package net.minecraftforge.client.model.obj;

import net.minecraft.client.renderer.Tessellator;
import net.minecraft.util.Vec3;
import cpw.mods.fml.relauncher.Side;
import cpw.mods.fml.relauncher.SideOnly;

@SideOnly(Side.CLIENT)
public class Face {

    public Vertex[] vertices;
    public Vertex[] vertexNormals;
    public Vertex faceNormal;
    public TextureCoordinate[] textureCoordinates;
    public int glDrawingMode;

    public Vertex calculateFaceNormal() {

        Vec3 v1 = Vec3.createVectorHelper(vertices[1].x - vertices[0].x, vertices[1].y - vertices[0].y, vertices[1].z - vertices[0].z);
        Vec3 v2 = Vec3.createVectorHelper(vertices[2].x - vertices[0].x, vertices[2].y - vertices[0].y, vertices[2].z - vertices[0].z);
        Vec3 normalVector = null;
        
        normalVector = v1.crossProduct(v2).normalize();
        
        return new Vertex((float)normalVector.xCoord, (float)normalVector.yCoord, (float)normalVector.zCoord);
    }

    public void render(Tessellator tessellator, float scale) {

        this.render(tessellator, 0F, scale);
    }

    public void render(Tessellator tessellator, float textureOffset, float scale) {

        tessellator.startDrawing(glDrawingMode);
        
        if (faceNormal == null) {
            faceNormal = this.calculateFaceNormal();
        }
        
        tessellator.setNormal(faceNormal.x, faceNormal.y, faceNormal.z);

        float averageU = 0F;
        float averageV = 0F;

        if (textureCoordinates.length != 0) {
            for (int i = 0; i < textureCoordinates.length; ++i) {
                averageU += textureCoordinates[i].u;
                averageV += textureCoordinates[i].v;
            }
    
            averageU = averageU / textureCoordinates.length;
            averageV = averageV / textureCoordinates.length;
        }

        float offsetU, offsetV;

        for (int i = 0; i < vertices.length; ++i) {

            if (textureCoordinates.length != 0) {
                offsetU = textureOffset;
                offsetV = textureOffset;
    
                if (textureCoordinates[i].u > averageU) {
                    offsetU = -offsetU;
                }
                if (textureCoordinates[i].v > averageV) {
                    offsetV = -offsetV;
                }
    
                tessellator.addVertexWithUV(vertices[i].x * scale, vertices[i].y * scale, vertices[i].z * scale, textureCoordinates[i].u + offsetU, textureCoordinates[i].v + offsetV);
            }
            else {
                tessellator.addVertex(vertices[i].x * scale, vertices[i].y * scale, vertices[i].z * scale);
            }
        }

        tessellator.draw();
    }
    
    public void render(Tessellator tessellator, int glDrawingMode, float scale) {

        this.render(tessellator, glDrawingMode, 0F, scale);
    }
    
    public void render(Tessellator tessellator, int glDrawingMode, float textureOffset, float scale) {

        tessellator.startDrawing(glDrawingMode);
        
        if (faceNormal == null) {
            faceNormal = this.calculateFaceNormal();
        }
        
        tessellator.setNormal(faceNormal.x, faceNormal.y, faceNormal.z);

        float averageU = 0F;
        float averageV = 0F;

        if (textureCoordinates.length != 0) {
            for (int i = 0; i < textureCoordinates.length; ++i) {
                averageU += textureCoordinates[i].u;
                averageV += textureCoordinates[i].v;
            }
    
            averageU = averageU / textureCoordinates.length;
            averageV = averageV / textureCoordinates.length;
        }

        float offsetU, offsetV;

        for (int i = 0; i < vertices.length; ++i) {

            if (textureCoordinates.length != 0) {
                offsetU = textureOffset;
                offsetV = textureOffset;
    
                if (textureCoordinates[i].u > averageU) {
                    offsetU = -offsetU;
                }
                if (textureCoordinates[i].v > averageV) {
                    offsetV = -offsetV;
                }
    
                tessellator.addVertexWithUV(vertices[i].x * scale, vertices[i].y * scale, vertices[i].z * scale, textureCoordinates[i].u + offsetU, textureCoordinates[i].v + offsetV);
            }
            else {
                tessellator.addVertex(vertices[i].x * scale, vertices[i].y * scale, vertices[i].z * scale);
            }
        }

        tessellator.draw();
    }
}