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math: remove incorrect perspective/ortho projection implementations

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See https://github.com/hexops/mach/issues/1103

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
This commit is contained in:
Stephen Gutekanst 2023-11-10 14:29:47 -07:00
parent d48690fdca
commit c87ea394db
1 changed files with 35 additions and 60 deletions
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95
src/math/mat.zig
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@ -274,67 +274,42 @@ pub fn Mat(
); );
} }
/// Constructs an orthographic projection matrix; an orthogonal transformation matrix // TODO: mandate negative-Z https://github.com/hexops/mach/issues/1103
/// which transforms from the given left, right, bottom, and top dimensions into // /// Constructs an orthographic projection matrix; an orthogonal transformation matrix
/// `(-1, +1)` in `(x, y)`, and `(0, +1)` in `z`. // /// 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. // /// The near/far parameters denotes the depth (z coordinate) of the near/far clipping
/// // /// plane.
/// Returns an orthographic projection matrix. // ///
// TODO: needs tests // /// Returns an orthographic projection matrix.
pub inline fn ortho( // // TODO: needs tests
/// The sides of the near clipping plane viewport // pub inline fn ortho(
left: f32, // /// The sides of the near clipping plane viewport
right: f32, // left: f32,
bottom: f32, // right: f32,
top: f32, // bottom: f32,
/// The depth (z coordinate) of the near/far clipping plane. // top: f32,
near: f32, // /// The depth (z coordinate) of the near/far clipping plane.
far: f32, // near: f32,
) Matrix { // far: f32,
const xx = 2 / (right - left); // ) Matrix {
const yy = 2 / (top - bottom); // const xx = 2 / (right - left);
const zz = 1 / (near - far); // const yy = 2 / (top - bottom);
const tx = (right + left) / (left - right); // const zz = 1 / (near - far);
const ty = (top + bottom) / (bottom - top); // const tx = (right + left) / (left - right);
const tz = near / (near - far); // const ty = (top + bottom) / (bottom - top);
return init( // const tz = near / (near - far);
&RowVec.init(xx, 0, 0, tx), // return init(
&RowVec.init(0, yy, 0, ty), // &RowVec.init(xx, 0, 0, tx),
&RowVec.init(0, 0, zz, tz), // &RowVec.init(0, yy, 0, ty),
&RowVec.init(0, 0, 0, 1), // &RowVec.init(0, 0, zz, tz),
); // &RowVec.init(0, 0, 0, 1),
} // );
// }
// TODO: add perspective projection matrix
/// Constructs a perspective projection matrix; a perspective transformation matrix
/// which transforms from eye space to clip space.
///
/// The field of view angle `fovy` is the vertical angle in radians.
/// The `aspect` ratio is the ratio of the width to the height of the viewport.
/// The `near` and `far` parameters denote the depth (z coordinate) of the near and far clipping planes.
///
/// Returns a perspective projection matrix.
pub inline fn perspective(
/// The field of view angle in the y direction, in radians.
fovy: f32,
/// The aspect ratio of the viewport's width to its height.
aspect: f32,
/// The depth (z coordinate) of the near clipping plane.
near: f32,
/// The depth (z coordinate) of the far clipping plane.
far: f32,
) Matrix {
const f = 1.0 / std.math.tan(fovy / 2.0);
const zz = (near + far) / (near - far);
const zw = (2.0 * near * far) / (near - far);
return init(
&RowVec.init(f / aspect, 0, 0, 0),
&RowVec.init(0, f, 0, 0),
&RowVec.init(0, 0, zz, -1),
&RowVec.init(0, 0, zw, 0),
);
}
}, },
else => @compileError("Expected Mat3x3, Mat4x4 found '" ++ @typeName(Matrix) ++ "'"), else => @compileError("Expected Mat3x3, Mat4x4 found '" ++ @typeName(Matrix) ++ "'"),
}; };