pushMatrix() NullPointerException

Processing Coding Questions
1

Hello everyone, I am writing a game using processing in Eclipse, but I get a strange NullPointerException error when using pushMatrix in two of my classes. Even taking out the pushMatrix() and popMatrix() doesn’t work, causing the program to throw the error at translate(). I cannot figure out what the error is. What is causing the error to occur?
Here is the code:

import processing.core.*;
public class Face extends PApplet {
  float x1;
  float x2;
  float y1; 
  float y2;
  float z1; 
  float z2;
  float size;
  boolean isFront, isBack, isRight, isLeft, isTop, isBottom;
  int col;
  PVector position;
  boolean wireframe;
  boolean switchTexture;
  public Face (float s) {
    x1 = -s/2; 
    x2 = s/2;
    y1 = -s/2; 
    y2 = s/2;
    z1 = -s/2; 
    z2 = s/2;
    size = s;
    isFront = false;
    isRight = false;
    isBack = false;
    isLeft = false;
    isTop = false;
    isBottom = false;
    wireframe = false;
    switchTexture = false;
  }
  public void display() {
    pushMatrix();
    translate(position.x, position.y, position.z);
    beginShape();
    if (!wireframe) {
      noStroke();
    } else {
      stroke(0);
      noFill();
      noTexture();
    }
    texture(Game.grass3);
    if (isFront) {
      vertex(x1, y1, z1, 0, 0);
      vertex(x2, y1, z1, size/2, 0);
      vertex(x2, y2, z1, size/2, size/2);
      vertex(x1, y2, z1, 0, size/2);
    }
    if (isRight) {
      vertex(x2, y1, z1, 0, 0);
      vertex(x2, y1, z2, size/2, 0);
      vertex(x2, y2, z2, size/2, size/2);
      vertex(x2, y2, z1, 0, size/2);
    }
    if (isBack) {
      vertex(x2, y1, z2, 0, 0);
      vertex(x1, y1, z2, size/2, 0);
      vertex(x1, y2, z2, size/2, size/2);
      vertex(x2, y2, z2, 0, size/2);
    }
    if (isLeft) {
      vertex(x1, y1, z2, 0, 0);
      vertex(x1, y1, z1, size/2, 0);
      vertex(x1, y2, z1, size/2, size/2);
      vertex(x1, y2, z2, 0, size/2);
    }
    if (isTop) {
      texture(Game.grass2);
      vertex(x1, y1, z2, 0, 0);
      vertex(x2, y1, z2, size/2, 0);
      vertex(x2, y1, z1, size/2, size/2);
      vertex(x1, y1, z1, 0, size/2);
    }
    if (isBottom) {
      vertex(x1, y2, z1, 0, 0);
      vertex(x2, y2, z1, size/2, 0);
      vertex(x2, y2, z2, size/2, size/2);
      vertex(x1, y2, z2, 0, size/2);
    }
    endShape();
    popMatrix();
  }
}

Note: the game class, “Game” is the class in which I make the PApplet.

2

Hello,

This may give you some insight:

:)

3

Looks like you have forgotten to define it.

4

You should pass PAppplet’s object to the constructor of your class, not extend it in your class

5

Thank you all, so I finished defining the position variable, and I should put a PApplet in the constructor to handle all the drawing functions?

6

Hello,

Please read the link I already provided.

You declared it and it is now “null”.

Look at your other variables and the constructor.

You really do not need me for this one.

I don’t want to rob you of the joy of discovery and fixing your own code.

:)

References: