Made an attempt at creating a glow effect for mobjects.

manimlib/mobject/mobject.py

@@ -80,7 +80,7 @@ def __init__(
         self,
         color: ManimColor = DEFAULT_MOBJECT_COLOR,
         opacity: float = 1.0,
-        shading: Tuple[float, float, float] = (0.0, 0.0, 0.0),
+        shading: Tuple[float, float, float, float] = (0.0, 0.0, 0.0, 0.0),
         # For shaders
         texture_paths: dict[str, str] | None = None,
         # If true, the mobject will not get rotated according to camera position
@@ -1432,16 +1432,21 @@ def set_shading(
         reflectiveness: float | None = None,
         gloss: float | None = None,
         shadow: float | None = None,
+        # TODO: `glow` does nothing at the moment;
+        # still needs to be implemented in the shader code in
+        # manimlib/shaders/inserts/finalize_color.glsl
+        glow: float | None = None,
         recurse: bool = True
     ) -> Self:
         """
         Larger reflectiveness makes things brighter when facing the light
         Larger shadow makes faces opposite the light darker
         Makes parts bright where light gets reflected toward the camera
+        Glow should add a glowing outline around the silhouette of the mobject
         """
         for mob in self.get_family(recurse):
             shading = mob.uniforms["shading"]
-            for i, value in enumerate([reflectiveness, gloss, shadow]):
+            for i, value in enumerate([reflectiveness, gloss, shadow, glow]):
                 if value is not None:
                     shading[i] = value
             mob.set_uniform(shading=shading, recurse=False)

manimlib/shaders/inserts/finalize_color.glsl

@@ -1,6 +1,6 @@
 uniform vec3 light_position;
 uniform vec3 camera_position;
-uniform vec3 shading;
+uniform vec4 shading;
 
 vec3 float_to_color(float value, float min_val, float max_val, vec3[9] colormap_data){
     float alpha = clamp((value - min_val) / (max_val - min_val), 0.0, 1.0);
@@ -14,11 +14,14 @@ vec3 float_to_color(float value, float min_val, float max_val, vec3[9] colormap_
 
 
 vec4 add_light(vec4 color, vec3 point, vec3 unit_normal){
-    if(shading == vec3(0.0)) return color;
+    if(shading == vec4(0.0)) return color;
 
     float reflectiveness = shading.x;
     float gloss = shading.y;
     float shadow = shading.z;
+    // glow does noting at the moment;
+    // shader code needs to be implemented to create a glow around the mobject
+    float glow = shading.w;
 
     vec4 result = color;
     vec3 to_camera = normalize(camera_position - point);

manimlib/shaders/inserts/get_unit_normal.glsl

@@ -7,7 +7,7 @@ vec3 get_unit_normal(vec3 p0, vec3 p1, vec3 p2){
 
     if(cp_norm > tol) return cp / cp_norm;
 
-    // Otherwise, three pionts form a line, so find
+    // Otherwise, three points form a line, so find
     // a normal vector to that line in the plane shared
     // with the z-axis
     vec3 comb = v1 + v2;

manimlib/shaders/true_dot/frag.glsl

@@ -26,7 +26,7 @@ void main() {
         frag_color.a *= pow(1 - r, glow_factor);
     }
 
-    if(shading != vec3(0.0)){
+    if(shading != vec4(0.0)){
         vec3 point_3d = point + radius * sqrt(1 - r * r) * to_cam;
         vec3 normal = normalize(point_3d - center);
         frag_color = finalize_color(frag_color, point_3d, normal);