From e07ea55a6ab7c886aa5800c1934e85b93c2a3b46 Mon Sep 17 00:00:00 2001
From: btipling <bjorn@ambientchill.com>
Date: Sat, 17 Aug 2024 13:05:40 -0700
Subject: [PATCH] Add ability to set camera heading

Set it for plane distance scene so that it looks at the side the plane
is pointing
---
 src/foundations/physics/camera.zig            | 27 +++++++++++++++++--
 src/foundations/scenes/look_at/LookAt.zig     |  1 +
 .../scenes/plane_distance/PlaneDistance.zig   |  4 +--
 .../scenes/plane_distance/PlaneDistanceUI.zig |  2 +-
 4 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/src/foundations/physics/camera.zig b/src/foundations/physics/camera.zig
index 3c74ae4..91f7bc0 100644
--- a/src/foundations/physics/camera.zig
+++ b/src/foundations/physics/camera.zig
@@ -15,7 +15,7 @@ pub fn Camera(comptime T: type, comptime IntegratorT: type) type {
         camera_orientation: math.rotation.Quat = .{ 1, 0, 0, 0 },
         cursor_pos: math.vector.vec3 = .{ 0, 0, 0 },
         cursor_mode: bool = false,
-        use_camera: bool = false,
+        use_camera: bool = true,
         fly_mode: bool = false,
         persp_m: math.matrix,
         mvp: math.matrix,
@@ -35,7 +35,14 @@ pub fn Camera(comptime T: type, comptime IntegratorT: type) type {
         const world_right: math.vector.vec3 = .{ 0, 0, 1 };
         const world_forward: math.vector.vec3 = .{ 0, 1, 0 };
 
-        pub fn init(allocator: std.mem.Allocator, cfg: *config, scene: T, integrator: IntegratorT, pos: math.vector.vec3) *Self {
+        pub fn init(
+            allocator: std.mem.Allocator,
+            cfg: *config,
+            scene: T,
+            integrator: IntegratorT,
+            pos: math.vector.vec3,
+            heading: ?f32,
+        ) *Self {
             const cam = allocator.create(Self) catch @panic("OOM");
             const s = @as(f32, @floatFromInt(cfg.width)) / @as(f32, @floatFromInt(cfg.height));
             const mvp = math.matrix.transformMatrix(
@@ -43,6 +50,19 @@ pub fn Camera(comptime T: type, comptime IntegratorT: type) type {
                 math.matrix.leftHandedXUpToNDC(),
             );
 
+            var camera_heading: math.rotation.Quat = .{ 1, 0, 0, 0 };
+            if (heading) |h| {
+                std.debug.print("setting heading\n", .{});
+                const a: math.rotation.AxisAngle = .{
+                    .angle = h,
+                    .axis = world_up,
+                };
+                var q = math.rotation.axisAngleToQuat(a);
+                q = math.vector.normalize(q);
+                q = math.rotation.multiplyQuaternions(camera_heading, q);
+                camera_heading = math.vector.normalize(q);
+            }
+
             cam.* = .{
                 .allocator = allocator,
                 .camera_pos = pos,
@@ -52,6 +72,8 @@ pub fn Camera(comptime T: type, comptime IntegratorT: type) type {
                 .movement = undefined,
                 .scene = scene,
                 .integrator = integrator,
+                .camera_orientation = camera_heading,
+                .camera_orientation_heading = camera_heading,
             };
             cam.movement = physics.movement.init(cam.camera_pos, 0, .none);
             cam.updateCameraMatrix();
@@ -371,6 +393,7 @@ pub fn Camera(comptime T: type, comptime IntegratorT: type) type {
                 .{ .program = p, .uniform = uniform },
             ) catch @panic("OOM");
             rhi.setUniformMatrix(p, uniform, self.mvp);
+            self.updateMVP();
         }
     };
 }
diff --git a/src/foundations/scenes/look_at/LookAt.zig b/src/foundations/scenes/look_at/LookAt.zig
index 4445436..d49a28f 100644
--- a/src/foundations/scenes/look_at/LookAt.zig
+++ b/src/foundations/scenes/look_at/LookAt.zig
@@ -29,6 +29,7 @@ pub fn init(allocator: std.mem.Allocator, cfg: *config) *LookAt {
         lkt,
         integrator,
         .{ 1, 3.5, 1 },
+        null,
     );
     errdefer cam.deinit(allocator);
     const grid = scenery.Grid.init(allocator);
diff --git a/src/foundations/scenes/plane_distance/PlaneDistance.zig b/src/foundations/scenes/plane_distance/PlaneDistance.zig
index e7734f4..bdd1194 100644
--- a/src/foundations/scenes/plane_distance/PlaneDistance.zig
+++ b/src/foundations/scenes/plane_distance/PlaneDistance.zig
@@ -30,7 +30,8 @@ pub fn init(allocator: std.mem.Allocator, cfg: *config) *PlaneDistance {
         cfg,
         pd,
         integrator,
-        .{ 0, 0, 0 },
+        .{ 0, 200, -100 },
+        std.math.pi * 0.75,
     );
     errdefer cam.deinit(allocator);
     const grid = scenery.Grid.init(allocator);
@@ -88,7 +89,6 @@ pub fn updatePlane(self: *PlaneDistance, m: math.matrix) void {
     const n = math.vector.normalize(math.vector.crossProduct(u, v));
     const d: f32 = math.vector.dotProduct(math.vector.negate(n), q);
     self.plane = math.geometry.Plane.init(n, d);
-    self.plane.debug();
 }
 
 pub fn updatePlaneTransform(self: *PlaneDistance, prog: u32) void {
diff --git a/src/foundations/scenes/plane_distance/PlaneDistanceUI.zig b/src/foundations/scenes/plane_distance/PlaneDistanceUI.zig
index 39c5241..86d8de5 100644
--- a/src/foundations/scenes/plane_distance/PlaneDistanceUI.zig
+++ b/src/foundations/scenes/plane_distance/PlaneDistanceUI.zig
@@ -4,7 +4,7 @@ rotation: [3]f32 = .{
     std.math.pi,
     std.math.pi,
 },
-translate: [3]f32 = .{ -100, 100, -100 },
+translate: [3]f32 = .{ -100, -100, -100 },
 updated: bool = true,
 
 const PlaneDistanceUI = @This();