Switching on a TV

If you switch on one of those old TVs, it starts out all black. Then there’s a bright white spot in the center which quickly spreads out all over the TV and then slowly the image fades in.

I want to use that for a model in Blender but i’m not sure on how to do it, or if it’s even possible inside Blender. Do i have to make an animated image texture in some external program for that? Any feedback would be appreciated.


Looks like you can set up an IPO curve for a texture and a material, so it should be possible. Make two planes, one for the image, on top, and set the alpha to zero so it’s transparent. Give the underneath plane a spherical blend texture, and turn down the brightness to get a white spot in the middle. Animate the brightness of the underneath texture, increasing brightness until the spot gets large, then increase the alpha value of the top plane so the image fades into view, hiding the white spot.

You might be able to do it with a single plane, and a stencil texture in between the spot texture and the image texture. That way you could avoid rendering with transparency.

Thanks for the hint. I’m going to try that and come back here to complain, if it didn’t work out. :wink:

I’m not sure what you mean with the stencil texture in the 2nd part though.

Here’s the blender wiki on stencils.

What they don’t mention is that the stencil texture is usually used between two other textures, to let the underlying texture to show through the texture on top, based on the stencil which is sandwiched between them on the texture stack.

Another tricky bit is that blender evaluates the texture stack starting at the top, so the “top” texture on the object is the lowest on the texture stack, and the “underlying” texture on the object is higher up in the texture stack.

Ok. So i got my material that looks like the switching on, and i got my material that looks like when there’s no tv signal but only noise. So far, so good.

Now how the heck can i blend from one of those materials (textures) to the other on the same mesh? I can’t seem to figure it out. :frowning:

Animating alpha blends out the whole mesh.

P.S.: Somesthing like this: http://blenderartists.org/forum/showthread.php?t=102622. Unfortunately he didn’t get any replys which strikes me with fear tbh. :confused:

I see. Alpha is associated with the material, not the texture. Try animating the brightness of the stencil texture.

Actually, i used a blend texture to animate that switch-on part since i wasn’t getting any results with a stencil texture. :o I animated it’s brightness and contrast values to get the desired effect.

The other animation is just an animated noise texture, repeating over 2 frames.

Would it help if i post the .blend?