Develop Reference

MonoGame/XNA rotating an image

This code is to draw the tower. Square locations are the top left of the square. TILE_SIZE is simply the dimensions of the square.
SpriteBatch.Draw(TowerImage, new Rectangle(square.X * TILE_SIZE, square.Y * TILE_SIZE, TILE_SIZE, TILE_SIZE), null, Color.White, myTower.Rotation,
new Vector2(TILE_SIZE - 35, TILE_SIZE - 35), SpriteEffects.None, (float)0.0);
This code is how I determine the rotation
public void FaceTarget(Vector2 center, Vector2 enemyCenter)
{
Vector2 direction = center - enemyCenter;
direction.Normalize();
this.Rotation = (float)Math.Atan2(-direction.X, direction.Y);
}
I did this based on:
http://www.riemers.net/eng/Tutorials/XNA/Csharp/Series2D/Rotation.php
http://www.riemers.net/eng/Tutorials/XNA/Csharp/Series2D/Direction_to_Angle.php
The rotation is being really weird, here is how it looks normally:
But when it rotates it goes like this:
Finally when it looks down, it goes complete off path, it's not rotating by its center, but the entire image is moving why is it doing that?
Only the first image is actually the tower in the correct position
It seems like it is rotating of the top left point and I don't know why. Can anyone help?

Apparently, your sprite is taking into consideration as the origin of rotation a Vector2.Zero (or Vector2(0,0)) point. That means the upper left point of the Texture2D file.
I see that you are setting the origin in the Draw method to TILE_SIZE - 35 which makes me wonder, is the tile a square of 70 pixels W/H?
What happens if you replace the substraction with new Vector2(TowerImage.Width / 2, TowerImage.Height / 2)?
I'll leave you an example from this site which explains easily how to rotate an image following the mouse position at all times:
Update method:
MouseState mouse = Mouse.GetState();
mousePosition = new Vector2(mouse.X, mouse.Y);
Vector2 direction = mousePosition - position;
direction.Normalize();
rotation = (float)Math.Atan2(
(double)direction.Y,
(double)direction.X);
Draw method:
spriteBatch.Begin();
spriteBatch.Draw(
rocket,
position,
null,
Color.White,
rotation,
new Vector2(
rocket.Width / 2,
rocket.Height / 2),
1.0f,
SpriteEffects.None,
1.0f);
spriteBatch.End();
Check that in the posted code the rotation angle is calculated slightly different than yours, but the important piece of code is the calculation of the origin point in the Draw method.

XNA Texture2D Billboarding appears as a white block

Very odd problem, when I try and draw my billboard sprite it always appears as a white block, changing the .draw color property still draws it as white, it also doesn't matter it I use a jpeg, or transparent png.
[EDIT]
So I'm now trying to use a Viewport instead of a basic effect to just get an x and y screen coordinate, I'll fix any scaling issue later, however now the image stays in the exact same spot (on the screen, it doesn't change position based on the camera) and doesn't get any bigger or smaller based on how far away it is
My new billboard rendering function:
public void Draw(Camera camera, GraphicsDevice device, SpriteBatch spriteBatch, Texture2D Texture)
{
Viewport viewport = new Viewport(new Rectangle(0, 0, 800, 480));
Vector3 viewSpaceTextPosition = viewport.Project(this.position, camera.Projection, camera.View, camera.World);
spriteBatch.Begin();
spriteBatch.Draw(Texture, new Vector2(viewSpaceTextPosition.X, viewSpaceTextPosition.Y), null, Color.White, 0, new Vector2(Texture.Bounds.Center.X, Texture.Bounds.Center.Y), this.Scale, SpriteEffects.None, viewSpaceTextPosition.Z);
spriteBatch.End();
device.RasterizerState = RasterizerState.CullCounterClockwise;
device.BlendState = BlendState.Opaque;
device.DepthStencilState = DepthStencilState.Default;
}
So is my use of Viewport wrong or do I just need to use it's information differently in spriteBatch.Draw()?

I think this should do the trick using viewport project... taking two projection points and calculating its distance you get a value affected by depth... so if it's deeper that value will be smaller.
public void Draw(Camera camera, GraphicsDevice device, SpriteBatch spriteBatch, Texture2D Texture)
{
Vector3 pos1= device.Viewport.Project(
this.position,
camera.Projection, camera.View, camera.World);
Vector3 pos2= device.Viewport.Project(
this.position+ Vactor3.UnitY*10,
camera.Projection, camera.View, camera.World);
Vector2 pos = new Vector2(pos1.X, pos1.Y);
Vector2 origin = new Vector2(Texture.Bounds.Center.X, Texture.Bounds.Center.Y);
float Scale = Vector3.Distance(pos1, pos2) * CustomRatio;
spriteBatch.Begin();
spriteBatch.Draw(Texture, pos, null, Color.White, 0,
origin, Scale, SpriteEffects.None, 0);
spriteBatch.End();
device.RasterizerState = RasterizerState.CullCounterClockwise;
device.BlendState = BlendState.Opaque;
device.DepthStencilState = DepthStencilState.Default;
}
In other hand... your previous code seems to be extracted from a source that drinks from this article made by the guy behind Xna that explain how to use basiceffect to draw billboards in 3D with spritebatch...
http://blogs.msdn.com/b/shawnhar/archive/2011/01/12/spritebatch-billboards-in-a-3d-world.aspx
I hope it helps you

