Initial commit

src/engine/camera.c

@@ -0,0 +1,90 @@
+#include "engine/camera.h"
+#include <stdlib.h>
+#include <math.h>
+
+void camera_init(Camera *c, float vp_w, float vp_h) {
+    c->pos = vec2_zero();
+    c->viewport = vec2(vp_w, vp_h);
+    c->bounds_min = vec2_zero();
+    c->bounds_max = vec2(vp_w, vp_h); /* default: one screen */
+    c->smoothing = 5.0f;
+    c->deadzone = vec2(30.0f, 20.0f);
+    c->look_ahead = vec2(40.0f, 0.0f);
+}
+
+void camera_set_bounds(Camera *c, float world_w, float world_h) {
+    c->bounds_min = vec2_zero();
+    c->bounds_max = vec2(world_w, world_h);
+}
+
+void camera_follow(Camera *c, Vec2 target, Vec2 velocity, float dt) {
+    /* Target is the center point we want to follow */
+    Vec2 desired;
+    desired.x = target.x - c->viewport.x * 0.5f;
+    desired.y = target.y - c->viewport.y * 0.5f;
+
+    /* Look-ahead: shift camera in the direction of movement */
+    if (velocity.x > 10.0f)       desired.x += c->look_ahead.x;
+    else if (velocity.x < -10.0f) desired.x -= c->look_ahead.x;
+
+    /* Smooth follow using exponential decay */
+    float t = 1.0f - expf(-c->smoothing * dt);
+    c->pos = vec2_lerp(c->pos, desired, t);
+
+    /* Clamp to world bounds */
+    c->pos.x = clampf(c->pos.x, c->bounds_min.x,
+                       c->bounds_max.x - c->viewport.x);
+    c->pos.y = clampf(c->pos.y, c->bounds_min.y,
+                       c->bounds_max.y - c->viewport.y);
+}
+
+Vec2 camera_world_to_screen(const Camera *c, Vec2 world_pos) {
+    Vec2 screen = vec2_sub(world_pos, c->pos);
+    /* Apply shake offset */
+    screen.x += c->shake_offset.x;
+    screen.y += c->shake_offset.y;
+    return screen;
+}
+
+Vec2 camera_screen_to_world(const Camera *c, Vec2 screen_pos) {
+    return vec2_add(screen_pos, c->pos);
+}
+
+/* ── Screen shake ────────────────────────────────── */
+
+static float randf_sym(void) {
+    /* Random float in [-1, 1] */
+    return ((float)rand() / (float)RAND_MAX) * 2.0f - 1.0f;
+}
+
+void camera_shake(Camera *c, float intensity, float duration) {
+    /* Take the stronger shake if one is already active */
+    if (intensity > c->shake_intensity || c->shake_timer <= 0) {
+        c->shake_intensity = intensity;
+        c->shake_timer = duration;
+    }
+}
+
+void camera_update_shake(Camera *c, float dt) {
+    if (c->shake_timer <= 0) {
+        c->shake_offset = vec2_zero();
+        return;
+    }
+
+    c->shake_timer -= dt;
+
+    /* Decay intensity as shake expires */
+    float t = c->shake_timer > 0 ? c->shake_timer / 0.3f : 0;  /* ~0.3s reference */
+    if (t > 1.0f) t = 1.0f;
+    float current = c->shake_intensity * t;
+
+    /* Random offset, rounded to whole pixels for crisp pixel art */
+    c->shake_offset.x = roundf(randf_sym() * current);
+    c->shake_offset.y = roundf(randf_sym() * current);
+
+    if (c->shake_timer <= 0) {
+        c->shake_timer = 0;
+        c->shake_intensity = 0;
+        c->shake_offset = vec2_zero();
+    }
+}