wlroots/include/util/matrix.h

#ifndef UTIL_MATRIX_H
#define UTIL_MATRIX_H

#include <wayland-server-protocol.h>

struct wlr_box;
struct wlr_fbox;

/** mat ← a × b */
void matrix_multiply(float mat[static 9], const float a[static 9],
	const float b[static 9]);

/** Writes a transformation matrix which applies the specified
 *  wl_output_transform to mat */
void matrix_transform(float mat[static 9], enum wl_output_transform transform);

/** Shortcut for the various matrix operations involved in projecting the
 *  specified wlr_box onto a given orthographic projection. The result is
 *  written to mat, which can be applied to each coordinate of the box to get a
 *  new coordinate from [-1,1].
 */
void matrix_project_box(float mat[static 9], const struct wlr_box *box);

void matrix_project_fbox(float mat[static 9], const struct wlr_fbox *box);

/**
 * Writes a 2D orthographic projection matrix to mat of (width, height).
 *
 * Equivalent to glOrtho(0, width, 0, height, 1, -1) with the transform applied.
 */
void matrix_projection(float mat[static 9], int width, int height);

/**
 * Compute the inverse of a matrix.
 *
 * The matrix needs to be inversible.
 */
void matrix_invert(float out[static 9], float m[static 9]);

#endif