fix: correct use of specular strength and shininess + opacity

src/shaders/simple.fs

@@ -17,7 +17,12 @@ uniform vec3 diffuseColor;
 uniform vec3 specularColor;
 
 uniform float ambientStrength;
+
 uniform float specularStrength;
+uniform float shininess;
+uniform bool useSpecular;
+
+uniform float opacity;
 
 uniform sampler2D diffuseTex;
 uniform bool useTexture;
@@ -33,18 +38,31 @@ void main()
     vec3 reflectDir = reflect(-lightDir, norm);
 
     // Phong components
-    float spec = pow(max(dot(viewDir, reflectDir), 0.0), 32);
-    vec3 specular = specularStrength * spec * specularColor; 
+    // float spec = pow(max(dot(viewDir, reflectDir), 0.0), clamp(shininess, 2, 256));
+    // vec3 specular = (useSpecular) ? specularStrength * spec * specularColor : vec3(0.0);
+
+    vec3 halfDir = normalize(lightDir + viewDir);
+    float spec = pow(max(dot(norm, halfDir), 0.0), clamp(shininess, 2.0, 256.0));
+    vec3 specular = (useSpecular) ? specularStrength * spec * specularColor : vec3(0.0);
 
     float diff = max(dot(norm, lightDir), 0.0);
     vec3 diffuse = diff * diffuseColor;
 
     vec3 ambient = ambientStrength * ambientColor;
 
+    float distance    = length(lightPos - vertexPos);
+    float attenuation = 1.0 / (1.0 + 0.09 * distance + 0.032 * (distance * distance));
+    // tweak 0.09 and 0.032 for range/falloff
+
+    // diffuse  *= attenuation;
+    // specular *= attenuation;
+    // ambient  *= attenuation; // optional, sometimes left constant
+
     vec3 texColor = (useTexture)
         ? texture(diffuseTex, TexCoords).rgb
         : diffuseColor;
 
     vec3 result = (ambient + diffuse + specular) * texColor;
-    FragColor = vec4(result, 1.0);
+
+    FragColor = vec4(result, opacity);
 }