Vertex and Fragment shaders

lighting.vsh

// VERTEX SHADER


//
//  Lighting.vsh

const int MaxLights = 3;

struct Light {
    highp vec3 position;
    lowp vec4 diffuse;
    lowp vec4 ambient;
    lowp vec4 specular;
    lowp vec3 attenuation;
};

struct LightArray {
    lowp int activeLights;
    Light allLights[MaxLights];
};

struct Material {
    lowp vec4 diffuse;
    lowp vec4 specular;
    lowp vec4 ambient;
    lowp float shininess;
    lowp float hasTexture;
};


attribute vec3 normalAttr;
attribute vec3 position;
attribute vec2 texture0;

varying lowp vec2 textureVarying0;
varying mediump vec3 normal;
varying mediump vec3 eyeDirection;
varying mediump vec3 lightDirections[MaxLights];
varying mediump float attenuation[MaxLights];
varying mediump vec3 halfVectors[MaxLights];

uniform LightArray lights;
uniform Material material0;
uniform lowp vec4 sceneAmbient;
uniform highp mat4 matProjection;
uniform highp mat4 matModelView;
uniform highp mat4 matModel;
uniform highp mat4 matModelViewProjection;
uniform highp mat4 matNormal;


void main()
{
    normal = vec3(matNormal * vec4(normalAttr, 1.0));

    highp vec4 worldPosition = matModel * vec4(position, 1.0);
    eyeDirection = vec3( (matModelView * vec4(position, 1.0)).xyz);
    
    lowp int i;
    mediump float dist;
    for (i = 0; i < lights.activeLights; i++) {
        lightDirections[i] = (lights.allLights[i].position.xyz - worldPosition.xyz); 
        dist = length(lightDirections[i]);
        halfVectors[i] = normalize(lights.allLights[i].position + lightDirections[i]);
        attenuation[i] = 1.0 / ( lights.allLights[i].attenuation.x + lights.allLights[i].attenuation.y * dist + lights.allLights[i].attenuation.z * dist * dist);
    }
    gl_Position = matModelViewProjection * vec4(position, 1.0);

    textureVarying0 = texture0;
}


// FRAGMENT SHADER



uniform lowp vec4 sceneAmbient;
uniform LightArray lights;
uniform Material material0;
uniform sampler2D tex0;

void main()
{
    
    highp vec4 final_color = sceneAmbient; 
    highp vec4 frontDiffuse;
    if(material0.hasTexture > 1.0){
        frontDiffuse = texture2D(tex0, textureVarying0);
    } else {
        frontDiffuse = material0.diffuse;
    }
    mediump vec3 N = normalize(normal);
    lowp int i;
    mediump vec3 halfV;
    mediump float ndothv;
    mediump vec3 E = normalize(eyeDirection);
    for (i=0; i<lights.activeLights; ++i)
    {
        mediump vec3 L = normalize(lightDirections[i]);
        mediump float lambertTerm = dot(N,L);
        if (lambertTerm > 0.0)
        {
            final_color += (lights.allLights[i].ambient * material0.ambient) * attenuation[i];
            final_color += lights.allLights[i].diffuse * frontDiffuse * lambertTerm * attenuation[i];
            halfV = normalize(halfVectors[i]);
            ndothv = max(dot(N, halfV), 0.0);
            final_color += attenuation[i] * material0.specular * lights.allLights[i].specular * pow(ndothv, material0.shininess);
        }
    }
    gl_FragColor = final_color;
}