Fixed immediate mode lighting, improved-ish modern gl lighting

shaders/fragment/default.glsl

@@ -1,26 +1,96 @@
 # version 330 core
+const int MAX_LIGHTS = 4;
+
+struct Light {
+  float end;
+  float type;
+  vec3 position;
+
+  vec3 diffuse;
+  vec3 ambient;
+  vec3 specular;
+
+  vec3 direction;
+
+  float intensity;
+};
+
 
 in vec3 outPosition;
 in vec3 outColor;
 in vec4 outNormal;
 in vec3 outUV;
 in float outTextureID;
-in vec3 outLightPos;
+in Light outLights[MAX_LIGHTS];
+in float outTotalLights;
 in vec3 outFragPos;
+in vec3 outCameraPos;
+in vec3 outInverseNormal;
 
 // optimizing compilers are annoying at this stage of my understanding of GLSL
 vec4 lokiVar;
 
+// https://learnopengl.com/Lighting/Multiple-lights
+vec3 calculatePointLight(Light light) {
+  vec3 viewDir = normalize(outCameraPos - outFragPos);
+  vec3 lightDir = normalize(light.position - outFragPos);
+  float diff = max(dot(vec3(outNormal), lightDir), 0.0);
+  vec3 reflectDir = reflect(-lightDir, vec3(outNormal));
+  float spec = pow(max(dot(viewDir, reflectDir), 0.0), 16.0);
+
+  float distance    = length(light.position - outFragPos);
+  float attenuation = 1.0 / (1.0 + 0.09 * distance +
+                      0.032 * (distance * distance));
+
+  vec3 ambient  = light.ambient  * outColor;
+  vec3 diffuse  = light.diffuse  * outColor;
+  vec3 specular = light.specular * spec * vec3(1.0, 1.0, 1.0);
+
+  ambient  *= attenuation;
+  diffuse  *= attenuation;
+  specular *= attenuation;
+
+  return (ambient + diffuse + specular);
+}
+
+// https://learnopengl.com/Lighting/Basic-Lighting
+vec3 calculateBasicLight(Light light) {
+  vec3 lightDir = normalize(light.position - outFragPos);
+
+  float ambientStrength = 0.25;
+  vec3 ambient = ambientStrength * light.ambient;
+
+  float diff = max(dot(normalize(vec3(outNormal)), lightDir), 0.0);
+  vec3 diffuse = diff * light.diffuse;
+
+  float specularStrength = 0.5;
+  vec3 viewDir = normalize(outCameraPos - outFragPos);
+  vec3 reflectDir = reflect(-lightDir, outInverseNormal);
+  float spec = pow(max(dot(viewDir, reflectDir), 0.0), 32);
+  vec3 specular = specularStrength * spec * light.specular;
+
+  return vec3(ambient + diffuse + specular);
+}
+
+vec3 calculateLighting() {
+  vec3 result = vec3(0.0, 0.0, 0.0);
+
+  for (int i = 0; i < min(int(outTotalLights), MAX_LIGHTS); i++) {
+    if (int(outLights[i].type) == 0) {
+      result += calculateBasicLight(outLights[i]);
+    } else if (int(outLights[i].type) == 1) {
+      result += calculateBasicLight(outLights[i]);
+    }
+  }
+
+  return result;
+}
+
 void main() {
   lokiVar = vec4(outColor, 1.0) + outNormal + vec4(outUV, 1.0) + vec4(outTextureID, 1.0, 1.0, 1.0);
   lokiVar = normalize(lokiVar);
 
-  vec3 lightDir = normalize(outLightPos - outFragPos);
-  vec3 ambient = vec3(0.5, 0.5, 0.35);
-  float diffuse = max(dot(vec3(outNormal), lightDir), -0.2);
-  vec3 specular = vec3(0, 0, 0);
-
-  vec3 result =(ambient + diffuse + specular) * outColor;
+  vec3 result = calculateLighting() * outColor;
 
   gl_FragColor = vec4(result, 1.0);
 }