From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 12 Apr 2021 14:40:04 +0000 (+0300)
Subject: Adjust specular calculation in the Phong shader
X-Git-Url: http://git.tdb.fi/?a=commitdiff_plain;h=4c11957c4e26b2c369f0399c85bafcb6eb58edd4;p=libs%2Fgl.git

Adjust specular calculation in the Phong shader

Since the look vector points towards the surface, it makes more sense
to calculate the reflected vector towards the light.  The calculation
is symmetric so the result is the same.
---

diff --git a/shaderlib/phong.glsl b/shaderlib/phong.glsl
index 482f895b..570024ab 100644
--- a/shaderlib/phong.glsl
+++ b/shaderlib/phong.glsl
@@ -85,10 +85,8 @@ vec3 phong_one_light(vec3 light, vec3 normal, vec3 look, vec3 light_color, vec3
 	vec3 color = light_color*surface_diffuse*diffuse_intensity;
 	if(use_specular)
 	{
-		/* The light vector points towards the light, so reflected will point
-		towards the surface - but so does the look vector. */
-		vec3 reflected = reflect(light, normal);
-		float specular_intensity = pow(max(dot(reflected, look), 0.0), shininess);
+		vec3 reflected = reflect(look, normal);
+		float specular_intensity = pow(max(dot(reflected, light), 0.0), shininess);
 		color += light_color*surface_specular*specular_intensity;
 	}
 	return color;