godot/core/math/projection.h

/**************************************************************************/
/*  projection.h                                                          */
/**************************************************************************/
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/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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#pragma once

#include "core/math/vector3.h"
#include "core/math/vector4.h"

template <typename T>
class Vector;

struct AABB;
struct Plane;
struct Rect2;
struct Transform3D;
struct Vector2;

struct [[nodiscard]] Projection {
	enum Planes {
		PLANE_NEAR,
		PLANE_FAR,
		PLANE_LEFT,
		PLANE_TOP,
		PLANE_RIGHT,
		PLANE_BOTTOM
	};

	Vector4 columns[4] = {
		{ 1, 0, 0, 0 },
		{ 0, 1, 0, 0 },
		{ 0, 0, 1, 0 },
		{ 0, 0, 0, 1 },
	};

	constexpr const Vector4 &operator[](int p_axis) const {
		DEV_ASSERT((unsigned int)p_axis < 4);
		return columns[p_axis];
	}

	constexpr Vector4 &operator[](int p_axis) {
		DEV_ASSERT((unsigned int)p_axis < 4);
		return columns[p_axis];
	}

	real_t determinant() const;
	void set_identity();
	void set_zero();
	void set_light_bias();
	void set_depth_correction(bool p_flip_y = true, bool p_reverse_z = true, bool p_remap_z = true);

	void set_light_atlas_rect(const Rect2 &p_rect);
	void set_perspective(real_t p_fovy_degrees, real_t p_aspect, real_t p_z_near, real_t p_z_far, bool p_flip_fov = false);
	void set_perspective(real_t p_fovy_degrees, real_t p_aspect, real_t p_z_near, real_t p_z_far, bool p_flip_fov, int p_eye, real_t p_intraocular_dist, real_t p_convergence_dist);
	void set_for_hmd(int p_eye, real_t p_aspect, real_t p_intraocular_dist, real_t p_display_width, real_t p_display_to_lens, real_t p_oversample, real_t p_z_near, real_t p_z_far);
	void set_orthogonal(real_t p_left, real_t p_right, real_t p_bottom, real_t p_top, real_t p_znear, real_t p_zfar);
	void set_orthogonal(real_t p_size, real_t p_aspect, real_t p_znear, real_t p_zfar, bool p_flip_fov = false);
	void set_frustum(real_t p_left, real_t p_right, real_t p_bottom, real_t p_top, real_t p_near, real_t p_far);
	void set_frustum(real_t p_size, real_t p_aspect, Vector2 p_offset, real_t p_near, real_t p_far, bool p_flip_fov = false);
	void adjust_perspective_znear(real_t p_new_znear);

	static Projection create_depth_correction(bool p_flip_y);
	static Projection create_light_atlas_rect(const Rect2 &p_rect);
	static Projection create_perspective(real_t p_fovy_degrees, real_t p_aspect, real_t p_z_near, real_t p_z_far, bool p_flip_fov = false);
	static Projection create_perspective_hmd(real_t p_fovy_degrees, real_t p_aspect, real_t p_z_near, real_t p_z_far, bool p_flip_fov, int p_eye, real_t p_intraocular_dist, real_t p_convergence_dist);
	static Projection create_for_hmd(int p_eye, real_t p_aspect, real_t p_intraocular_dist, real_t p_display_width, real_t p_display_to_lens, real_t p_oversample, real_t p_z_near, real_t p_z_far);
	static Projection create_orthogonal(real_t p_left, real_t p_right, real_t p_bottom, real_t p_top, real_t p_znear, real_t p_zfar);
	static Projection create_orthogonal_aspect(real_t p_size, real_t p_aspect, real_t p_znear, real_t p_zfar, bool p_flip_fov = false);
	static Projection create_frustum(real_t p_left, real_t p_right, real_t p_bottom, real_t p_top, real_t p_near, real_t p_far);
	static Projection create_frustum_aspect(real_t p_size, real_t p_aspect, Vector2 p_offset, real_t p_near, real_t p_far, bool p_flip_fov = false);
	static Projection create_fit_aabb(const AABB &p_aabb);
	Projection perspective_znear_adjusted(real_t p_new_znear) const;
	Plane get_projection_plane(Planes p_plane) const;
	Projection flipped_y() const;
	Projection jitter_offseted(const Vector2 &p_offset) const;

	static real_t get_fovy(real_t p_fovx, real_t p_aspect) {
		return Math::rad_to_deg(Math::atan(p_aspect * Math::tan(Math::deg_to_rad(p_fovx) * 0.5)) * 2.0);
	}

	real_t get_z_far() const;
	real_t get_z_near() const;
	real_t get_aspect() const;
	real_t get_fov() const;
	bool is_orthogonal() const;

