view matrices

view matrices.c

t_mat4				classic_mat4_pers_proj(float width, float height)
{
	float			aspect;
	float			znear;
	float			zfar;

	aspect = width / height;
	znear = 0.1f;
	zfar = 1000.f;
	return (mat4_pers_proj(60.f, aspect, znear, zfar));
}

t_mat4				mat4_pers_proj(float fov, float ar, float near, float far)
{
	t_mat4			mat;
	float			xymax;
	float			width;
	float			height;
	float			depth;

	xymax = near * tan(fov * M_PI / 360);
	width = xymax + xymax;
	height = xymax + xymax;
	depth = far - near;
	ft_bzero(mat.m, sizeof(mat.m));
	mat.m[0] = (2.f * near / width) / ar;
	mat.m[5] = 2.f * near / height;
	mat.m[10] = -(far + near) / depth;
	mat.m[11] = -1.f;
	mat.m[14] = -2.f * (far * near) / depth;
	return (mat);
}

t_mat4				mat4_view_lookat(t_vec3 eye, t_vec3 targ, t_vec3 up)
{
	t_mat4		out;
	t_vec3		zaxis;
	t_vec3		xaxis;
	t_vec3		yaxis;

	zaxis = vec3_normal(vec3_sub(eye, targ));
	xaxis = vec3_normal(vec3_cross(up, zaxis));
	yaxis = vec3_cross(zaxis, xaxis);
	out = mat4_ident();
	out.m[0] = xaxis.x;
	out.m[1] = yaxis.x;
	out.m[2] = zaxis.x;
	out.m[4] = xaxis.y;
	out.m[5] = yaxis.y;
	out.m[6] = zaxis.y;
	out.m[8] = xaxis.z;
	out.m[9] = yaxis.z;
	out.m[10] = zaxis.z;
	out.m[12] = -vec3_dot(xaxis, eye);
	out.m[13] = -vec3_dot(yaxis, eye);
	out.m[14] = -vec3_dot(zaxis, eye);
	return (out);
}