From 3634e53cc68671a576754d6bb668f585f7e2c53d Mon Sep 17 00:00:00 2001
From: quou <quou@disroot.org>
Date: Sat, 22 Feb 2025 23:24:35 +1100
Subject: basic temporal coherence for shadow

---
 c2.cpp               |  1 +
 intermediate/ts.glsl | 15 +++++++++++++--
 lighting.cpp         |  8 ++++----
 renderer.cpp         |  6 +++---
 renderer.hpp         |  2 ++
 5 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/c2.cpp b/c2.cpp
index 3867280..3a14ea5 100644
--- a/c2.cpp
+++ b/c2.cpp
@@ -836,6 +836,7 @@ struct C2 : public App {
 
 		Texture& bb = dev->get_texture(hdr_target);
 		pcam.asp = (float)bb.w / (float)bb.h;
+		renderer.prev_vp = pcam.get_proj() * pcam.get_view();
 		orbit_cam.update_orbit(*this);
 		pcam.update();
 		lighting.update(dev, ctx, *world, renderer, scene);
diff --git a/intermediate/ts.glsl b/intermediate/ts.glsl
index 23195f6..61dd728 100644
--- a/intermediate/ts.glsl
+++ b/intermediate/ts.glsl
@@ -138,11 +138,22 @@ vec3 get_world_pos(float depth, vec2 uv) {
 }
 
 void main() {
+	float w_prev = 0.9;
+	float w_cur = 0.1;
 	vec2 uv = interpolator.uv;
 	float d = texture(depthmap, uv).r;
 	vec3 wpos = get_world_pos(d, uv);
-	float prev = texture(previous, uv).r;
+	vec4 prev_pos = config.prev_vp * vec4(wpos, 1.0);
+	vec2 prev_uv = (prev_pos.xy / prev_pos.w) * 0.5 + 0.5;
+	float prev = texture(previous, prev_uv).r;
 	float current = get_shadow(caster_config.index, wpos);
-	shadow_amount = (prev + current) * 0.5;
+	if (
+		prev_uv.x < 0.0 || prev_uv.x > 1.0 || 
+		prev_uv.y < 0.0 || prev_uv.y > 1.0
+	) {
+		w_prev = 0.0;
+		w_cur = 1.0;
+	}
+	shadow_amount = (prev * w_prev + current * w_cur);
 }
 #endif
diff --git a/lighting.cpp b/lighting.cpp
index 4f1fdfb..1eb4298 100644
--- a/lighting.cpp
+++ b/lighting.cpp
@@ -108,7 +108,7 @@ void Lighting::recreate(Device* dev, int w, int h) {
 	for (i = 0; i < 2; i++) {
 		ss_shadows[i] = dev->create_texture(
 			"Shadow accumulation buffer",
-			texture_format_r8i,
+			texture_format_r16f,
 			Texture_Flags::sampleable | Texture_Flags::colour_target,
 			w,
 			h,
@@ -121,10 +121,10 @@ void Lighting::recreate(Device* dev, int w, int h) {
 			ss_shadow_slices[i][j] = dev->alias_texture(
 				ss_shadows[i],
 				"Shadow accumulation buffer slice",
-				texture_format_r8i,
+				texture_format_r16f,
 				Texture_Flags::colour_target,
-				shadow_res,
-				shadow_res,
+				w,
+				h,
 				1,
 				1,
 				1,
diff --git a/renderer.cpp b/renderer.cpp
index ffc0a3c..a9d590a 100644
--- a/renderer.cpp
+++ b/renderer.cpp
@@ -54,9 +54,8 @@ void Renderer::make_ts_sampler(Device* d) {
 	s.min = Filter_Mode::point;
 	s.mag = Filter_Mode::point;
 	s.mip = Filter_Mode::point;
-	s.address_u = Address_Mode::border;
-	s.address_v = Address_Mode::border;
-	s.border[0] = 0.0f;
+	s.address_u = Address_Mode::clamp;
+	s.address_v = Address_Mode::clamp;
 	ts_sampler = d->create_sampler("temporal shadow sampler", s);
 }
 
@@ -185,6 +184,7 @@ void Renderer::temporal_shadows(
 	}
 	cbuf->inv_view = cam.get_view().inverse();
 	cbuf->inv_proj = cam.get_proj().inverse();
+	cbuf->prev_vp = prev_vp;
 	ts_config.unmap(dev);
 	ts_config2.unmap(dev);
 	ctx.debug_push("temporal shadows");
diff --git a/renderer.hpp b/renderer.hpp
index 46f5331..387032d 100644
--- a/renderer.hpp
+++ b/renderer.hpp
@@ -67,6 +67,8 @@ struct Renderer {
 	Sampler_Id ts_sampler;
 	Staged_Buffer ts_config, ts_config2;
 
+	m4f prev_vp;
+
 	Sampler_Id clamped_linear;
 	Texture_Id env_cubemap;
 
-- 
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