extern "C" {

#include <lua.h>

#include <lauxlib.h>

#include <lextlib.h>

#include <lextlib_lua52.h>

}

#include <lunar.hpp>

#include "matrix.hpp"

static float deg2rad(float deg) {

return deg * M_PI / 180.0f;

}

#if 0

static Eigen::Matrix4f projection(float r, float l, float t, float b, float f, float n) {

const float w = r-l, h = t-b, d = f-n; // width, height, depth

Eigen::Matrix4f projection;

projection <<

2.0f*n/w , 0.0f , (r+l)/w , 0.0f,

0.0f , 2.0f*n/h , (t+b)/h , 0.0f,

0.0f , -(f+n)/d , -2.0f*f*n/d , 0.0f,

0.0f , 0.0f , 1.0f , 0.0f;

return projection;

}

static Eigen::Matrix4f simple_projection(float fovy, float aspect, float n, float f) {

const float

y_scale = tanf(deg2rad(fovy / 2.0f)),

x_scale = aspect * y_scale;

const float

r = y_scale * n,

t = x_scale * n;

return projection(r, -r, t, -t, f, n);

}

#endif

static Eigen::Matrix4f more_simple_projection(float fovy, float aspect, float n, float f) {

const float

y_scale = 1.0f/tanf(deg2rad(fovy / 2.0f)),

x_scale = y_scale / aspect,

d = f - n;

Eigen::Matrix4f out;

out <<

x_scale, 0.0f, 0.0f, 0.0f,

0.0f, y_scale, 0.0f, 0.0f,

0.0f, 0.0f, -((f + n) / d), -((2.0f*n*f)/d),

0.0f, 0.0f, -1.0f, 0.0f;

return out;

}

static int create_projection(lua_State *L) {

using LuaEigen::Matrix4f;

const int l_args = 1;

luaL_checktype(L, l_args, LUA_TTABLE);

lua_getfield(L, l_args, "fovy"); // [-0,+1,e]

float fovy = luaX_checknumber(L, -1, "fovy");

lua_getfield(L, l_args, "aspect"); // [-0,+1,e]

float aspect = luaX_checknumber(L, -1, "aspect");

lua_getfield(L, l_args, "near"); // [-0,+1,e]

float near = luaX_checknumber(L, -1, "near");

lua_getfield(L, l_args, "far"); // [-0,+1,e]

float far = luaX_checknumber(L, -1, "far");

Lunar<Matrix4f>::push(L, new Matrix4f(more_simple_projection(fovy, aspect, near, far)), true);

return 1;

}

static luaL_Reg eigen_util_lib[] = {

LUAX_FUNCTION(, create_projection),

{NULL, NULL}

};

extern "C" int luaopen_eigen_util(lua_State *L) {

luaL_newlib(L, eigen_util_lib);

return 1;

}