float w = width / 2.f;
float h = height / 2.f;

// Right vertices with outwards normals
                      X   Y  NorX NorY
vertices.emplace_back(w, -h, 1.f, 0.f);
vertices.emplace_back(w,  h, 1.f, 0.f);

// Bottom vertices with outwards normals
vertices.emplace_back( w, h, 0.f, 1.f);
vertices.emplace_back(-w, h, 0.f, 1.f);

// Left vertices with outwards normals
vertices.emplace_back(-w,  h, -1.f, 0.f);
vertices.emplace_back(-w, -h, -1.f, 0.f);

// Top vertices with outwards normals
vertices.emplace_back(-w, -h, 0.f, -1.f);
vertices.emplace_back( w, -h, 0.f, -1.f);

// Right vertices with inwards normals
vertices.emplace_back(w, -h, -1.f, 0.f);
vertices.emplace_back(w,  h, -1.f, 0.f);

// ** SNIP **
// Here's the rest of "inverted normal" vertices
// ** SNIP

// Indices that make the triangles
// Right
indices.emplace_back(0);
indices.emplace_back(1);
indices.emplace_back(8);
indices.emplace_back(8);
indices.emplace_back(1);
indices.emplace_back(9);

// Down
indices.emplace_back(2);
indices.emplace_back(3);
indices.emplace_back(10);
indices.emplace_back(10);
indices.emplace_back(3);
indices.emplace_back(11);

// ** SNIP ** And here's the rest of the indices ** SNIP **

// Vertex attributes
layout(location = 0) in vec3 in_position;
layout(location = 3) in vec3 in_normal; // Y is always 0

// Uniforms
uniform mat4 u_world;
uniform mat4 u_view;
uniform mat4 u_projection;
uniform vec2 u_lightPosition;

void main() {
    // Get the world position of the vertex
    vec4 vPos = u_world * vec4(in_position, 1.0);

    // Flatten to XZ-plane
    vec2 xzPos = vec2(vPos.x, vPos.z);

    // Get the direction from the vertex to the light
    vec2 dir = normalize(xzPos - u_lightPosition);

    // If the normals point outwards, extrude them
    if(dot(dir, vec2(in_nor.x, in_nor.z)) < 0) {
        vPos.x += dir.x * 10000;
        vPos.z += dir.y * 10000;
    }

    // Apply the position
    gl_Position = u_projection * u_view * vPos;
}