feat: Make inverse square falloff a toggleable feature

src/game/game.cpp

@@ -798,7 +798,7 @@ bool Game::handleKeyDown(const SDL_KeyboardEvent &event) {
 
         case SDLK_F3:
             if (_options.developer) {
-                setFeatureEnabled(Feature::SelfIllumAsLights, !isFeatureEnabled(Feature::SelfIllumAsLights));
+                setFeatureEnabled(Feature::InverseSquareFalloff, !isFeatureEnabled(Feature::InverseSquareFalloff));
             }
             return true;
 

src/render/featureutil.cpp

@@ -28,8 +28,9 @@ namespace render {
 static unordered_map<Feature, bool> g_features {
     { Feature::PBR, false },
     { Feature::HDR, false },
-    { Feature::SelfIllumAsLights, false },
-    { Feature::DynamicRoomLighting, false }
+    { Feature::InverseSquareFalloff, false },
+    { Feature::DynamicRoomLighting, false },
+    { Feature::SelfIllumAsLights, false }
 };
 
 bool isFeatureEnabled(Feature feature) {

src/render/featureutil.h

@@ -24,8 +24,9 @@ namespace render {
 enum class Feature {
     PBR,
     HDR,
-    SelfIllumAsLights,
-    DynamicRoomLighting
+    InverseSquareFalloff,
+    DynamicRoomLighting,
+    SelfIllumAsLights
 };
 
 bool isFeatureEnabled(Feature feature);

src/render/shaders.cpp

@@ -64,6 +64,7 @@ const int FEATURE_SHADOWS = 0x200;
 const int FEATURE_BILLBOARD = 0x400;
 const int FEATURE_WATER = 0x800;
 const int FEATURE_HDR = 0x1000;
+const int FEATURE_INVSQRFALLOFF = 0x2000;
 
 struct Light {
     vec4 position;
@@ -693,11 +694,17 @@ void main() {
 
             vec3 radiance = uLights[i].color.rgb;
             if (uLights[i].position.w == 1.0) {
-                float D = length(uLights[i].position.xyz - fragPosition);
-                D *= D;
-                float R = uLights[i].radius;
-                R *= R;
-                float attenuation = uLights[i].multiplier * (R / (R + D));
+                float attenuation;
+                if (isFeatureEnabled(FEATURE_INVSQRFALLOFF)) {
+                    float distance = length(uLights[i].position.xyz - fragPosition);
+                    attenuation = 1.0 / (distance * distance);
+                } else {
+                    float D = length(uLights[i].position.xyz - fragPosition);
+                    D *= D;
+                    float R = uLights[i].radius;
+                    R *= R;
+                    attenuation = uLights[i].multiplier * (R / (R + D));
+                }
                 radiance *= attenuation;
             }
 

src/render/shaders.h

@@ -77,6 +77,7 @@ struct UniformFeatureFlags {
     static constexpr int billboard = 0x400;
     static constexpr int water = 0x800;
     static constexpr int hdr = 0x1000;
+    static constexpr int invSqrFalloff = 0x2000;
 };
 
 struct GeneralUniforms {

src/scene/node/modelnodescenenode.cpp

@@ -237,6 +237,10 @@ void ModelNodeSceneNode::renderSingle(bool shadowPass) {
                 shaderLight.multiplier = lights[i]->multiplier();
                 shaderLight.radius = lights[i]->radius();
             }
+
+            if (isFeatureEnabled(Feature::InverseSquareFalloff)) {
+                uniforms.general.featureMask |= UniformFeatureFlags::invSqrFalloff;
+            }
         }
 
         if (diffuseTexture) {