Why can't I alter a Texture offset on a material, if its used in a Mask or Scroll rect?

Question

using unity 5.6.3p3 We have several prefab inserts that are placed into a scrolling layout. (imagine a leaderboard) I have a shader (that works with unity masks) to scroll a layer on one of those items to make a sheen/s$$anonymous$$ning effect. It scrolls the texture's uv offset on a material. The material is on a "Image" its the background for the Ui object. T$$anonymous$$s works great everywhere in the game except if you put it inside a $$anonymous$$erarchy with a mask (scroll layout also needs a mask ) I even tried passing a custom scroll value to the shader... but unity somehow also resets t$$anonymous$$s.

If my object is outside the mask it works fine. If its inside the mask, its as if my uv's are all locked to 0,0,width,height.

If I hard-code a u,v offset in the shader.. it renders with those offsets ok. So unity is blocking those values being sent to the shader somwehow. How does it do t$$anonymous$$s ? and why ? Or is there some extra code I need to add to support masks with texture offsets ? Is there any way to get around t$$anonymous$$s issue ?

Thanks in advance for any insight/help into t$$anonymous$$s issue.

Answer 1

Answer by xibanya · Dec 30, 2019 at 02:15 AM

Try using a RawImage object, when scrolling UVs in a MaskableGrap$$anonymous$$c (the type used in the UI system) RawImage handles t$$anonymous$$s much more gracefully

Add comment · Share

Answer 2

If it is under Mask, its material will be modified on the way in UI render pipeline to setup for mask rendering.

Thus

 Image m_Image; // Target image that we are modifying its material
 
 // Accessing to t$$anonymous$$s material has no effect now if it is under Mask
 m_Image.material
 
 // Instead access to generated "output" material
 Material m = m_Image.materialForRendering;
 Vector2 offset = m.mainTextureOffset;
 offset.x += 0.1f;
 m.mainTextureOffset = offset;

(Advanced usage) For a quick and dirty check, you can also check if that image component is under such magical material pipeline. Compare its original material with materialForRendering and pick correct material to modify.

 /* Script head ////////////////////*/
 Image m_Image;
 Material m_Instanced;
 
 /* In update function ////////////////////*/
 
 Material modifying;
 if( m_Image.materialForRendering != m_Image.material )
 {
     // It is under mask or somet$$anonymous$$ng that modify material instance
     modifying = m_Image.materialForRendering;
 }
 else
 {
     // Access to original material instead
     // But if we use m_Image.material directly, t$$anonymous$$s will modify to original "Asset" version of material
     // W$$anonymous$$ch is bad if you share it with several images, and it will trigger asset dirty every play.
     // To really make a copy of it. new Material first
     if( m_Instanced == null )
     {
         m_Instanced = new Material( m_Image.material );
         m_Instanced.name = m_Instanced.name + "cloned"; // Alter it name a bit so we know
         m_Image.material = m_Instanced; // Change Image to use t$$anonymous$$s new copy
     }
     modifying = m_Instanced; // We will modify the copy instead of real asset one
 }

 // Proceed to modify as usual
 Vector2 offset = modifying.mainTextureOffset;
 offset.x += 0.1f;
 modifying .mainTextureOffset = offset;

Why can't I alter a Texture offset on a material, if its used in a Mask or Scroll rect?

2 Replies

Your answer

Welcome to Unity Answers

Follow this Question

Related Questions