// sand_sim.h
#ifndef SAND_SIM_H
#define SAND_SIM_H

#include <stdbool.h>
#include "glad/glad.h"

// Simple binary sand vs air simulation
typedef struct {
    int gridW;
    int gridH;
    GLuint tex_curr;
    GLuint tex_next;
    GLuint tex_claim;  // NEW: claim buffer
    GLuint prog_sim;
    GLuint prog_paint;
    GLuint prog_relax;
} SandSim;


// Initialize sim, allocate textures, upload initial state, load compute shader.
// Returns true on success, false on failure.
bool sand_init(SandSim* sim, int gridW, int gridH, const char* computeShaderPath);

// Advance simulation by 1 discrete tick (one CA step).
void sand_step_gpu(SandSim* sim);
void sand_relax_gpu(SandSim* sim);
// Destroy all GL objects owned by the sim.
void sand_destroy(SandSim* sim);
void sand_paint_gpu(SandSim* sim,
                    float brushX,
                    float brushY,
                    float brushRadius,
                    int mode);
#endif // SAND_SIM_H