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/**********************************************************************
*
* Simply vector/matrix graphic utility
*
* Copyright (c) 2021 Dario Deledda. All rights reserved.
* Use of this source code is governed by an MIT license
* that can be found in the LICENSE file.
*
* TODO:
**********************************************************************/
module m4
import math
// Translate degrees to radians
[inline]
pub fn rad(deg f32) f32 {
return (math.pi / 180.0) * deg
}
// Translate radians to degrees
[inline]
pub fn deg(grad f32) f32 {
return (180.0 / math.pi) * grad
}
// calculate the Orthographic projection matrix
pub fn ortho(left f32, right f32, bottom f32, top f32, z_near f32, z_far f32) Mat4 {
rml := right - left
rpl := right + left
tmb := top - bottom
tpb := top + bottom
fmn := z_far - z_near
fpn := z_far + z_near
if fmn != 0 {
return Mat4{ e: [
2 / rml, 0 , 0, -(rpl / rml),
0 , 2 / tmb, 0, -(tpb / tmb),
0 , 0, 2 / fmn, -(fpn / fmn),
0 , 0, 0, 1,
]!
}
}
return Mat4{ e: [
2 / rml, 0 , 0, -(rpl / rml),
0 , 2 / tmb, 0, -(tpb / tmb),
0 , 0, 0, 0,
0 , 0, 0, 1,
]!
}
}
// Calculate the perspective matrix using (fov:fov, ar:aspect_ratio ,n:near_pane, f:far_plane) as parameters
pub fn perspective(fov f32, ar f32, n f32, f f32) Mat4 {
ctan := f32(1.0 / math.tan(fov * (f32(math.pi) / 360.0))) // for the FOV we use 360 instead 180
return Mat4{ e: [
ctan / ar, 0, 0, 0,
0, ctan, 0, 0,
0, 0, (n + f) / (n - f), -1.0,
0, 0, (2.0 * n * f) / (n - f), 0,
]!
}
}
// Calculate the look-at matrix
pub fn look_at(eye Vec4, center Vec4, up Vec4) Mat4 {
f := (center - eye).normalize3()
s := (f % up).normalize3()
u := (s % f)
return Mat4{ e: [
/* [0][0] */ s.e[0],
/* [0][1] */ u.e[0],
/* [0][2] */ - f.e[0],
/* [0][3] */ 0,
/* [1][1] */ s.e[1],
/* [1][1] */ u.e[1],
/* [1][2] */ - f.e[1],
/* [1][3] */ 0,
/* [2][0] */ s.e[2],
/* [2][1] */ u.e[2],
/* [2][2] */ - f.e[2],
/* [2][3] */ 0,
/* [3][0] */ - (s * eye),
/* [3][1] */ - (u * eye),
/* [3][2] */ f * eye,
/* [3][3] */ 1,
]!
}
}
// Get the complete transformation matrix for GLSL demos
pub fn calc_tr_matrices(w f32, h f32, rx f32, ry f32, in_scale f32) Mat4 {
proj := perspective(60, w / h, 0.01, 10.0)
view := look_at(Vec4{ e: [f32(0.0), 1.5, 6, 0]! }, Vec4{ e: [f32(0), 0, 0, 0]! }, Vec4{ e: [f32(0), 1.0, 0, 0]! })
view_proj := view * proj
rxm := rotate(rad(rx), Vec4{ e: [f32(1), 0, 0, 0]! })
rym := rotate(rad(ry), Vec4{ e: [f32(0), 1, 0, 0]! })
model := rym * rxm
scale_m := scale(Vec4{ e: [in_scale, in_scale, in_scale, 1]! })
res := (scale_m * model) * view_proj
return res
}
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