graphics: phong: Use Blinn-Phong method for specular highlights.

1 files changed, 2 insertions, 1 deletions

diff --git a/data/shaders/phong-frag.glsl b/data/shaders/phong-frag.glsl
index 9d8e40c..7cab3f8 100644
--- a/data/shaders/phong-frag.glsl
+++ b/data/shaders/phong-frag.glsl
@@ -174,7 +174,8 @@ void main() {
     float diffuseFactor = posDot(lightDir, normal);
     vec3 reflectDir = reflect(-lightDir, normal);
     vec3 diffuseColor = baseDiffuseColor * diffuseFactor;
-    float specularFactor = pow(posDot(viewDir, reflectDir), material.shininess);
+    vec3 halfVector = normalize(lightDir + viewDir);
+    float specularFactor = pow(posDot(halfVector, normal), material.shininess);
     vec3 specularColor = baseSpecularColor * specularFactor;
     color += (diffuseColor + specularColor) * radiance;
   }