Bounding Box Collision with 2D Camera XNA - matrix

Question

I'm pulling my hair out trying the figure this out. I have a simple button, that checks for the mouse to be over, and then changes the texture if it is. It works fine. However, when I add a camera into the mix, it breaks everything. I've tried transforming both the mouse and rectangle I use for bounding-box collision, and it won't work. Here's my code for the button:
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace x.Graphics.UI
{
public enum ButtonStates
{
Normal,
Hover,
Pressed
}
public delegate void ButtonPress();
public class Button
{
public Texture2D Texture
{
get
{
Texture2D result = null;
switch (ButtonState)
{
case ButtonStates.Normal:
result = NormalTexture;
break;
case ButtonStates.Hover:
result = HoverTexture;
break;
case ButtonStates.Pressed:
result = DownTexture;
break;
}
return result;
}
}
public Vector2 Position { get; set; }
public event ButtonPress ButtonPressed;
public ButtonStates ButtonState { get; set; }
public Rectangle CollisionRect { get; set; }
private Texture2D NormalTexture;
private Texture2D HoverTexture;
private Texture2D DownTexture;
private MouseState mouseState;
private MouseState previousMouseState;
public Button(Texture2D normalTexture, Texture2D hoverTexture, Texture2D downTexture,
Vector2 position)
{
NormalTexture = normalTexture;
HoverTexture = hoverTexture;
DownTexture = downTexture;
Position = position;
mouseState = Mouse.GetState();
previousMouseState = mouseState;
CollisionRect = new Rectangle((int)Position.X, (int)Position.Y,
Texture.Width,
Texture.Height);
}
public void Update (MouseState currentState)
{
mouseState = currentState;
if (CollisionRect.Contains(new Point(mouseState.X, mouseState.Y)))
{
if (mouseState.LeftButton == Microsoft.Xna.Framework.Input.ButtonState.Pressed)
{
ButtonState = ButtonStates.Pressed;
ButtonPressed();
}
else
ButtonState = ButtonStates.Hover;
}
else
ButtonState = ButtonStates.Normal;
}
public void Update(MouseState currentState, Camera camera)
{
Vector2 mouse = new Vector2(mouseState.X, mouseState.Y);
mouse = Vector2.Transform(mouse, camera.InverseTransform);
CollisionRect = CalculateTransformedBoundingBox(CollisionRect, c.InverseTransform);
Console.WriteLine("Rectangle[X: {0}, y: {1}], Mouse:[X: {2}, Y: {3}]", CollisionRect.X, CollisionRect.Y, mouse.X, mouse.Y);
if (CollisionRect.Contains(new Point((int)mouse.X, (int)mouse.Y)))
{
if (mouseState.LeftButton == Microsoft.Xna.Framework.Input.ButtonState.Pressed)
{
ButtonState = ButtonStates.Pressed;
ButtonPressed();
}
else
ButtonState = ButtonStates.Hover;
}
else
ButtonState = ButtonStates.Normal;
}
public void Draw(SpriteBatch spriteBatch)
{
spriteBatch.Draw(Texture, Position, null, Color.White, 0.0f,
Vector2.Zero, 1.0f, SpriteEffects.None, 1.0f);
}
private Rectangle CalculateTransformedBoundingBox(Rectangle local, Matrix toWorldSpace)
{
Vector2 leftTop = new Vector2(local.Left, local.Top);
Vector2 rightTop = new Vector2(local.Right, local.Top);
Vector2 leftBottom = new Vector2(local.Left, local.Bottom);
Vector2 rightBottom = new Vector2(local.Right, local.Bottom);
Vector2.Transform(ref leftTop, ref toWorldSpace,
out leftTop);
Vector2.Transform(ref rightTop, ref toWorldSpace,
out rightTop);
Vector2.Transform(ref leftBottom, ref toWorldSpace,
out leftBottom);
Vector2.Transform(ref rightBottom, ref toWorldSpace,
out rightBottom);
// Find the minimum and maximum extents of the
// rectangle in world space
Vector2 min = Vector2.Min(Vector2.Min(leftTop, rightTop),
Vector2.Min(leftBottom, rightBottom));
Vector2 max = Vector2.Max(Vector2.Max(leftTop, rightTop),
Vector2.Max(leftBottom, rightBottom));
// Return that as a rectangle
return new Rectangle((int)min.X, (int)min.Y,
(int)(max.X - min.X), (int)(max.Y - min.Y));
}
}
}
And my code for the camera:
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace x.Graphics
{
public class Camera
{
protected float _zoom;
protected Matrix _transform;
protected Matrix _inverseTransform;
protected Vector2 _pos;
protected float _rotation;
protected Viewport _viewport;
protected MouseState _mState;
protected KeyboardState _keyState;
protected Int32 _scroll;
public float Zoom
{
get { return _zoom; }
set { _zoom = value; }
}
public Matrix Transform
{
get { return _transform; }
set { _transform = value; }
}
public Matrix InverseTransform
{
get { return _inverseTransform; }
}
public Vector2 Pos
{
get { return _pos; }
set { _pos = value; }
}
public float Rotation
{
get { return _rotation; }
set { _rotation = value; }
}
public Camera(Viewport viewport)
{
_zoom = 1.0f;
_scroll = 1;
_rotation = 0.0f;
_pos = Vector2.Zero;
_viewport = viewport;
}
public void Update()
{
Input();
MathHelper.Clamp(_zoom, 0.01f, 10.0f);
_rotation = ClampAngle(_rotation);
_transform = Matrix.CreateRotationZ(_rotation) *
Matrix.CreateScale(new Vector3(_zoom, _zoom, 1)) *
Matrix.CreateTranslation(_pos.X, _pos.Y, 0);
_inverseTransform = Matrix.Invert(_transform);
}
protected virtual void Input()
{
_mState = Mouse.GetState();
_keyState = Keyboard.GetState();
//Check Move
if (_keyState.IsKeyDown(Keys.A))
{
_pos.X += 10f;
}
if (_keyState.IsKeyDown(Keys.D))
{
_pos.X -= 10f;
}
if (_keyState.IsKeyDown(Keys.W))
{
_pos.Y -= 10f;
}
if (_keyState.IsKeyDown(Keys.S))
{
_pos.Y += 10f;
}
}
protected float ClampAngle(float radians)
{
while (radians < -MathHelper.Pi)
{
radians += MathHelper.TwoPi;
}
while (radians > MathHelper.Pi)
{
radians -= MathHelper.TwoPi;
}
return radians;
}
}
}
I'm not 100% sure what's wrong, but the mouse position only changes when I press a button. I'm really confused, I've never worked with cameras before. Any help would be really appreciated. Thanks!
UPDATE:
It detects the mouse as being over the button before I try and move the camera. After that, the coorindates of the rectangle are continually incremented.

Answer 1

Don't transform bounding box... is easy to transform mouse coordinates ... ;)
Use the inverse transform of your camera matrix to transform mouse coords to the same space of your bounding box.