/// <summary>
/// Blend other texture as overlay.
/// </summary>
/// <param name="source">The texture background. </param>
/// <param name="overlay">The texture overlay. </param>
/// <param name="overlayPosition">The position that overlay texture will be blended in background texture. </param>
/// <param name="depth">Number of bits in depth buffer (0, 16 or 24). Note that only 24 bit depth has stencil buffer.</param>
/// <param name="canvasRenderTextureFormat">The texture format of canvas render texture. </param>
/// <returns>The texture that has blended background texture and overlay texture.</returns>
/// <exception cref="ArgumentNullException"><c>overlay</c> is <c>null</c>. </exception>
public static Texture2D BlendTextureOverlay(
this Texture2D source,
Texture2D overlay,
Vector2Int overlayPosition,
int depth = 0,
RenderTextureFormat canvasRenderTextureFormat = RenderTextureFormat.ARGB32)
{
if (!overlay)
{
throw new ArgumentNullException(nameof(overlay));
}
if (SystemInfo.supportsComputeShaders)
{
var renderTexture = new RenderTexture(source.width, source.height, depth, canvasRenderTextureFormat)
{
enableRandomWrite = true
};
renderTexture.Create();
var shader = Resources.Load <ComputeShader>("Shaders/BlendTextureOverlay");
var kernel = shader.FindKernel("blendTextureOverlay");
shader.SetTexture(kernel, "source", source);
shader.SetTexture(kernel, "overlay", overlay);
shader.SetInts("overlayDimensions", overlay.width, overlay.height);
shader.SetInts("overlayPosition", overlayPosition.x, overlayPosition.y);
shader.SetTexture(kernel, "canvas", renderTexture);
shader.Dispatch(kernel, source.width, source.height, 1);
var output = renderTexture.ToTexture(new Rect(0, 0, renderTexture.width, renderTexture.height));
Object.Destroy(renderTexture);
return(output);
}
else
{
Debug.LogWarning($"The platform {Application.platform} do not support compute shader, so blend texture will use CPU to process!");
var output = new Texture2D(source.width, source.height, TextureFormat.RGBA32, false)
{
wrapMode = TextureWrapMode.Clamp
};
for (var x = 0; x < source.width; x++)
{
for (var y = 0; y < source.height; y++)
{
var color1 = source.GetPixel(x, y);
var color2 = Color.clear;
var position = new Vector2Int(x - overlayPosition.x, y - overlayPosition.y);
if (0 <= position.x && position.x <= overlay.width && 0 <= position.y && position.y <= overlay.height)
{
color2 = overlay.GetPixel(position.x, position.y);
}
output.SetPixel(x, y, color1 + color2);
}
}
output.Apply();
return(output);
}
}
