Initial commit

src/engine/parallax.h

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+#ifndef JNR_PARALLAX_H
+#define JNR_PARALLAX_H
+
+#include <SDL2/SDL.h>
+#include <stdbool.h>
+#include "config.h"
+
+/* Forward declarations */
+typedef struct Camera Camera;
+
+/* A single parallax layer */
+typedef struct ParallaxLayer {
+    SDL_Texture *texture;       /* the background image               */
+    int          tex_w, tex_h;  /* texture dimensions in pixels       */
+    float        scroll_x;      /* horizontal scroll factor (0=fixed, 1=full) */
+    float        scroll_y;      /* vertical scroll factor             */
+    bool         active;        /* whether this layer is in use       */
+    bool         owns_texture;  /* true if we generated it (must free) */
+} ParallaxLayer;
+
+/* Parallax background system — up to two layers */
+typedef struct Parallax {
+    ParallaxLayer far_layer;    /* distant background (stars)         */
+    ParallaxLayer near_layer;   /* mid-ground background (nebula)     */
+} Parallax;
+
+/* Initialize parallax (zeroes everything) */
+void parallax_init(Parallax *p);
+
+/* Set a layer from an existing texture (loaded via assets) */
+void parallax_set_far(Parallax *p, SDL_Texture *tex, float scroll_x, float scroll_y);
+void parallax_set_near(Parallax *p, SDL_Texture *tex, float scroll_x, float scroll_y);
+
+/* Generate procedural starfield texture (far layer) */
+void parallax_generate_stars(Parallax *p, SDL_Renderer *renderer);
+
+/* Generate procedural nebula/dust texture (near layer) */
+void parallax_generate_nebula(Parallax *p, SDL_Renderer *renderer);
+
+/* Render both layers (call before tile/entity rendering) */
+void parallax_render(const Parallax *p, const Camera *cam, SDL_Renderer *renderer);
+
+/* Free generated textures (not file-loaded ones — asset manager owns those) */
+void parallax_free(Parallax *p);
+
+#endif /* JNR_PARALLAX_H */