add attenuation

GLMakie/assets/shader/lighting.frag

@@ -53,12 +53,10 @@ vec3 calc_point_light(int idx, vec3 normal, vec3 color) {
     vec3 light_dir = normalize(light_vec);
 
     // How weak has the light gotten due to distance
-    float attentuation = 1.0;
-    // float attentuation = 1.0 / (
-    //     light_parameters[idx].x +
-    //     light_parameters[idx].y * dist +
-    //     light_parameters[idx].z * dist * dist
-    // );
+    // float attentuation = 1.0 / (1.0 + dist * dist * dist);
+    float attentuation = 1.0 / (
+        1.0 + light_parameters[idx].x * dist + light_parameters[idx].y * dist * dist
+    );
 
     return attentuation * blinn_phong(light_colors[idx], normal, light_dir, color);
 }

src/lighting.jl

@@ -61,11 +61,26 @@ A point-like light source placed at the given `position` with the given light
 struct PointLight <: AbstractLight
     color::Observable{RGBf}
     position::Observable{Vec3f}
+    attenuation::Observable{Vec2f}
 end
 
+# no attenuation
+PointLight(color, position) = PointLight(color, position, Vec2f(0))
+# automatic attenuation
+PointLight(color, position, range::Real) = PointLight(color, position, default_attenuation(range))
+
 light_type(::PointLight) = LightType.PointLight
 light_color(l::PointLight) = l.color[]
 light_position(l::PointLight) = l.position[]
+light_parameters(l::PointLight) = to_ndim(Vec3f, l.attenuation[], 0)
+
+# fit of values used on learnopengl/ogre3d
+function default_attenuation(range::Real)
+    return Vec2f(
+        4.690507869767646 * range ^ -1.009712247799057,
+        82.4447791934059 * range ^ -2.0192061630628966
+    )
+end
 
 
 """