Hello,

My traffic light model has some dark faces and I can’t seem to understand why?

I am using OpenGL.

This is my fragment shader:

#version 330 core
out vec4 FragColor;

in vec2 texCoord;

uniform sampler2D texture;

in vec3 color;

in vec3 normal;

in vec3 fragPos;

uniform vec3 lightColor;
uniform vec3 lightPos;
uniform vec3 viewPos;

void main()
{
    float ambientStrength = 0.8;
    float specularStrength = 0.2;

    float constant = 1.0f;
    float linearr = 0.09;
    float quadratic = 0.032;

    float distance    = length(lightPos - fragPos);
    float attenuation = 1.0 / (constant + linearr * distance + 
                    quadratic * (distance * distance));  

    vec3 ambient = lightColor * ambientStrength;

    vec3 norm = normalize(normal);
    vec3 lightDir = normalize(lightPos - fragPos);  

    float diff = max(dot(norm, lightDir), 0.0);
    vec3 diffuse = diff * lightColor;

    vec3 viewDir = normalize(viewPos - fragPos);
    vec3 reflectDir = reflect(-lightDir, norm); 

    float spec = pow(max(dot(viewDir, reflectDir), 0.0), 32);
    vec3 specular = specularStrength * spec * lightColor;   

    diffuse *= attenuation;
    specular *= attenuation;

    vec3 result = (ambient + diffuse + specular) * color * texture(texture, texCoord).rgb;

    FragColor = vec4(result, 1.0);
}

I uploaded my traffic light mesh on GitHub here:
https://github.com/hazh10/traffic/blob/main/trafficlight2.obj

Can someone explain why this happens because this doesn’t happen to any of the other meshes?