From a403c07e8ae848a3052b4013b2254fed7e88af9f Mon Sep 17 00:00:00 2001
From: jacob <jacob@cagori.com>
Date: Fri, 18 Jul 2025 00:54:13 -0500
Subject: [PATCH] lighting testing

---
 res/sh/common.hlsl |  1 +
 res/sh/sh_common.h |  3 ++-
 res/sh/shade.hlsl  | 54 ++++++++++++++++++++++++++++++++++++++++------
 src/gp_dx12.c      |  2 ++
 4 files changed, 53 insertions(+), 7 deletions(-)

diff --git a/res/sh/common.hlsl b/res/sh/common.hlsl
index 992be30f..fa5b075c 100644
--- a/res/sh/common.hlsl
+++ b/res/sh/common.hlsl
@@ -1,5 +1,6 @@
 #include "sh/sh_common.h"
 
+#define TAU     6.28318530718
 #define PI      3.14159265359
 #define GOLDEN  1.61803398875
 
diff --git a/res/sh/sh_common.h b/res/sh/sh_common.h
index 879e9f90..5c002a8a 100644
--- a/res/sh/sh_common.h
+++ b/res/sh/sh_common.h
@@ -118,6 +118,7 @@ SH_ASSERT_32BIT(struct sh_flood_constants, 6);  /* Expected 32bit root constant
  * ========================== */
 
 SH_STRUCT(sh_shade_constants {
+    SH_DECL(float, time);
     SH_DECL(uint, albedo_tex_urid);
     SH_DECL(uint, emittance_tex_urid);
     SH_DECL(uint, emittance_flood_tex_urid);
@@ -125,7 +126,7 @@ SH_STRUCT(sh_shade_constants {
     SH_DECL(uint, tex_width);
     SH_DECL(uint, tex_height);
 });
-SH_ASSERT_32BIT(struct sh_shade_constants, 6);  /* Expected 32bit root constant size in shader */
+SH_ASSERT_32BIT(struct sh_shade_constants, 7);  /* Expected 32bit root constant size in shader */
 
 /* ========================== *
  * Shape shader structures
diff --git a/res/sh/shade.hlsl b/res/sh/shade.hlsl
index 6ea5c963..29b72092 100644
--- a/res/sh/shade.hlsl
+++ b/res/sh/shade.hlsl
@@ -5,7 +5,7 @@
  * ========================== */
 
 #define ROOTSIG \
-    "RootConstants(num32BitConstants = 6, b0), " \
+    "RootConstants(num32BitConstants = 7, b0), " \
     "DescriptorTable(SRV(t0, space = 0, numDescriptors = unbounded, flags = DESCRIPTORS_VOLATILE)), " \
     "DescriptorTable(SRV(t0, space = 1, numDescriptors = unbounded, flags = DESCRIPTORS_VOLATILE)), " \
     "DescriptorTable(UAV(u0, space = 2, numDescriptors = unbounded, flags = DESCRIPTORS_VOLATILE)), " \
@@ -33,6 +33,51 @@ struct cs_input {
     DECLS(uint3, SV_DispatchThreadID);
 };
 
+#define SAMPLES 4
+#define MARCHES 16
+
+INLINE float4 get_light_in_dir(uint2 pos, float2 dir)
+{
+    float4 result = 0;
+    uint2 at = pos;
+    for (uint i = 0; i < MARCHES; ++i) {
+        uint2 flood = g_emittance_flood_textures[g_constants.emittance_flood_tex_urid][at];
+        int2 dist_vec = (int2)at - (int2)flood;
+        float dist = length(dist_vec);
+        if (dist < 2) {
+            result = g_gbuff_textures[g_constants.emittance_tex_urid][flood];
+            break;
+        } else {
+            at += dir * dist;
+        }
+    }
+    return result;
+}
+
+float rand_float_from_float2(float2 pos) {
+    return frac(sin(dot(pos.xy, float2(12.9898,78.233))) * 43758.5453123);
+}
+
+INLINE float4 get_light_at_pos(uint2 pos)
+{
+    float4 result = 0;
+    for (int i = 0; i < SAMPLES; ++i) {
+        float angle = TAU * (((float)i + rand_float_from_float2(pos + (float)i + sin(g_constants.time))) / ((float)SAMPLES - 1));
+        float2 dir = float2(sin(angle), cos(angle));
+        float4 light_in_dir = get_light_in_dir(pos, dir);
+        result += light_in_dir;
+    }
+    result /= SAMPLES;
+
+    return result;
+
+
+    // float4 emittance = g_gbuff_textures[g_constants.emittance_tex_urid][pos];
+    // uint2 emittance_flood = g_emittance_flood_textures[g_constants.emittance_flood_tex_urid][pos];
+    // emittance_flood *= (emittance_flood.x < 0xFFFF && emittance_flood.y < 0xFFFF);
+    // return float4(float(emittance_flood.x) / float(g_constants.tex_width), float(emittance_flood.y) / float(g_constants.tex_height), 0, 1);
+}
+
 [numthreads(8, 8, 1)]
 SH_ENTRY(ROOTSIG) void cs(struct cs_input input)
 {
@@ -42,12 +87,9 @@ SH_ENTRY(ROOTSIG) void cs(struct cs_input input)
     }
     float4 old_color = g_gbuff_textures[g_constants.write_tex_urid][id];
     float4 albedo = g_gbuff_textures[g_constants.albedo_tex_urid][id];
-    float4 emittance = g_gbuff_textures[g_constants.emittance_tex_urid][id];
+    float4 lighting = get_light_at_pos(id);
 
-    uint2 emittance_flood = g_emittance_flood_textures[g_constants.emittance_flood_tex_urid][id];
-    emittance_flood *= (emittance_flood.x < 0xFFFF && emittance_flood.y < 0xFFFF);
-
-    float4 final_color = old_color + albedo + float4(float(emittance_flood.x) / float(g_constants.tex_width), float(emittance_flood.y) / float(g_constants.tex_height), 0, 1);
+    float4 final_color = old_color + albedo + lighting;
 
     g_write_textures[g_constants.write_tex_urid][id] = final_color;
 }
diff --git a/src/gp_dx12.c b/src/gp_dx12.c
index 9c50946f..b311d249 100644
--- a/src/gp_dx12.c
+++ b/src/gp_dx12.c
@@ -2931,6 +2931,8 @@ void gp_run(struct gp_run_params params)
 
                 /* Set constants */
                 struct sh_shade_constants constants = ZI;
+                /* TODO: Remove this */
+                constants.time = sh_float_from_f32((f32)SECONDS_FROM_NS(sys_time_ns()));
                 constants.albedo_tex_urid = sh_uint_from_u32(sig->albedo->srv_descriptor->index);
                 constants.emittance_tex_urid = sh_uint_from_u32(sig->emittance->srv_descriptor->index);
                 constants.emittance_flood_tex_urid = sh_uint_from_u32(emittance_flood_read->srv_descriptor->index);