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)); }