public void AlphaBlendStateIsValid()
{
// Arrange.
var device = new Device();
var blendState = new BlendState(device, BlendStateDescription.AlphaBlend);
var source = new Number4(1.0f, 0.0f, 0.0f, 0.3f);
var destination = new Number4(0.0f, 1.0f, 0.0f, 0.4f);
var blendFactor = new Number4();
// Act.
var result = blendState.DoBlend(0,
ref source, ref destination,
ref blendFactor);
// Assert.
Assert.That(result.R, Is.EqualTo(1.0f).Within(0.01f));
Assert.That(result.G, Is.EqualTo(0.7f).Within(0.01f));
Assert.That(result.B, Is.EqualTo(0.0f).Within(0.01f));
Assert.That(result.A, Is.EqualTo(0.3f + (1 - 0.3f) * 0.4f).Within(0.01f));
}