From 96b5ac2200457ad7f2edef466ff58b6fcc02b4ff Mon Sep 17 00:00:00 2001
From: numzero <numzer0@yandex.ru>
Date: Mon, 30 Dec 2024 16:46:25 +0300
Subject: [PATCH] Split camera location and viewport

---
 src/bin/minitracer/main.rs    | 25 +++++++++++++++----------
 src/bin/minitracer/trace.rs   | 20 +++++++++++++-------
 src/bin/minitracer/trace.wgsl |  8 ++++++--
 3 files changed, 34 insertions(+), 19 deletions(-)

diff --git a/src/bin/minitracer/main.rs b/src/bin/minitracer/main.rs
index 83c9c87..f6780a3 100644
--- a/src/bin/minitracer/main.rs
+++ b/src/bin/minitracer/main.rs
@@ -1,6 +1,6 @@
 use std::error::Error;
 
-use glam::{mat3, uvec2, Vec3};
+use glam::{mat3, uvec2, vec3, Vec3};
 use image::ImageReader;
 use present::Presenter;
 use trace::{Tracer, TracerData, TracerEnv};
@@ -22,18 +22,21 @@ struct CamLoc {
 	right: Vec3,
 }
 
-fn make_viewport(cam: CamLoc, w: u32, h: u32) -> trace::CameraLocation {
+fn make_viewport(w: u32, h: u32) -> trace::Viewport {
 	let size = uvec2(w, h).as_vec2();
 	let size = size.normalize();
-	let (w, h, d) = (size.x, size.y, 1.);
-
-	let fwd = d * cam.forward.normalize();
-	let up = h * cam.right.cross(fwd).normalize();
-	let right = w * up.cross(fwd).normalize();
+	trace::Viewport {
+		corner: vec3(size.x, size.y, 1.),
+	}
+}
 
+fn convert_location(cam: CamLoc) -> trace::CameraLocation {
+	let fwd = cam.forward.normalize();
+	let up = cam.right.cross(fwd).normalize();
+	let right = up.cross(fwd).normalize();
 	trace::CameraLocation {
 		eye: cam.eye,
-		view: mat3(fwd, right, up),
+		view: mat3(right, up, fwd),
 	}
 }
 
@@ -143,7 +146,8 @@ fn main() {
 							let eye = camera_params.to_sphere(time).center;
 							let right = camera_params.deriv(time);
 							let forward = target_params.to_sphere(time).center - eye;
-							let view = make_viewport(CamLoc { eye, forward, right }, size.width, size.height);
+							let viewport = make_viewport(size.width, size.height);
+							let location = convert_location(CamLoc { eye, forward, right });
 							let spheres: Vec<_> = sphere_params.iter().map(|p| p.to_sphere(time)).collect();
 							let data = TracerData::new(&device, &tracer, &spheres);
 							tracer.render(
@@ -156,7 +160,8 @@ fn main() {
 									sphere_count: N_SPHERES,
 									seed: frame,
 								},
-								view,
+								viewport,
+								location,
 							);
 						}
 					}
diff --git a/src/bin/minitracer/trace.rs b/src/bin/minitracer/trace.rs
index 9eef951..f19deab 100644
--- a/src/bin/minitracer/trace.rs
+++ b/src/bin/minitracer/trace.rs
@@ -13,6 +13,11 @@ pub struct Params {
 	pub seed: u32,
 }
 
+#[derive(Debug, Clone, Copy)]
+pub struct Viewport {
+	pub corner: Vec3,
+}
+
 #[derive(Debug, Clone, Copy)]
 pub struct CameraLocation {
 	pub eye: Vec3,
@@ -39,13 +44,13 @@ struct CameraData {
 	pad4: f32,
 }
 
-impl From<CameraLocation> for CameraData {
-	fn from(value: CameraLocation) -> Self {
+impl From<(Viewport, CameraLocation)> for CameraData {
+	fn from(value: (Viewport, CameraLocation)) -> Self {
 		CameraData {
-			u: value.view.x_axis,
-			v: value.view.y_axis,
-			w: value.view.z_axis,
-			eye: value.eye,
+			u: value.0.corner.x * value.1.view.x_axis,
+			v: value.0.corner.y * value.1.view.y_axis,
+			w: value.0.corner.z * value.1.view.z_axis,
+			eye: value.1.eye,
 			pad1: 0.,
 			pad2: 0.,
 			pad3: 0.,
@@ -222,6 +227,7 @@ impl Tracer {
 		data: &TracerData,
 		env: &TracerEnv,
 		params: Params,
+		viewport: Viewport,
 		camera: CameraLocation,
 	) {
 		pass.set_pipeline(&self.pipeline);
@@ -230,7 +236,7 @@ impl Tracer {
 			0,
 			bytes_of(&ParamsData {
 				params,
-				camera: camera.into(),
+				camera: (viewport, camera).into(),
 			}),
 		);
 		pass.set_vertex_buffer(0, self.view_buf.slice(..));
diff --git a/src/bin/minitracer/trace.wgsl b/src/bin/minitracer/trace.wgsl
index 9bc320f..bd22c1c 100644
--- a/src/bin/minitracer/trace.wgsl
+++ b/src/bin/minitracer/trace.wgsl
@@ -3,7 +3,10 @@ struct Params {
 	min_strength: f32,
 	sphere_count: i32,
 	seed: u32,
-	view: mat3x3f,
+
+	right: vec3f,
+	up: vec3f,
+	forward: vec3f,
 	eye: vec3f,
 }
 
@@ -31,7 +34,8 @@ var<push_constant> params: Params;
 
 @vertex
 fn on_vertex(in: Vertex) -> Varying {
-	return Varying(params.view * vec3(1.0, in.screen), vec4(in.screen, 0.0, 1.0));
+	let m = mat3x3(params.right, params.up, params.forward);
+	return Varying(m * vec3(in.screen, 1.0), vec4(in.screen, 0.0, 1.0));
 }
 
 @fragment