use tiled atlas texture sampling, increase shader speed using inv sqrt

pxl8d/src/math.rs

@@ -1,8 +1,43 @@
 use core::ops::{Add, Mul, Sub};
 
-use crate::pxl8::pxl8_vec3;
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct Vec2 {
+    pub x: f32,
+    pub y: f32,
+}
 
-pub type Vec3 = pxl8_vec3;
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct Vec3 {
+    pub x: f32,
+    pub y: f32,
+    pub z: f32,
+}
+
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct Vec4 {
+    pub x: f32,
+    pub y: f32,
+    pub z: f32,
+    pub w: f32,
+}
+
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct Mat4 {
+    pub m: [f32; 16],
+}
+
+#[allow(non_camel_case_types)]
+pub type pxl8_vec2 = Vec2;
+#[allow(non_camel_case_types)]
+pub type pxl8_vec3 = Vec3;
+#[allow(non_camel_case_types)]
+pub type pxl8_vec4 = Vec4;
+#[allow(non_camel_case_types)]
+pub type pxl8_mat4 = Mat4;
 
 pub const VEC3_ZERO: Vec3 = Vec3 { x: 0.0, y: 0.0, z: 0.0 };
 pub const VEC3_Y: Vec3 = Vec3 { x: 0.0, y: 1.0, z: 0.0 };