Transparent png layer rendering strangely

Transparent png layer rendering strangely

Hi there,

First off, I'm a very infrequent Cheetah 3d user. I love the program, but because I'm still very inexperienced in 3d modelling I quite often hit stumbling blocks when I attempt to use it.

I hope someone will be able to steer me in the right direction on this issue (I'm sure there's an obvious answer that a newbie like me can't see).

I'm attempting to mock up a shiny mug, with an overlay PNG design.

The mug and handle have a reflective blue material. The image/decal overlay is wrapped on a curved overlay of polygons (duplicated from one side of the mug) that is pulled very slightly out from the body of the mug so that it sits just over the gloss surface.

When I render the mugs without the image decal, they look fine (or as fine as my rubbish modelling skills allow... ;-) )

When I place the image overlay on top, the blending immediately surrounding the decal appears fine, but the rest of the mug is suddenly shrouded in black. Why might this be?

The image's material transparency has the box ticked to 'Use alpha channel', so hopefully this uses the PNG's alpha, rather than me having to create one from scratch.

Am I missing something obvious?

Thanks in advance for any help.

Hi.
When you use alpha channel you will look through its transparency.
I´d use the composite node like shown in the image:
Use 1 material for the diffuse color and the same with the additional composite node on the selected polygons - you might need to check the UV-editor for final adjustments - but the set-up is pretty straight forward.

Cheers
Frank

Hi Frank,

Thanks for the reply. I haven't dug into the node editor yet (was a little frightened by it at first!)

That looks reasonably straight forward, though.

So using this method, I'd be able to lose the extra polygons (with decal layer) hovering in front of the mug? Just maybe have that section split as a child of the mug, with the two separate materials: one the straight gloss, applied to the mug, and one with the gloss and the decal combined in the node applied to the child section cut-out?

I'll give it a go. Thanks for the tip

2 versions:
A: If you use a split portion with the decal only you have to move it a fraction from the surface (it can´t stay in the same place for the render engine; z-depth chasing) A light source in your scene needs raytrace&trans enabled at the shadow part to maintain light rays go through the alpha channel.
B: just select a polygon portion and drag your composite material onto it - final adjustments via UV-editor with editable texture to see what you´re doing.

Cheers
Frank

Hi Frank,

Great. That's working really well.

The only issue I'm having is that I can't see the texture until I render.

Is there a way that I can preview it (even at low res) while in the Modelling/UV Editing mode, so that I can get the scale/stretch of the decal in the right ratio?

Thanks

Every image that´s driven by nodes is no longer displayed in 3d-view.
That´s why I suggest to hit "Edit" button at the image loader when in UV-editor:

Cheers
Frank

PS: You can override the composite node for the time being by connecting image->diffuse channel while adjusting proportions.

I did leave that selected, but it wasn't showing in the 3d display like it does in your example above.

Thanks for your time on this. Apologies if I'm being stupid!

That´s why I added a postscript-um about an override already:

Cheers
Frank
Another PS: normally you´d UV unwrap that portion - export to PDF - make the texture - load image - bingo.

Aha! So much to learn

Thanks.