package de.gamezock.metacraft.ui;

import javax.media.opengl.GL;
import javax.media.opengl.GL2;
import javax.vecmath.Point3f;
import javax.vecmath.Vector3f;

import de.gamezock.metacraft.data.Map;
import de.gamezock.metacraft.data.Tile;

public class Renderer {
  private Main main;
  
  public Renderer(Main main) {
    this.main = main;
  }
  
  private void renderTileQuad(GL2 gl, Tile tile, int x, int y) {
    float[][] heightmap = tile.getData().getHeightmap();
    
    float[] h = new float[4];
    h[0] = heightmap[x][y];
    h[1] = heightmap[x+1][y];
    h[2] = heightmap[x+1][y+1];
    h[3] = heightmap[x][y+1];
    
    float center = (h[0] + h[1] + h[2] + h[3]) / 4;
    
    for(int i = 0; i < 4; ++i) {
      int i_1 = (i+1)%4;
      int i_2 = (i+2)%4;
      
      Point3f v1 = new Point3f(x + i_1/2, y + i/2, h[i]);
      Point3f v2 = new Point3f(x+0.5f, y+0.5f, center);
      Point3f v3 = new Point3f(x + i_2/2, y + i_1/2, h[i_1]);
      
      Vector3f edge1 = new Vector3f(), edge2 = new Vector3f();
      
      edge1.sub(v1, v2);
      edge2.sub(v3, v2);
      
      Vector3f normal = new Vector3f();
      normal.cross(edge1, edge2);
      normal.normalize();
      
      gl.glColor3f(1, 1, 1);
      gl.glNormal3f(normal.x, normal.y, normal.z);
      gl.glVertex3f(v1.x, v1.y, v1.z);
      gl.glVertex3f(v2.x, v2.y, v2.z);
      gl.glVertex3f(v3.x, v3.y, v3.z);
    }
  }
  
  private void renderTile(GL2 gl, Tile tile) {
    gl.glBegin(GL.GL_TRIANGLES);
    
    for(int i = 0; i < tile.getData().getSize(); ++i) {
      for(int j = 0; j < tile.getData().getSize(); ++j) {
        renderTileQuad(gl, tile, i, j);
      }
    }
    
    gl.glEnd();
  }
  
  public void render(GL2 gl) {
    gl.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT);
    
    Map currentMap = main.getCurrentMap();
    
    gl.glPushMatrix();
    gl.glRotatef((System.currentTimeMillis()%3600)/10.0f, 0, 0, 1);
    
    for(int i = 0; i < currentMap.getWidth(); ++i) {
      for(int j = 0; j < currentMap.getHeight(); ++j) {
        gl.glPushMatrix();
        gl.glTranslatef(i*currentMap.getTileSize(), j*currentMap.getTileSize(), currentMap.getTileHeight(i, j));
        
        renderTile(gl, currentMap.getTile(i, j));
        
        gl.glPopMatrix();
      }
    }
    
    gl.glPopMatrix();
  }

}