54 lines
2.3 KiB
C#
54 lines
2.3 KiB
C#
|
using Unity.Collections.LowLevel.Unsafe;
|
||
|
|
using UnityEngine.Experimental.Rendering;
|
||
|
|
|
||
|
|
namespace UnityEngine.InputSystem.Utilities
|
||
|
|
{
|
||
|
|
internal static class SpriteUtilities
|
||
|
|
{
|
||
|
|
public static unsafe Sprite CreateCircleSprite(int radius, Color32 colour)
|
||
|
|
{
|
||
|
|
// cache the diameter
|
||
|
|
var d = radius * 2;
|
||
|
|
|
||
|
|
var texture = new Texture2D(d, d, DefaultFormat.LDR, TextureCreationFlags.None);
|
||
|
|
var colours = texture.GetRawTextureData<Color32>();
|
||
|
|
var coloursPtr = (Color32*)colours.GetUnsafePtr();
|
||
|
|
UnsafeUtility.MemSet(coloursPtr, 0, colours.Length * UnsafeUtility.SizeOf<Color32>());
|
||
|
|
|
||
|
|
// pack the colour into a ulong so we can write two pixels at a time to the texture data
|
||
|
|
var colorPtr = (uint*)UnsafeUtility.AddressOf(ref colour);
|
||
|
|
var colourAsULong = *(ulong*)colorPtr << 32 | *colorPtr;
|
||
|
|
|
||
|
|
float rSquared = radius * radius;
|
||
|
|
|
||
|
|
// loop over the texture memory one column at a time filling in a line between the two x coordinates
|
||
|
|
// of the circle at each column
|
||
|
|
for (var y = -radius; y < radius; y++)
|
||
|
|
{
|
||
|
|
// for the current column, calculate what the x coordinate of the circle would be
|
||
|
|
// using x^2 + y^2 = r^2, or x^2 = r^2 - y^2. The square root of the value of the
|
||
|
|
// x coordinate will equal half the width of the circle at the current y coordinate
|
||
|
|
var halfWidth = (int)Mathf.Sqrt(rSquared - y * y);
|
||
|
|
|
||
|
|
// position the pointer so it points at the memory where we should start filling in
|
||
|
|
// the current line
|
||
|
|
var ptr = coloursPtr
|
||
|
|
+ (y + radius) * d // the position of the memory at the start of the row at the current y coordinate
|
||
|
|
+ radius - halfWidth; // the position along the row where we should start inserting colours
|
||
|
|
|
||
|
|
// fill in two pixels at a time
|
||
|
|
for (var x = 0; x < halfWidth; x++)
|
||
|
|
{
|
||
|
|
*(ulong*)ptr = colourAsULong;
|
||
|
|
ptr += 2;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
texture.Apply();
|
||
|
|
|
||
|
|
var sprite = Sprite.Create(texture, new Rect(0, 0, d, d), new Vector2(radius, radius), 1, 0, SpriteMeshType.FullRect);
|
||
|
|
return sprite;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|