From c7cbd0d288083ad7ae132ac6627cf93ec5b3aed5 Mon Sep 17 00:00:00 2001
From: Sakarias Johansson <sakarias.johansson@goodbyekansas.com>
Date: Sun, 16 Apr 2023 14:32:42 +0200
Subject: =?UTF-8?q?=E2=9C=A8=20Add=20support=20for=20camera=20configuratio?=
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Also decided to not use glam and just do the math myself.
Just didn't want an entire library for such a small thing.
Probably goint to replace Vec3 at some point, just not now.
---
 racer-tracer/src/vec3.rs | 48 +++++++++++++++++++++++++++++-------------------
 1 file changed, 29 insertions(+), 19 deletions(-)

(limited to 'racer-tracer/src/vec3.rs')

diff --git a/racer-tracer/src/vec3.rs b/racer-tracer/src/vec3.rs
index 6877eea..40c8453 100644
--- a/racer-tracer/src/vec3.rs
+++ b/racer-tracer/src/vec3.rs
@@ -1,6 +1,3 @@
-//TODO: Replace this with glam.
-use glam::f32::Vec3 as FVec3;
-
 use std::{fmt, ops};
 
 use serde::Deserialize;
@@ -121,6 +118,35 @@ impl Vec3 {
         let s = 1e-8;
         self.data[0].abs() < s && self.data[1].abs() < s && self.data[2].abs() < s
     }
+
+    fn hamilton_product(a: [f64; 4], e: [f64; 4]) -> [f64; 4] {
+        [
+            a[0] * e[0] - a[1] * e[1] - a[2] * e[2] - a[3] * e[3],
+            a[0] * e[1] + a[1] * e[0] + a[2] * e[3] - a[3] * e[2],
+            a[0] * e[2] - a[1] * e[3] + a[2] * e[0] + a[3] * e[1],
+            a[0] * e[3] + a[1] * e[2] - a[2] * e[1] + a[3] * e[0],
+        ]
+    }
+
+    fn get_rotation(degrees: f64, axis: &Vec3) -> ([f64; 4], [f64; 4]) {
+        let hd = degrees * 0.5;
+        let rot = [
+            hd.cos(),
+            hd.sin() * *axis.x(),
+            hd.sin() * *axis.y(),
+            hd.sin() * *axis.z(),
+        ];
+        (rot, [rot[0], -rot[1], -rot[2], -rot[3]])
+    }
+
+    pub fn rotate(&mut self, degrees: f64, axis: &Vec3) {
+        let p = [0.0, self.data[0], self.data[1], self.data[2]];
+        let (r, r_neg) = Vec3::get_rotation(degrees, axis);
+        let rpr_neg = Vec3::hamilton_product(Vec3::hamilton_product(r, p), r_neg);
+        self.data[0] = rpr_neg[1];
+        self.data[1] = rpr_neg[2];
+        self.data[2] = rpr_neg[3];
+    }
 }
 
 pub fn dot(v1: &Vec3, v2: &Vec3) -> f64 {
@@ -329,22 +355,6 @@ impl fmt::Display for Vec3 {
     }
 }
 
-impl From<FVec3> for Vec3 {
-    fn from(v: FVec3) -> Self {
-        Vec3::new(v.x as f64, v.y as f64, v.z as f64)
-    }
-}
-
-impl From<Vec3> for FVec3 {
-    fn from(v: Vec3) -> Self {
-        FVec3 {
-            x: v.data[0] as f32,
-            y: v.data[1] as f32,
-            z: v.data[2] as f32,
-        }
-    }
-}
-
 impl std::fmt::Debug for Vec3 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("Vec3").field("data", &self.data).finish()
-- 
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