OrderedSortType

Introduction

The OrderedSortType property controls how Sprites and IDrawableBatches are ordered when they are drawn. Z Buffered Sprites do not use this property when drawing. The following available options exist:

Usage

The following code sets the SpriteManager's OrderedSortType to sort by distance from camera:

SpriteManager.OrderedSortType = SortType.DistanceFromCamera;

Code Example

The following code creates 10 Sprites, rotates them on the X axis, and sizes them to be a little larger so they overlap. Setting the OrderedSortType to DistanceFromCamera results in the Sprites overlapping properly whether the Camera is above or below the Sprites.

 for (int i = 0; i < 10; i++)
 {
     Sprite sprite = SpriteManager.AddSprite("redball.bmp");
     sprite.Y = - 15 + 3 * i;
     sprite.ScaleX = sprite.ScaleY = 12f;
     sprite.RotationX = 1.57f;
 }

 SpriteManager.OrderedSortType = SortType.DistanceFromCamera;

ZSecondaryParentY Details

The ZSecondaryParentY sort type is useful for top down and 3/4 view games. It allows moving objects (such as character entities) to be sorted based on their Y.

This is recommended for top-down and 3/4 view games. Note that Sprites use this sorting type only if they have the same Z. Therefore, if your entities have mulitple sprites with different Z values, they will interlace with other instances of the same entity.

For example if a character has a BodySprite and ShadowSprite, the ShadowSprite may have a Z value of -0.1 so that it always sorts behind the BodySprite of all other instances of the same entity type.

The following code shows how to set the OrderedSortType to ZSecondaryParentY:

SpriteManager.OrderedSortType = SortType.ZSecondaryParentY;

Using Entities to Set Sprite Origin

For Sprites, the sorting is performed according to the sprite's parent. This allows sorting to be performed at a point other than the Sprite's origin (center) for more natural sorting. For example, consider a game with units with different sizes. In this situation, developers are advised to align the Sprite objects to the bottom of the entity. For example, the red X marks the origin of the entity:

If these origins are used, then units will sort properly according to where they are "standing" as shown in the following image:

IDrawableBatch Sorting Details

The name ZSecondaryParentY suggests that objects are sorted by their Z value, then secondarily by their parents' Y value. Using a parent object (such as an entity) to control the sorting of a Sprite is useful (as shown above). Although IDrawableBatch implementations can have parents (especially if inheriting PositionedObject), IDrawableBatches are not required to have a parent. Therefore, the secondary sorting for IDrawableBatch instances is done by the Y property. While this limitation prevents using entities to set the origin of an IDrawableBatch, this can be resolved by offsetting the rendering of an IDrawableBatch so that its position marks its bottom. Furthermore, IDrawableBatch instances and Sprite will sort within the same category using Y values, but then Sprite vs. IDrawableBatch rendering is only performed by the Z value, even if the sort type is set to ZSecondaryParentY. If your game requires sorting Sprite vs. IDrawableBatch instances, you may need to adjust their Z value to force a particular sorting rather than relying on the Z value, or you may need to move all of your rendering to one type of object (either all Sprite or all IDrawableBatch).

Example with default OrderedSortType

The default OrderedSortType is SortType.Z. This sort type will result in Sprites overlapping incorrectly with the above example. To see the difference, replace the above code with:

 for (int i = 0; i < 10; i++)
 {
     Sprite sprite = SpriteManager.AddSprite("redball.bmp");
     sprite.Y = - 15 + 3 * i;
     sprite.ScaleX = sprite.ScaleY = 12f;
     sprite.RotationX = 1.57f;
 }

 // SortType.Z is the default value, but we'll explicitly set it anyway
 SpriteManager.OrderedSortType = SortType.Z;

Since all Sprites have an equal Z value (default of 0), then they are drawn in the order that they were added to the SpriteManager; from bottom-up. That means that the Sprites seen from below (at the top of the screen) will appear to overlap incorrectly.

CustomComparer

The SortType.CustomComparer allows you to define custom sorting logic for your Sprites. The following shows how to create and use an IComparer that sorts all ordered Sprites along their X axis: Add the following using statement:

using FlatRedBall.Graphics

Add the following to Initialize after initializing FlatRedBall:

for