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120 lines
3.0 KiB
Rust
120 lines
3.0 KiB
Rust
/** Rearrange the rows of a matrix by the given row identifiers
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# Arguments
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* `mat`: the matrix to manipulate
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* `i...`: variadic comma-seperated list of row selectors. The row selectors are each one of:
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* const expression representing the row index of the input to copy. eg: `0` or `2`
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* a letter representing the same. you can use `r,g,b,a` or `x,y,z,w` to represent index 0 through 3,
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or `u,v` to represent indices 0 through 1.
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* an expression in curly braces, representing a value to be copied to an entire row of
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the result, eg: `{1.0}` or `{5}`
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note that the number of selectors doesnt need to match the height of the input!
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# Examples
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```
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# use vector_victor::{swizzle, Vector};
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let myvec = Vector::vec([0, 1, 2, 3]);
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// each element can be selected with:
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// 0: r, x, u, or 0
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// 1: g, y, v, or 1
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// 2: b, z, or 2
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// 3: a, w, or 3
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// or a result row can be filled by a new value
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assert_eq!(swizzle!(myvec, a, z, v, 0, {7}), Vector::vec([3, 2, 1, 0, 7]));
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```
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More often you wont mix and match selector "flavors".
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This example unpacks a [DXT5nm](http://wiki.polycount.com/wiki/Normal_Map_Compression) color
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into the red and green channels, with blue filled with 0.
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```
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# use vector_victor::{swizzle, Vector};
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let myvec = Vector::vec([0, 120, 0, 255]);
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assert_eq!(swizzle!(myvec, a, g, {0}), Vector::vec([255, 120, 0]));
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``` */
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#[macro_export]
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macro_rules! swizzle {
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($mat: expr, $( $i:tt),+) => {{
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let mut result = $mat.permute_rows(&$crate::Vector::vec([$( $crate::get!($mat, $i), )+]));
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let mut _p = 0usize;
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$(
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$crate::sub_literal!(result, _p, $i);
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_p += 1;
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)+
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result
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}};
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}
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#[doc(hidden)]
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#[macro_export]
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macro_rules! get {
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($mat:expr, x) => {
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0usize
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};
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($mat:expr, y) => {
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1usize
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};
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($mat:expr, z) => {
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2usize
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};
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($mat:expr, w) => {
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3usize
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};
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($mat:expr, r) => {
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0usize
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};
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($mat:expr, g) => {
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1usize
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};
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($mat:expr, b) => {
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2usize
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};
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($mat:expr, a) => {
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3usize
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};
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($mat:expr, u) => {
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0usize
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};
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($mat:expr, v) => {
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1usize
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};
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($mat:expr, {$i:expr}) => {
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0usize /* will be replaced later */
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};
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($mat:expr, $i:expr) => {
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$i
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};
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}
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#[doc(hidden)]
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#[macro_export]
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macro_rules! sub_literal {
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($result:expr, $p:expr, {$i:expr}) => {
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$result.set_row($p, &$crate::Vector::fill($i))
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};
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($result:expr, $p:expr, $i:expr) => {};
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}
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#[cfg(test)]
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mod tests {
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use crate::Matrix;
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#[test]
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fn test_swizzle() {
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let identity = Matrix::<i32, 4, 4>::identity();
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assert_eq!(
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swizzle!(identity, a, x, b, (1 + 0), { 2 - 3 }),
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Matrix::mat([
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[0, 0, 0, 1], // a
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[1, 0, 0, 0], // x
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[0, 0, 1, 0], // b
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[0, 1, 0, 0], // row 1
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[-1, -1, -1, -1] // fill(-1)
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])
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);
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}
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}
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