I use Unity, and I need a shader a bit special. Unfortunatly my skills about shaders are very limited and I need this shader quickly.
So I want a shader to display a unlit texture on a plane, and when a light affect the plane, instead of make the lighting on the plane, I want that the light change the alpha to make the "lighted" surface transparent.
I think that it's not very hard for someone who know how to make shaders, so if you can help me to do this, it can be very useful for me ! Thanks in advance
Edit:
Ok, maybe it's not very clear.
I speak about a light, but it's not necessary a light, it can be with an other type of object, or just a position.
What I want is to have an unlit image, with a movable circle zone on this texture which make the zone transparent, like the white circle on this picture (imagine that the with is just the transparency).
The border shouldn't be necessarily with smooth border, it will be also fine with an hard border.
I have thought about a spotlight, because it's like move a spotlight on the picture, but instead of doing the lighting, I want to set the "lighted" pixel transparent (but it's not lighted, it's just to explain what I want), a,d it's not necessary with a light
And yes, the unlit shader can't do this I think, I probably need a custom shader but I don't know how to this (I have thinked about take a basic lighting shader, and use the computed intensity of the light on the pixels to set the alpha instead of use it to set the intensity of the pixel, but I don't know exactly how to do this)
