From 5b6afd747fe2705c45d33e0767046550deeb87dd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dominik=20Madar=C3=A1sz?= <zaklaus@outlook.com>
Date: Wed, 28 Aug 2024 17:02:13 +0200
Subject: [PATCH] add: cubemap_sh_blend

---
 bind/v4k.lua              |  1 +
 demos/09-envmap.c         |  2 +-
 engine/joint/v4k.h        | 28 ++++++++++++++++++++++++++++
 engine/split/v4k_render.c | 25 +++++++++++++++++++++++++
 engine/split/v4k_render.h |  3 +++
 engine/v4k.c              | 25 +++++++++++++++++++++++++
 engine/v4k.h              |  3 +++
 7 files changed, 86 insertions(+), 1 deletion(-)

diff --git a/bind/v4k.lua b/bind/v4k.lua
index ceaef18..d484d2a 100644
--- a/bind/v4k.lua
+++ b/bind/v4k.lua
@@ -1128,6 +1128,7 @@ typedef struct cubemap_t {
  void cubemap_sh_reset(cubemap_t *c);
  void cubemap_sh_shader(cubemap_t *c);
  void cubemap_sh_add_light(cubemap_t *c, vec3 light, vec3 dir, float strength);
+ void cubemap_sh_blend(vec3 pos, float max_dist, unsigned count, cubemap_t *probes);
  unsigned fbo( unsigned texture_color, unsigned texture_depth, int wr_flags );
  void fbo_bind(unsigned id);
  void fbo_unbind();
diff --git a/demos/09-envmap.c b/demos/09-envmap.c
index 817d80a..5f01bc7 100644
--- a/demos/09-envmap.c
+++ b/demos/09-envmap.c
@@ -103,7 +103,7 @@ int main(int argc, char** argv) {
             skybox_render(&sky, cam.proj, cam.view);
 
             shader_bind(mdl.program);
-            shader_vec3v("u_coefficients_sh", 9, env_probe.cubemap.sh);
+            cubemap_sh_blend(vec3(0,0,0), 10.0f, 1, &env_probe.cubemap);
             shader_int("u_textured", false);
 
             model_render(mdl, cam.proj, cam.view, mdl.pivot, 0);
diff --git a/engine/joint/v4k.h b/engine/joint/v4k.h
index 636f5d6..c857456 100644
--- a/engine/joint/v4k.h
+++ b/engine/joint/v4k.h
@@ -17231,6 +17231,9 @@ API void       cubemap_sh_reset(cubemap_t *c);
 API void       cubemap_sh_shader(cubemap_t *c);
 API void       cubemap_sh_add_light(cubemap_t *c, vec3 light, vec3 dir, float strength);
 
+// lighting probe blending
+API void       cubemap_sh_blend(vec3 pos, float max_dist, unsigned count, cubemap_t *probes);
+
 // -----------------------------------------------------------------------------
 // fbos
 
@@ -383891,6 +383894,31 @@ void cubemap_sh_add_light(cubemap_t *c, vec3 light, vec3 dir, float strength) {
     c->sh[3] = add3(c->sh[3], scale3(scaled_light, -0.488603f * norm_dir.x));
 }
 
+void cubemap_sh_blend(vec3 pos, float max_dist, unsigned count, cubemap_t *probes) {
+    float total_weight = 0.0f;
+    vec3 final_sh[9] = {0};
+
+    // Iterate through each probe
+    for (unsigned i = 0; i < count; i++) {
+        float distance = len3(sub3(pos, probes[i].pos));
+        float weight = 1.0f - (distance / max_dist);
+        weight = weight * weight;
+
+        for (int s = 0; s < 9; s++) {
+            final_sh[s] = add3(final_sh[s], scale3(probes[i].sh[s], weight));
+        }
+
+        total_weight += weight;
+    }
+
+    // Normalize the final SH coefficients
+    for (int s = 0; s < 9; s++) {
+        final_sh[s] = scale3(final_sh[s], 1.0f / total_weight);
+    }
+
+    // Apply SH coefficients to the shader
+    shader_vec3v("u_coefficients_sh", 9, final_sh);
+}
 
