Make dripping compatible with Flow Maps about inkpainter HOT 2 CLOSED

I don't have too much experience in shaders but I'm making some test on my own, i changed the HeightDrip.shader shader, i've replaced FlowDirection with a Flow map texture, with it's corresponding texture sampler.

sampler2D _MainTex;
sampler2D _FlowTex;
float4 _MainTex_ST;
float4 _MainTex_TexelSize;
float4 _FlowTex_TexelSize;

float2 getNormalizedFlowPoint(float2 uv)
{
	return float2 (tex2D(_FlowTex, uv).rg * 2.0f - 1.0f);
}
...
float2 shiftZ = float2(getNormalizedFlowPoint(i.uv).x * _FlowTex_TexelSize.x, getNormalizedFlowPoint(i.uv).y * _FlowTex_TexelSize.y) * _ScaleFactor * _Viscosity * VITIATE_Z;
float2 shiftX = float2(_FlowTex_TexelSize.x * getNormalizedFlowPoint(i.uv).y, _FlowTex_TexelSize.y * getNormalizedFlowPoint(i.uv).x) * _ScaleFactor * _Viscosity * VITIATE_X;
float2 shiftx = -shiftX;

And i'ts working almost right, but i have a problem, when i specify a totally gray map RGB(0.5,0.5,0.5,1), even when the flow shouldn't move, it start drifting slightly to to upper right corner (in a test plane, at the UV coordinates 1,1)

if it's help in something, i could add a PR with my modifications to the 'Still not working completelly' HeightDrip shader, and the test Flowmaps textures to recreate the testing case.

from inkpainter.

very pleased to cooperate to make InkPainter better.
pull requests are always welcomed.
thank you!

from inkpainter.