint blue-white wisps floating up */
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ParticleBurst wisps = {
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.origin = pos,
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.count = 1,
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.speed_min = 8.0f,
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.speed_max = 25.0f,
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.life_min = 0.15f,
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.life_max = 0.35f,
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.size_min = 1.5f,
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.size_max = 2.5f,
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.spread = 1.0f,
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.direction = exhaust_angle - 0.3f, /* slightly upward */
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.drag = 4.5f,
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.gravity_scale = -0.1f,
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.color = {140, 200, 255, 160}, /* pale blue, translucent */
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.color_vary = true,
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};
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particle_emit(&wisps);
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}
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void particle_emit_muzzle_flash(Vec2 pos, Vec2 shoot_dir) {
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float angle = atan2f(shoot_dir.y, shoot_dir.x);
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/* Perpendicular angle for the up/down flare lines */
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float perp = angle + (float)M_PI * 0.5f;
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/* Forward beam flash — bright cyan, fast, tight cone */
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ParticleBurst beam = {
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.origin = pos,
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.count = 5,
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.speed_min = 120.0f,
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.speed_max = 250.0f,
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.life_min = 0.03f,
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.life_max = 0.07f,
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.size_min = 1.5f,
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.size_max = 2.5f,
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.spread = 0.15f, /* very tight forward */
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.direction = angle,
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.drag = 6.0f,
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.gravity_scale = 0.0f,
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.color = {100, 220, 255, 255}, /* cyan */
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.color_vary = true,
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};
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particle_emit(&beam);
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/* Vertical flare — perpendicular lines (up) */
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ParticleBurst flare_up = {
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.origin = pos,
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.count = 3,
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.speed_min = 60.0f,
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.speed_max = 140.0f,
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.life_min = 0.02f,
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.life_max = 0.06f,
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.size_min = 1.0f,
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.size_max = 2.0f,
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.spread = 0.12f,
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.direction = perp,
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.drag = 8.0f,
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.gravity_scale = 0.0f,
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.color = {160, 240, 255, 255}, /* light cyan */
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.color_vary = true,
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};
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particle_emit(&flare_up);
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/* Vertical flare — perpendicular lines (down) */
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ParticleBurst flare_down = flare_up;
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flare_down.direction = perp + (float)M_PI; /* opposite perpendicular */
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particle_emit(&flare_down);
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/* Bright white core — instant pop at barrel */
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ParticleBurst core = {
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.origin = pos,
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.count = 2,
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.speed_min = 5.0f,
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.speed_max = 20.0f,
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.life_min = 0.03f,
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.life_max = 0.06f,
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.size_min = 2.5f,
|
|
.size_max = 4.0f,
|
|
.spread = (float)M_PI, /* all directions, stays near barrel */
|
|
.direction = 0,
|
|
.drag = 10.0f,
|
|
.gravity_scale = 0.0f,
|
|
.color = {200, 255, 255, 255}, /* white-cyan glow */
|
|
.color_vary = false,
|
|
};
|
|
particle_emit(&core);
|
|
}
|
|
|
|
void particle_emit_wall_slide_dust(Vec2 pos, int wall_dir) {
|
|
/* Small dust puffs pushed away from the wall */
|
|
float away_angle = (wall_dir < 0) ? 0.0f : (float)M_PI; /* away from wall */
|
|
|
|
ParticleBurst dust = {
|
|
.origin = pos,
|
|
.count = 2,
|
|
.speed_min = 15.0f,
|
|
.speed_max = 40.0f,
|
|
.life_min = 0.1f,
|
|
.life_max = 0.25f,
|
|
.size_min = 1.0f,
|
|
.size_max = 2.0f,
|
|
.spread = 0.8f,
|
|
.direction = away_angle,
|
|
.drag = 4.0f,
|
|
.gravity_scale = -0.1f, /* slight float-up */
|
|
.color = {180, 170, 150, 200}, /* dusty tan */
|
|
.color_vary = true,
|
|
};
|
|
particle_emit(&dust);
|
|
}
|