985db6b604
a macro, which is included in macros.rs and subsequently used to implement swizzle operators in vectors and points
65 lines
2.3 KiB
Rust
65 lines
2.3 KiB
Rust
use std::fs::File;
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use std::io::Write;
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use std::path::Path;
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use std::env;
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use std::string::String;
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/// Generate the name of the swizzle function and what it returns.
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/// NOTE: This function assumes that variables are in ASCII format
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fn gen_swizzle_nth(variables: &'static str, mut i: usize) -> (String, String) {
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let mut swizzle_impl = String::new();
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let mut swizzle = String::new();
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let n = variables.len();
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for _ in 0..n {
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let c = variables.as_bytes()[i%n] as char;
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swizzle.push(c);
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swizzle_impl.push_str(&format!("self.{}, ", c));
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i = i/n;
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}
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(swizzle, swizzle_impl)
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}
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/// This script generates the swizzle operators that are included in macros.rs
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/// NOTE: This function assumes that variables are in ASCII format
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fn gen_swizzle_functions(variables: &'static str) -> String {
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let n = variables.len();
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let vec_type = format!("$vector_type{}", n);
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let mut result = String::new();
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let nn = n.pow(n as u32);
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for i in 0..nn {
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let (swizzle_name, swizzle_impl) = gen_swizzle_nth(variables, i);
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result.push_str(
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&format!(" #[inline] pub fn {0}(&self) -> {2}<$S> {{ {2}::new({1}) }}\n",
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swizzle_name, swizzle_impl, vec_type));
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}
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result
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}
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fn main() {
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// The following scripts generates a macro for building swizzle operators for multidimensional
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// vectors or points.
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let out_dir = env::var("OUT_DIR").unwrap();
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let swizzle_file_path = Path::new(&out_dir).join("swizzle_operator_macro.rs");
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let data = format!(
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"/// Generate glm/glsl style swizzle operators
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macro_rules! impl_swizzle_functions {{
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($vector_type2:ident, $S:ident, xy) => {{
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{xy}
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}};
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($vector_type2:ident, $vector_type3:ident, $S:ident, xyz) => {{
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impl_swizzle_functions!($vector_type2, $S, xy);
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{xyz}
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}};
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($vector_type2:ident, $vector_type3:ident, $vector_type4:ident, $S:ident, xyzw) => {{
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impl_swizzle_functions!($vector_type2, $vector_type3, $S, xyz);
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{xyzw}
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}};
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}}", xy=gen_swizzle_functions("xy"),
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xyz=gen_swizzle_functions("xyz"),
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xyzw=gen_swizzle_functions("xyzw"));
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let mut f = File::create(swizzle_file_path)
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.expect("Unable to create file that defines the swizzle operator macro.");
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f.write_all(data.as_bytes()).expect("Unable to write swizzle operator macro.");
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}
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