From be36b310b469e07a137d4783cb14038371546e7b Mon Sep 17 00:00:00 2001
From: Paul Mathieu <paul@ponteilla.net>
Date: Fri, 14 Feb 2025 19:05:49 +0100
Subject: [PATCH] skycraft: can walk around the earth

---
 skycraft/draw.ts  |  4 +++-
 skycraft/index.ts | 40 ++++++++++++++++++++++++++++++++--------
 2 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/skycraft/draw.ts b/skycraft/draw.ts
index 24e531b..5d611d7 100644
--- a/skycraft/draw.ts
+++ b/skycraft/draw.ts
@@ -312,10 +312,12 @@ export function draw(context) {
 
     gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
 
+    const thirdPerson = context.landed ? se3.identity() : se3.translation(0, 1, 4);
+
     const playerView = [
         player.tf,  // player position & orientation
         camera.tf,  // camera orientation relative to player
-        se3.translation(0, 1, 4),  // step back from the player
+        thirdPerson,
     ];
     if (context.landed) {
         const body = context.landedBody;
diff --git a/skycraft/index.ts b/skycraft/index.ts
index 6d61b75..afd4bd9 100644
--- a/skycraft/index.ts
+++ b/skycraft/index.ts
@@ -173,10 +173,20 @@ function initUiListeners(canvas: HTMLCanvasElement, context) {
             }
         };
         const moveListener = e => {
-//            context.camera.orientation[0] -= e.movementY / 500;
-//            context.camera.orientation[1] -= e.movementX / 500;
-            context.camera.tf =[
-                context.camera.tf,
+            const cam = context.camera;
+            if (context.landed) {
+                cam.orientation[1] -= e.movementX / 500;
+                cam.orientation[0] -= e.movementY / 500;
+                cam.tf = [
+                    se3.roty(cam.orientation[1]),
+                    se3.rotx(cam.orientation[0]),
+                ].reduce(se3.product);
+
+                return;
+            }
+
+            cam.tf =[
+                cam.tf,
                 se3.roty(-e.movementX / 500),
                 se3.rotx(-e.movementY / 500),
             ].reduce(se3.product);
@@ -252,21 +262,25 @@ function moveOnGround(context, forward, right) {
         se3.orientationOnly(context.player.tf),
         context.camera.tf,
     );
-    const dir = [right, 0, -forward, 0];
+    const dir = se3.apply(tf, [right, 0, -forward, 0]);
     if (context.flying) {
         context.player.tf = [
-            context.player.tf,
             se3.translation(...dir),
+            context.player.tf,
         ].reduce(se3.product);
         return;
     }
 
-    const dv = linalg.scale(se3.apply(tf, dir), 10);
+    const dv = linalg.scale(dir, 10);
+
     const maxSpeed = 8;
     const airMovement = 0.08;
 
     if (context.isOnGround) {
-        context.player.velocity = dv;
+        const up = upDirection(context);
+        const vertical = linalg.dot(dv, up);
+        const horizontal = linalg.diff(dv, linalg.scale(up, vertical));
+        context.player.velocity = horizontal;
         return;
     }
 
@@ -466,6 +480,11 @@ function effectiveGravity(position: number[], rootBody: Body) : number[] {
     return acceleration;
 }
 
+function upDirection(context) {
+    const gravity = landedGravity(context);
+    return linalg.normalize(linalg.scale(gravity, -1));
+}
+
 function landedGravity(context) {
     // just clamp "down" to one of our six directions
     const pos = context.player.position;
@@ -558,6 +577,11 @@ function updateLandedPhysics(context, dt) {
     }
     context.isOnGround = isOnGround;
     context.player.tf = se3.setPosition(context.player.tf, newPos);
+
+    // up is up
+    const p = context.player;
+    const currentOrientation = slerp(p.tf, alignUp(p.tf, upDirection(context)), 0.1);
+    p.tf = se3.setOrientation(p.tf, currentOrientation);
 }
 
 function updatePhysics(time: number, context) {