/*
 * DESCRIPTION:
 * Texture atlas functions.
*/

#include "atlas.h"

/* Initializes an atlas. */
void
atlas_init(struct Atlas* self, struct Texture texture, s32 frameW, s32 frameH, s32 rows, s32 cols)
{
	self->texture = texture;
	self->frameW = frameW;
	self->frameH = frameH;
	self->rows = rows;
	self->cols = cols;

	self->index = 0;
}

/* Obtains the texture coordinates for an atlas frame. */
void
atlas_uv_get(struct Atlas* self, vec2 uvMin, vec2 uvMax)
{
	vec2 pos;
	s32 col;
	s32 row;

	pos[0] = (f32)(self->index / self->rows) * self->frameW;
	pos[1] = (f32)(self->index % self->rows) * self->frameH;

	uvMin[0] = (f32)pos[0] / self->texture.w;
	uvMin[1] = (f32)pos[1] / self->texture.h;
	uvMax[0] = (f32)(pos[0] + self->frameW) / self->texture.w;
	uvMax[1] = (f32)(pos[1] + self->frameH) / self->texture.h;
}