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math: add orthographic projection

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Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
This commit is contained in:
Stephen Gutekanst 2023-09-08 17:53:37 -07:00
parent eba9390616
commit 94540a4332
1 changed files with 33 additions and 31 deletions
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64
src/math/mat.zig
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@ -135,6 +135,39 @@ pub fn Mat(
pub inline fn translateScalar(scalar: Vec.T) Matrix { pub inline fn translateScalar(scalar: Vec.T) Matrix {
return translate(Vec.splat(scalar)); return translate(Vec.splat(scalar));
} }
/// Constructs an orthographic projection matrix; an orthogonal transformation matrix
/// which transforms from the given left, right, bottom, and top dimensions into
/// `(-1, +1)` in `(x, y)`, and `(0, +1)` in `z`.
///
/// The near/far parameters denotes the depth (z coordinate) of the near/far clipping
/// plane.
///
/// Returns an orthographic projection matrix.
// TODO: needs tests
pub inline fn ortho(
/// The sides of the near clipping plane viewport
left: f32,
right: f32,
bottom: f32,
top: f32,
/// The depth (z coordinate) of the near/far clipping plane.
near: f32,
far: f32,
) Matrix {
const xx = 2 / (right - left);
const yy = 2 / (top - bottom);
const zz = 1 / (near - far);
const tx = (right + left) / (left - right);
const ty = (top + bottom) / (bottom - top);
const tz = near / (near - far);
return init(
RowVec.init(xx, 0, 0, 0),
RowVec.init(0, yy, 0, 0),
RowVec.init(0, 0, zz, 0),
RowVec.init(tx, ty, tz, 1),
);
}
}, },
else => @compileError("Expected Mat3x3, Mat4x4 found '" ++ @typeName(Matrix) ++ "'"), else => @compileError("Expected Mat3x3, Mat4x4 found '" ++ @typeName(Matrix) ++ "'"),
}; };
@ -143,37 +176,6 @@ pub fn Mat(
// to work with this new Mat approach, swapping f32 for the generic T float type, moving 3x3 // to work with this new Mat approach, swapping f32 for the generic T float type, moving 3x3
// and 4x4 specific functions into the mixin above, writing new tests, etc. // and 4x4 specific functions into the mixin above, writing new tests, etc.
// /// Constructs an orthographic projection matrix; an orthogonal transformation matrix which
// /// transforms from the given left, right, bottom, and top dimensions into -1 +1 in x and y,
// /// and 0 to +1 in z.
// ///
// /// The near/far parameters denotes the depth (z coordinate) of the near/far clipping plane.
// ///
// /// Returns an orthographic projection matrix.
// pub inline fn ortho(
// /// The sides of the near clipping plane viewport
// left: f32,
// right: f32,
// bottom: f32,
// top: f32,
// /// The depth (z coordinate) of the near/far clipping plane.
// near: f32,
// far: f32,
// ) Mat4x4 {
// const xx = 2 / (right - left);
// const yy = 2 / (top - bottom);
// const zz = 1 / (near - far);
// const tx = (right + left) / (left - right);
// const ty = (top + bottom) / (bottom - top);
// const tz = near / (near - far);
// return init(Mat4x4, .{
// xx, 0, 0, 0,
// 0, yy, 0, 0,
// 0, 0, zz, 0,
// tx, ty, tz, 1,
// });
// }
// /// Returns the translation component of the 2D matrix. // /// Returns the translation component of the 2D matrix.
// pub inline fn translation2d(v: Mat3x3) Vec2 { // pub inline fn translation2d(v: Mat3x3) Vec2 {
// return .{ mat.index(v, 8), mat.index(v, 9) }; // return .{ mat.index(v, 8), mat.index(v, 9) };