From b59d0b1a1019d45efe587f2e9e2a5c89501a2adb Mon Sep 17 00:00:00 2001
From: numzero <numzer0@yandex.ru>
Date: Sun, 29 Dec 2024 21:14:23 +0300
Subject: [PATCH] HDR rendering

---
 src/bin/minitracer/main.rs      | 19 ++++++++++---------
 src/bin/minitracer/present.wgsl |  6 +++++-
 src/bin/minitracer/trace.wgsl   |  2 +-
 3 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/src/bin/minitracer/main.rs b/src/bin/minitracer/main.rs
index b99d12a..d9c8acc 100644
--- a/src/bin/minitracer/main.rs
+++ b/src/bin/minitracer/main.rs
@@ -50,8 +50,9 @@ fn main() {
 	let envmap = load_envmap(&device, &queue);
 	queue.submit([]);
 
-	let format = wgpu::TextureFormat::Bgra8UnormSrgb;
-	let mut tracer = Tracer::new(&device, format);
+	let output_format = wgpu::TextureFormat::Bgra8UnormSrgb;
+	let hdr_format = wgpu::TextureFormat::Rgba16Float;
+	let mut tracer = Tracer::new(&device, hdr_format);
 	let sphere_params: Vec<_> = {
 		let mut rng = rand_pcg::Pcg32::new(42, 0);
 		let distr = anim::SphereParamsDistribution::default();
@@ -59,7 +60,7 @@ fn main() {
 	};
 	let tracer_env = TracerEnv::new(&device, &tracer, &envmap);
 
-	let presenter = Presenter::new(&device, format);
+	let presenter = Presenter::new(&device, output_format);
 
 	let mut frame = 0;
 	let mut time = 0.0;
@@ -75,7 +76,7 @@ fn main() {
 						&device,
 						&wgpu::SurfaceConfiguration {
 							usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::COPY_DST,
-							format,
+							format: output_format,
 							width: physical_size.width,
 							height: physical_size.height,
 							present_mode: wgpu::PresentMode::Fifo,
@@ -109,7 +110,7 @@ fn main() {
 					let output = surface.get_current_texture().unwrap();
 					let view = output.texture.create_view(&wgpu::TextureViewDescriptor::default());
 					let size = output.texture.size();
-					let buf = device.create_texture(&wgpu::TextureDescriptor {
+					let hdr = device.create_texture(&wgpu::TextureDescriptor {
 						label: None,
 						size: wgpu::Extent3d {
 							width: 2 * size.width,
@@ -119,17 +120,17 @@ fn main() {
 						mip_level_count: 1,
 						sample_count: 1,
 						dimension: wgpu::TextureDimension::D2,
-						format,
+						format: hdr_format,
 						usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::TEXTURE_BINDING,
 						view_formats: &[],
 					});
-					let buf = buf.create_view(&wgpu::TextureViewDescriptor::default());
+					let hdr = hdr.create_view(&wgpu::TextureViewDescriptor::default());
 					let mut encoder = device.create_command_encoder(&wgpu::CommandEncoderDescriptor { label: None });
 					{
 						let mut render_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
 							label: None,
 							color_attachments: &[Some(wgpu::RenderPassColorAttachment {
-								view: &buf,
+								view: &hdr,
 								resolve_target: None,
 								ops: wgpu::Operations {
 									load: wgpu::LoadOp::Clear(wgpu::Color::TRANSPARENT),
@@ -157,7 +158,7 @@ fn main() {
 							occlusion_query_set: None,
 							timestamp_writes: None,
 						});
-						presenter.render(&device, &mut render_pass, &buf);
+						presenter.render(&device, &mut render_pass, &hdr);
 					}
 					queue.submit(std::iter::once(encoder.finish()));
 					output.present();
diff --git a/src/bin/minitracer/present.wgsl b/src/bin/minitracer/present.wgsl
index e206941..5fc83e9 100644
--- a/src/bin/minitracer/present.wgsl
+++ b/src/bin/minitracer/present.wgsl
@@ -17,5 +17,9 @@ fn on_vertex(in: Vertex) -> Varying {
 
 @fragment
 fn on_fragment(in: Varying) -> @location(0) vec4f {
-	return textureSample(tex, smp, in.tex);
+	let hdr = textureSample(tex, smp, in.tex).xyz;
+	let luminosity = dot(hdr, vec3(0.2126, 0.7152, 0.0722));
+	let color = hdr / luminosity;
+	let luma = luminosity / (luminosity + 1.0);
+	return vec4(luma * color, 1.0);
 }
diff --git a/src/bin/minitracer/trace.wgsl b/src/bin/minitracer/trace.wgsl
index 3a5352e..e1cffc4 100644
--- a/src/bin/minitracer/trace.wgsl
+++ b/src/bin/minitracer/trace.wgsl
@@ -99,7 +99,7 @@ fn trace_fragment(in: Varying) -> vec4f {
 		}
 	}
 
-	return clamp(result, vec4(0.0), vec4(1.0));
+	return result;
 }
 
 fn hash(key : u32) -> u32 {