 // -----------------------------------------------------------------------------
 // skyboxes
diff --git a/engine/split/v4k_render.c b/engine/split/v4k_render.c
index 7702afa..fad1957 100644
--- a/engine/split/v4k_render.c
+++ b/engine/split/v4k_render.c
@@ -2207,6 +2207,31 @@ void cubemap_sh_add_light(cubemap_t *c, vec3 light, vec3 dir, float strength) {
     c->sh[3] = add3(c->sh[3], scale3(scaled_light, -0.488603f * norm_dir.x));
 }
 
+void cubemap_sh_blend(vec3 pos, float max_dist, unsigned count, cubemap_t *probes) {
+    float total_weight = 0.0f;
+    vec3 final_sh[9] = {0};
+
+    // Iterate through each probe
+    for (unsigned i = 0; i < count; i++) {
+        float distance = len3(sub3(pos, probes[i].pos));
+        float weight = 1.0f - (distance / max_dist);
+        weight = weight * weight;
+
+        for (int s = 0; s < 9; s++) {
+            final_sh[s] = add3(final_sh[s], scale3(probes[i].sh[s], weight));
+        }
+
+        total_weight += weight;
+    }
+
+    // Normalize the final SH coefficients
+    for (int s = 0; s < 9; s++) {
+        final_sh[s] = scale3(final_sh[s], 1.0f / total_weight);
+    }
+
+    // Apply SH coefficients to the shader
+    shader_vec3v("u_coefficients_sh", 9, final_sh);
+}
 
 // -----------------------------------------------------------------------------
 // skyboxes
diff --git a/engine/split/v4k_render.h b/engine/split/v4k_render.h
index a2b6760..602b815 100644
--- a/engine/split/v4k_render.h
+++ b/engine/split/v4k_render.h
@@ -263,6 +263,9 @@ API void       cubemap_sh_reset(cubemap_t *c);
 API void       cubemap_sh_shader(cubemap_t *c);
 API void       cubemap_sh_add_light(cubemap_t *c, vec3 light, vec3 dir, float strength);
 
+// lighting probe blending
+API void       cubemap_sh_blend(vec3 pos, float max_dist, unsigned count, cubemap_t *probes);
+
 // -----------------------------------------------------------------------------
 // fbos
 
diff --git a/engine/v4k.c b/engine/v4k.c
index 72b623c..9f2c3c4 100644
--- a/engine/v4k.c
+++ b/engine/v4k.c
@@ -19006,6 +19006,31 @@ void cubemap_sh_add_light(cubemap_t *c, vec3 light, vec3 dir, float strength) {
     c->sh[3] = add3(c->sh[3], scale3(scaled_light, -0.488603f * norm_dir.x));
 }
 
+void cubemap_sh_blend(vec3 pos, float max_dist, unsigned count, cubemap_t *probes) {
+    float total_weight = 0.0f;
+    vec3 final_sh[9] = {0};
+
+    // Iterate through each probe
+    for (unsigned i = 0; i < count; i++) {
+        float distance = len3(sub3(pos, probes[i].pos));
+        float weight = 1.0f - (distance / max_dist);
+        weight = weight * weight;
+
+        for (int s = 0; s < 9; s++) {
+            final_sh[s] = add3(final_sh[s], scale3(probes[i].sh[s], weight));
+        }
+
+        total_weight += weight;
+    }
+
+    // Normalize the final SH coefficients
+    for (int s = 0; s < 9; s++) {
+        final_sh[s] = scale3(final_sh[s], 1.0f / total_weight);
+    }
+
+    // Apply SH coefficients to the shader
+    shader_vec3v("u_coefficients_sh", 9, final_sh);
+}
 
 // -----------------------------------------------------------------------------
 // skyboxes
diff --git a/engine/v4k.h b/engine/v4k.h
index d662ca0..1a4ffae 100644
--- a/engine/v4k.h
+++ b/engine/v4k.h
@@ -3298,6 +3298,9 @@ API void       cubemap_sh_reset(cubemap_t *c);
 API void       cubemap_sh_shader(cubemap_t *c);
 API void       cubemap_sh_add_light(cubemap_t *c, vec3 light, vec3 dir, float strength);
 
+// lighting probe blending
+API void       cubemap_sh_blend(vec3 pos, float max_dist, unsigned count, cubemap_t *probes);
+
 // -----------------------------------------------------------------------------
 // fbos