float AngleTo(float2 v1, float2 v2, bool clockWise)
{
int sign = clockWise ? -1 : 1;
float a1 = atan2(v1.y, v1.x) * sign;
float a2 = atan2(v2.y, v2.x) * sign;
float a = a2 - a1;
if (a < 0)
{
return 2 * Pi + a; ;
}
return a;
}
public void AngularGradientTest(float4 inputSampler, float2 uv, float2 centerPoint, float startAngle, float arcLength, float4 startColor, float4 endColor, float4 expected)
{
this.inputSampler = inputSampler;
this.CenterPoint = centerPoint;
this.StartAngle = startAngle;
this.ArcLength = arcLength;
this.StartColor = startColor;
this.EndColor = endColor;
float4 c = main(uv);
if (distance(expected, c) < 0.01)
{
Assert.Pass();
}
else
{
Assert.AreEqual(expected, c);
}
}
protected static float4 tex2D(float4 inputSampler, float2 uv)
{
return inputSampler;
}
protected static float2 normalize(float2 x)
{
return new float2(x.Normalize(2.0));
}
protected static float2 mul(float2 v, float2x2 m)
{
return new float2(m.Multiply(v));
}
protected static float2 mul(float f, float2 v)
{
return new float2(v.Multiply(f));
}
float4 main(float2 uv)
{
float4 src = tex2D(inputSampler, uv);
if (src.a < 0.01 || abs(ArcLength) < 0.01)
{
return transparent;
}
float2 v = uv - CenterPoint;
float2 vs = mul(float2(1, 0), RotationMatrix(radians(StartAngle)));
float a = degrees(AngleTo( vs,v, ArcLength < 0));
float f = abs(a) < 0.1 ? 0 : a / abs(ArcLength);
if (f < 0 || f > 1)
{
return transparent;
}
float3 rgb = lerp(StartColor.rgb, EndColor.rgb, f);
return float4(rgb, src.a);
}
