Only draw visible objects to the camera in 2D
- by Deukalion
I have Map, each map has an array of Ground, each Ground consists of an array of VertexPositionTexture and a texture name reference so it renders a texture at these points (as a shape through triangulation).
Now when I render my map I only want to get a list of all objects that are visible in the camera. (So I won't loop through more than I have to)
Structs:
public struct Map
{
public Ground[] Ground { get; set; }
}
public struct Ground
{
public int[] Indexes { get; set; }
public VertexPositionNormalTexture[] Points { get; set; }
public Vector3 TopLeft { get; set; }
public Vector3 TopRight { get; set; }
public Vector3 BottomLeft { get; set; }
public Vector3 BottomRight { get; set; }
}
public struct RenderBoundaries<T>
{
public BoundingBox Box;
public T Items;
}
when I load a map:
foreach (Ground ground in CurrentMap.Ground)
{
Boundaries.Add(new RenderBoundaries<Ground>()
{
Box = BoundingBox.CreateFromPoints(new Vector3[] { ground.TopLeft, ground.TopRight, ground.BottomLeft, ground.BottomRight }),
Items = ground
});
}
TopLeft, TopRight, BottomLeft, BottomRight are simply the locations of each corner that the shape make. A rectangle.
When I try to loop through only the objects that are visible I do this in my Draw method:
public int Draw(GraphicsDevice device, ICamera camera)
{
BoundingFrustum frustum = new BoundingFrustum(camera.View * camera.Projection);
// Visible count
int count = 0;
EffectTexture.World = camera.World;
EffectTexture.View = camera.View;
EffectTexture.Projection = camera.Projection;
foreach (EffectPass pass in EffectTexture.CurrentTechnique.Passes)
{
pass.Apply();
foreach (RenderBoundaries<Ground> render in Boundaries.Where(m => frustum.Contains(m.Box) != ContainmentType.Disjoint))
{
// Draw ground
count++;
}
}
return count;
}
When I try adding just one ground, then moving the camera so the ground is out of frame it still returns 1 which means it still gets draw even though it's not within the camera's view.
Am I doing something or wrong or can it be because of my Camera?
Any ideas why it doesn't work?
