[SOLVED] Different working on OpenGL and DX

Unity Engine
1

I have this shader, used inside a update loop in this way:

        if ((DateTime.Now - mLastEffectTime).TotalSeconds < 1.0f / EffectRate)
            return;
        
        mLastEffectTime = DateTime.Now;
        mDisperseMat.SetFloat("_AlphaTransmition", AlphaTransferRate);
        mDisperseMat.SetFloat("_ScanOffset", AlphaScanInterval);

        Graphics.Blit(AuxRT, AuxRT, mDisperseMat);

The fragment shader:

float4 frag(pData pixelData) : COLOR
			{
				float4 texCol = tex2D(_MainTex, pixelData.uv);
				if(texCol.w > 0)
				{
					for(int i=-1; i<2; i++)
						for(int j=-1; j<2; j++)
						{
							float2 shiftedUV = pixelData.uv;
							shiftedUV += float2(i*_ScanOffset, j *_ScanOffset);
							float4 nearCol = tex2D(_MainTex, shiftedUV);
							texCol.w -= (1.0-nearCol.a) * _AlphaTransmition;
						}
				}
				
				texCol.w = max(0,texCol.w);
						
				return texCol;
			}

It works perfect on DX, but in OpenGL it seems like just one loop of the Update script is called.
What could be the problem?

(The shader disperses the alpha on a texture).

2

Perhaps using the same texture as the source and destination doesn’t work properly in OpenGL? Have you tried using two different textures?

3

This is correct. You will need to use two textures and ping pong between them as target and source.

4

I was thinking that could be something like that.

I’ll try.

edit: same effect, in DX works pefect but in OpenGL dont work at all.
Sometimes it gives a black texture as a result, and some others dont do anything (in the same execution).

5

PROBLEM SOLVED!

i defined my sampler as a sampler2D, but the texture was a RECT instead (a rendertexture), so the texture wasnt binded by Unity.

I redefined my sampler as a samplerRECT and used texRECT instead of tex2D. (Becarefull cause the uv coordinates used in texRECT are [0-screenWidth, 0-screenHeight] instead of [0-1,0-1]).