From 175c71637b6bea6dcdd0faf3d614339983809bb1 Mon Sep 17 00:00:00 2001
From: vimene <vincent.menegaux@gmail.com>
Date: Thu, 15 Jan 2026 05:15:59 +0100
Subject: rewrote entirely the triangle clipping algorithm
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There is still a lot of work needed to refactor it properly.

- use the Sutherland–Hodgman algorithm, with some minor changes
- made clipping more general, allowing clipping of any coordinate,
  before and after division by w
- compute the z coordinate only at the fragment stage instead of each
  time clipping creates / moves a vertex, in addition to the fragment
  stage
- added VectorCoords to choose at compile-time different coordinates
  based on a template argument
- added transpose struct to allow shuffling of vectors coordinates
- added math::utils::lerp which interpolate linearly a float
- added Vector{2,3,4}::map() which maps a vector from one range to
  another
- added template parameter to DerivedVertex (and therefore
  TriangleDerived) to allow choosing which dimension to use
---
 src/o3d/deriv_vertex.hpp | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

(limited to 'src/o3d/deriv_vertex.hpp')

diff --git a/src/o3d/deriv_vertex.hpp b/src/o3d/deriv_vertex.hpp
index 5e8dc22..48e5912 100644
--- a/src/o3d/deriv_vertex.hpp
+++ b/src/o3d/deriv_vertex.hpp
@@ -5,12 +5,27 @@
 
 namespace engine::o3d {
 
+template<engine::math::VectorTypeConcept VectorType>
 struct DerivedVertex {
+    VectorType vertex;
+    float b0, b1;
+
+    constexpr DerivedVertex() {}
+
+    constexpr DerivedVertex(const VectorType& vertex, float b0, float b1) : vertex { vertex }, b0 { b0 }, b1 { b1 } {}
+};
+
+template<>
+struct DerivedVertex<engine::math::Vector4> {
     engine::math::Vector4 vertex;
     float b0, b1;
 
-    constexpr DerivedVertex div_by_w() const & {
-        return {vertex.div_by_w(), b0, b1};
+    constexpr DerivedVertex() {}
+
+    constexpr DerivedVertex(const engine::math::Vector4& vertex, float b0, float b1) : vertex { vertex }, b0 { b0 }, b1 { b1 } {}
+
+    constexpr DerivedVertex<engine::math::Vector3> div_by_w() const & {
+        return { vertex.div_by_w(), b0, b1 };
     }
 };
 
-- 
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