Shifting a sprite's texture

Unity Engine
1

Hi there,
I have created a simple shader to shift the texture on a sprite.

float4 frag(Fragment IN) : COLOR
             {
                IN.uv_MainTex.x += _ScrollX;
                IN.uv_MainTex.y += _ScrollY;
                half4 c = tex2D (_MainTex, IN.uv_MainTex);  
                return c;
             }

The result can be seen below.
The texture is shifted allright, but at the borders no wrap around occurs. Instead the pixels seem to be duplicated.

Is there a way to fix this (i.e. make the texture repeat)?

2309569--155602--Shader.jpg

2

Have you tried setting the Wrap Mode to Repeat on the texture itself?
2309960--155615--wrapmode.jpg

3

The sprite textures do not have this setting :frowning:

I almost solved the problem by using the following shader code:

float4 frag(Fragment IN) : COLOR
             {
                 IN.texcoord.x += _ScrollX;
                IN.texcoord.y += _ScrollY;
            
                 if(IN.texcoord.x >= 1.0f)
                     IN.texcoord.x -= 1.0f;
                 if(IN.texcoord.x < 0.0f)
                     IN.texcoord.x += 1.0f;
            
                 if(IN.texcoord.y >= 1.0f)
                     IN.texcoord.y -= 1.0f;
                 if(IN.texcoord.y < 0.0f)
                     IN.texcoord.y += 1.0f;
                    
                half4 c = tex2D (_MainTex, IN.texcoord);  
                return c;
             }

Only one problem remains: There is a small but ugly seam where the wrap-around occurs (see screenshot).
I would be very thankful for any advice on how to get rid of this…

2310104--155633--Seam.jpg

4

try this instead:

float mod (float x, float y){
    return x - y * floor(x/y);
}

float4 frag(Fragment IN) : COLOR
{
    IN.texcoord.x = mod(IN.texcoord.x + _ScrollX, 1.0);
    IN.texcoord.y = mod(IN.texcoord.y + _ScrollY, 1.0);
            
    half4 c = tex2D (_MainTex, IN.texcoord);
    return c;
}
5

Definitely more elegant :slight_smile:
But your code seems to do the same thing as mine (the seam still exists).

6

This is an artifact of mipmapping. If you can turn off mipmaps this should go away.

7

Yep, that solved it.
Thanks a bunch :slight_smile: