add: added lighting classes and a shader to use multiple lights

resources/shaders/light_shader.glsl

@@ -0,0 +1,153 @@
+#version 330 core
+out vec4 FragColor;
+
+in vec3 Normal;
+in vec2 TexCoords;
+in vec3 FragPos;
+
+struct DirLight {
+    vec3 direction;
+    vec3 color;
+
+    vec3 ambient;
+    vec3 diffuse;
+    vec3 specular;
+};
+
+struct PointLight {
+    vec3 position;  
+  
+    vec3 ambient;
+    vec3 diffuse;
+    vec3 specular;
+    vec3 color;
+	
+    float constant;
+    float linear;
+    float quadratic;
+};
+
+struct SpotLight {
+    vec3 position; 
+    vec3 direction; 
+  
+    vec3 ambient;
+    vec3 diffuse;
+    vec3 specular;
+    vec3 color;
+	
+    float constant;
+    float linear;
+    float quadratic;
+    float cutOff;
+    float outerCutOff;
+};
+
+uniform sampler2D texture_diffuse1;
+uniform vec3 viewPos;
+uniform DirLight dirLight;
+#define NR_POINT_LIGHTS 16
+uniform PointLight pointLights[NR_POINT_LIGHTS];
+uniform int pointLightCount;
+uniform SpotLight spotLight;
+
+vec3 CalcDirLight(DirLight light, vec3 normal, vec3 viewDir)
+{
+    // ambient
+    float ambientStrength = 0.1;
+    vec3 ambient = ambientStrength * light.color;
+	
+	// diffuse 
+	vec3 norm = normalize(Normal);
+	vec3 lightDir = normalize(-light.direction);
+	float diff = max(dot(norm, lightDir), 0.0);
+	vec3 diffuse  = diff * light.color;
+	
+	// specular
+    float specularStrength = 0.5;
+	vec3 reflectDir = reflect(-lightDir, norm);  
+	float spec = pow(max(dot(viewDir, reflectDir), 0.0), 32);
+	vec3 specular = specularStrength * spec * light.color;
+		
+	return (ambient + diffuse + specular);
+}
+
+vec3 CalcPointLight(PointLight light, vec3 normal, vec3 fragPos, vec3 viewDir)
+{
+    float distance    = length(light.position - FragPos);
+	float attenuation = 1.0 / (light.constant + light.linear * distance + light.quadratic * (distance * distance));
+
+	// ambient// ambient
+    float ambientStrength = 0.1;
+    vec3 ambient = ambientStrength * light.color;
+	
+	// diffuse 
+	vec3 norm = normalize(Normal);
+	vec3 lightDir = normalize(light.position - FragPos);
+	float diff = max(dot(norm, lightDir), 0.0);
+	vec3 diffuse  = diff * light.color;
+	
+	// specular
+    float specularStrength = 0.5;
+	vec3 reflectDir = reflect(-lightDir, norm);  
+	float spec = pow(max(dot(viewDir, reflectDir), 0.0), 32);
+	vec3 specular = specularStrength * spec * light.color;
+
+	ambient  *= attenuation; 
+	diffuse  *= attenuation;
+	specular *= attenuation;
+		
+	return (ambient + diffuse + specular);
+}
+
+vec3 CalcSpotLight(SpotLight light, vec3 normal, vec3 fragPos, vec3 viewDir)
+{
+    // Calculate the direction of the light
+    vec3 lightDir = normalize(light.position - FragPos);
+
+    // Calculate the angle between the light direction and the spotlight direction
+    float theta = dot(lightDir, normalize(-light.direction));
+    float epsilon   = light.cutOff - light.outerCutOff;
+    float intensity = clamp((theta - light.outerCutOff) / epsilon, 0.0, 1.0);
+    float distance    = length(light.position - FragPos);
+    float attenuation = 1.0 / (light.constant + light.linear * distance + light.quadratic * (distance * distance));
+
+    // ambient
+    float ambientStrength = 0.1;
+    vec3 ambient = ambientStrength * light.color;
+    
+    // diffuse 
+    vec3 norm = normalize(Normal);
+    float diff = max(dot(norm, lightDir), 0.0);
+    vec3 diffuse  = diff * light.color;
+    
+    // specular
+    float specularStrength = 0.5;
+    vec3 reflectDir = reflect(-lightDir, norm);  
+    float spec = pow(max(dot(viewDir, reflectDir), 0.0), 32);
+    vec3 specular = specularStrength * spec * light.color;
+
+    // Apply attenuation and intensity
+    ambient  *= attenuation; 
+    diffuse  *= attenuation * intensity;
+    specular *= attenuation * intensity;
+        
+    return (ambient + diffuse + specular);
+}
+
+void main()
+{
+    // properties
+    vec3 norm = normalize(Normal);
+    vec3 viewDir = normalize(viewPos - FragPos);
+
+    // phase 1: Directional lighting
+    vec3 result = CalcDirLight(dirLight, norm, viewDir);
+    // phase 2: Point lights
+    for(int i = 0; i < pointLightCount; i++)
+        result += CalcPointLight(pointLights[i], norm, FragPos, viewDir);    
+    // phase 3: Spot light
+    result += CalcSpotLight(spotLight, norm, FragPos, viewDir);    
+    
+    FragColor = texture(texture_diffuse1, TexCoords) * vec4(result, 1.0);
+}