From 9964260e0da150eb646e4e5f12edd42dad117b11 Mon Sep 17 00:00:00 2001
From: tali <iitalics@gmail.com>
Date: Mon, 22 Jan 2024 12:58:48 -0500
Subject: [PATCH] refactor matrix muls when computing transform

---
 src/adam/adam.ml | 15 +++++++--------
 src/n2/n2.ml     | 22 +++++++++++-----------
 2 files changed, 18 insertions(+), 19 deletions(-)

diff --git a/src/adam/adam.ml b/src/adam/adam.ml
index da5820d..cdb32b5 100644
--- a/src/adam/adam.ml
+++ b/src/adam/adam.ml
@@ -109,15 +109,14 @@ module Mat2A = struct
       dst.a5 <- src.a5;
     end
 
-  let[@inline] mul (lhs : t) (rhs : t) : unit =
-    let { a0; a1; a2; a3; a4; a5 } = lhs in
+  let[@inline] multiply (dst : t) (lhs : t) (rhs : t) : unit =
     begin
-      lhs.a0 <- (a0 * rhs.a0) + (a1 * rhs.a3);
-      lhs.a1 <- (a0 * rhs.a1) + (a1 * rhs.a4);
-      lhs.a2 <- (a0 * rhs.a2) + (a1 * rhs.a5) + a2;
-      lhs.a3 <- (a3 * rhs.a0) + (a4 * rhs.a3);
-      lhs.a4 <- (a3 * rhs.a1) + (a4 * rhs.a4);
-      lhs.a5 <- (a3 * rhs.a2) + (a4 * rhs.a5) + a5;
+      dst.a0 <- (lhs.a0 * rhs.a0) + (lhs.a1 * rhs.a3);
+      dst.a1 <- (lhs.a0 * rhs.a1) + (lhs.a1 * rhs.a4);
+      dst.a2 <- (lhs.a0 * rhs.a2) + (lhs.a1 * rhs.a5) + lhs.a2;
+      dst.a3 <- (lhs.a3 * rhs.a0) + (lhs.a4 * rhs.a3);
+      dst.a4 <- (lhs.a3 * rhs.a1) + (lhs.a4 * rhs.a4);
+      dst.a5 <- (lhs.a3 * rhs.a2) + (lhs.a4 * rhs.a5) + lhs.a5;
     end
 
   (*
diff --git a/src/n2/n2.ml b/src/n2/n2.ml
index eb8f9db..fe620f8 100644
--- a/src/n2/n2.ml
+++ b/src/n2/n2.ml
@@ -15,7 +15,7 @@ module Transform_graph = struct
     | Null
     | Node of {
         idx : int;
-        parent : node;
+        parent_tf : mat2a option;
         model_tf : mat2a;
         world_tf : mat2a;
       }
@@ -37,11 +37,15 @@ module Transform_graph = struct
 
   let add t parent =
     let model_tf = mat2a 0.0 0.0 1.0 1.0 in
-    let world_tf = mat2a 0.0 0.0 1.0 1.0 in
+    let parent_tf, world_tf =
+      match parent with
+      | Null -> None, model_tf
+      | Node p -> Some p.world_tf, mat2a 0.0 0.0 1.0 1.0
+    in
     let node =
       Node {
         idx = t.size;
-        parent;
+        parent_tf;
         model_tf;
         world_tf;
       }
@@ -53,14 +57,10 @@ module Transform_graph = struct
     let buf = t.buffer in
     for i = 0 to t.size - 1 do
       match buf.(i) with
-      | Null -> ()
-      | Node n ->
-        match n.parent with
-        | Null ->
-          Mat2A.copy n.world_tf ~src:n.model_tf
-        | Node p ->
-          Mat2A.copy n.world_tf ~src:p.world_tf;
-          Mat2A.mul n.world_tf n.model_tf;
+      | Node { model_tf; world_tf; parent_tf = Some parent_tf; _ } ->
+        Mat2A.multiply world_tf parent_tf model_tf
+      | _ ->
+        ()
     done
 
   let world = function