Figured it out, you have to enable textures on the effect and then set effect.Texture to the Texture2D you want to use just before calling spriteBatch.Begin() in the draw function

Position of sprite

Vector2 drawPos = (-screenPosition);
drawPos.X *= (float)device.DisplayMode.Width;
drawPos.Y *= (float)device.DisplayMode.Height;
spriteBatch.Draw(
texture,
drawPos,
getRectangle(),
Color.White,
rotation,
getOrigin(),
1.0f / zoom,
SpriteEffects.None,
0);
I have a drawPos essentialy being 0..1 and multiply that with the display width and height. screenposition is obtained by dragging the screen. With other elements, primitives, the position is correct and is exactly being dragged along with the input. However when drawing a sprite the sprite is moving to quickly, faster than the input, giving a sort of parallax effect, not what I want.
I somehow get the feeling I am using the parameters wrong, and spriteBatch.Draw(..) does not need pixelcoordinates..
Width and height is obtained by texture loader.
public Vector2 getOrigin()
{
return new Vector2(width / 2, height / 2);
}
public Rectangle getRectangle()
{
return new Rectangle(
0,
0,
width,
height);
}
Also, I am developing for Windows Phone.

The getRectangle() method is basically useless, you are specifying a source rectangle which is the same size as the texture - use null instead (unless ofcourse you've just simplified your code for us).
How is screenPosition defined? I don't understand why you'd times it by -1. You are also using the screen that the window is on to get width/height with device.DisplayMode which is something you should avoid because this will only work when your window is the same size as the screen.
Try drawing the sprite to Vector2.Zero without an origin, and with the sourceRectangle set to null. Slowly add back in your other parameters and see where the error is occuring. Can't really say much else without more information!
spriteBatch.Draw(
texture,
Vector2.Zero,
null,
Color.White,
0,
Vector2.Zero,
1,
SpriteEffects.None,
1);
This is what I would use to make sure the sprite is actually displaying properly.

Rotate a Texture2D with the Draw method in XNA?

I have a problem with rotating. I know that I can rotate a Texture2D object with the draw method.
My goal is to rotate a texture by 180°. For example, if I make a picture of a human with the camera where the head is at the bottom, I want to be able to rotate it so that the head is at the top again.
Here is the code or the rotation:
spriteBatch.Draw(Texture, Position, null, Color.White, MathHelper.Pi, new Vector2(), 1.0f, SpriteEffects.None, 0f);
The rotation works fine, but I have another problem:
If I add the texture to position 0,0 after rotating it, it's not visible anymore.
How do I rotate or maybe reflect the object, so that the red point will be at the top-left corner again?

http://msdn.microsoft.com/en-us/library/ff433989.aspx
public void Draw (
Texture2D texture,
Vector2 position,
Nullable<Rectangle> sourceRectangle,
Color color,
float rotation,
Vector2 origin,
Vector2 scale,
SpriteEffects effects,
float layerDepth)
//Using:
var origin = new Vector2()
{
X = texture.Width / 2,
Y = texture.Height/ 2
};
spriteBatch.Draw(texture, Vector2.Zero, null, Color.White, MathHelper.Pi, origin, 1f, SpriteEffects.None, 0f)`

C# directx sprite origin

i have this problem when my Sprite rotation origin is fixed at top left corner of window (same with sprite.Draw and sprite.Draw2D)
Either way if i change rotation center it's still at top left. I need sprite to rotate around its Z axis.
Edit:
I have tried this:
hereMatrix pm = Matrix.Translation(_playerPos.X + 8, _playerPos.Y + 8, 0);
sprite.Transform = Matrix.RotationZ(_angle) * pm;
sprite.Draw(playerTexture, textureSize, new Vector3(8, 8, 0), new Vector3(_playerPos.X, _playerPos.Y, 0), Color.White);
But it does not seem to works well...

When you draw it, is it in the correct place?
I believe that the multiplication order is reversed, and that you shouldn't be transforming by the players position in the transform.
// shift centre to (0,0)
sprite.Transform = Matrix.Translation(-textureSize.Width / 2, -textureSize.Height / 2, 0);
// rotate about (0,0)
sprite.Transform *= Matrix.RotationZ(_angle);
sprite.Draw(playerTexture, textureSize, Vector3.Zero,
new Vector3(_playerPos.X, _playerPos.Y, 0), Color.White);
Edit
You could also use the Matrix.Transformation method to get the matrix in one step.

I've got the solution for you, it's a simple method that you can use everytime you want to draw a sprite.
With this method you will be able to rotate the sprite with your desired rotation center.
public void drawSprite(Sprite sprite, Texture texture, Point dimension, Point rotationCenter, float rotationAngle, Point position)
{
sprite.Begin(SpriteFlags.AlphaBlend);
//First draw the sprite in position 0,0 and set your desired rotationCenter (dimension.X and dimension.Y represent the pixel dimension of the texture)
sprite.Draw(texture, new Rectangle(0, 0, dimension.X, dimension.Y), new Vector3(rotationCenter.X, rotationCenter.Y, 0), new Vector3(0, 0, 0), Color.White);
//Then rotate the sprite and then translate it in your desired position
sprite.Transform = Matrix.RotationZ(rotationAngle) * Matrix.Translation(position.X, position.Y, 0);
sprite.End();
}