	Vector<Plane> get_projection_planes(const Transform3D &p_transform) const;

	bool get_endpoints(const Transform3D &p_transform, Vector3 *p_8points) const;
	Vector2 get_viewport_half_extents() const;
	Vector2 get_far_plane_half_extents() const;

	void invert();
	Projection inverse() const;

	constexpr Projection operator*(const Projection &p_matrix) const;

	Plane xform4(const Plane &p_vec4) const;
	_FORCE_INLINE_ Vector3 xform(const Vector3 &p_vec3) const;

	Vector4 xform(const Vector4 &p_vec4) const;
	Vector4 xform_inv(const Vector4 &p_vec4) const;

	operator String() const;

	void scale_translate_to_fit(const AABB &p_aabb);
	void add_jitter_offset(const Vector2 &p_offset);
	void make_scale(const Vector3 &p_scale);
	int get_pixels_per_meter(int p_for_pixel_width) const;
	operator Transform3D() const;

	void flip_y();

	bool is_same(const Projection &p_cam) const;

	constexpr bool operator==(const Projection &p_cam) const {
		for (uint32_t i = 0; i < 4; i++) {
			for (uint32_t j = 0; j < 4; j++) {
				if (columns[i][j] != p_cam.columns[i][j]) {
					return false;
				}
			}
		}
		return true;
	}

	constexpr bool operator!=(const Projection &p_cam) const {
		return !(*this == p_cam);
	}

	real_t get_lod_multiplier() const;

	Projection() = default;
	constexpr Projection(const Vector4 &p_x, const Vector4 &p_y, const Vector4 &p_z, const Vector4 &p_w) :
			columns{ p_x, p_y, p_z, p_w } {}
	constexpr Projection(real_t p_xx, real_t p_xy, real_t p_xz, real_t p_xw, real_t p_yx, real_t p_yy, real_t p_yz, real_t p_yw, real_t p_zx, real_t p_zy, real_t p_zz, real_t p_zw, real_t p_wx, real_t p_wy, real_t p_wz, real_t p_ww) :
			columns{
				{ p_xx, p_xy, p_xz, p_xw },
				{ p_yx, p_yy, p_yz, p_yw },
				{ p_zx, p_zy, p_zz, p_zw },
				{ p_wx, p_wy, p_wz, p_ww },
			} {}
	Projection(const Transform3D &p_transform);
};

constexpr Projection Projection::operator*(const Projection &p_matrix) const {
	Projection new_matrix;

	for (int j = 0; j < 4; j++) {
		for (int i = 0; i < 4; i++) {
			real_t ab = 0;
			for (int k = 0; k < 4; k++) {
				ab += columns[k][i] * p_matrix.columns[j][k];
			}
			new_matrix.columns[j][i] = ab;
		}
	}

	return new_matrix;
}

Vector3 Projection::xform(const Vector3 &p_vec3) const {
	Vector3 ret;
	ret.x = columns[0][0] * p_vec3.x + columns[1][0] * p_vec3.y + columns[2][0] * p_vec3.z + columns[3][0];
	ret.y = columns[0][1] * p_vec3.x + columns[1][1] * p_vec3.y + columns[2][1] * p_vec3.z + columns[3][1];
	ret.z = columns[0][2] * p_vec3.x + columns[1][2] * p_vec3.y + columns[2][2] * p_vec3.z + columns[3][2];
	real_t w = columns[0][3] * p_vec3.x + columns[1][3] * p_vec3.y + columns[2][3] * p_vec3.z + columns[3][3];
	return ret / w;
}