buffer.h

#ifndef buffer_H
#define buffer_H

#include <gl.h>
#include <stddef.h> // size_t, for the GL-name pools below

typedef int PBindex;

typedef enum Bwhich {
    current = 0,
    other = 1,
    screen = 2
} Bwhich;

typedef struct format {
    GLint format;
    GLint iformat;
} format;

#define BE_1D \
    (format) { .format = GL_RED, .iformat = GL_R32F }
#define BE_2D \
    (format) { .format = GL_RG, .iformat = GL_RG32F }
#define BE_3D \
    (format) { .format = GL_RGB, .iformat = GL_RGB32F }
#define BE_4D \
    (format) { .format = GL_RGBA, .iformat = GL_RGBA32F }

// Growable GL-name array (nob.h's dynamic-array layout, so nob_da_append works on it).
typedef struct GLuintArray {
    GLuint *items;
    size_t count;
    size_t capacity;
} GLuintArray;

typedef struct Buffer {
    const char *name;
    PBindex current;
    PBindex other;
    int width;
    int height;
    GLuint minmag_filter;
    GLuint wrap_st;
    format dim;
    // Pointers to the pools, not into them: the pools grow as each sim claims its slots, and a
    // realloc moves the items. The pool structs themselves have stable addresses.
    const GLuintArray *textures;
    const GLuintArray *framebuffers;
} Buffer;

void buffer_allocate(Buffer *b, const Bwhich which, const PBindex index, const int width, const int height, const char *data);
void buffer_reallocate(Buffer *b, const Bwhich which, const int width, const int height);
void buffer_flip(Buffer *b);
void buffer_bind(Buffer *b, const Bwhich which);
void buffer_update(Buffer *b);                // draw a fullscreen quad (4-vertex triangle strip)
void buffer_update_n(Buffer *b, const int P); // draw P points

#endif /* buffer_H */