Render the borders of quads from GLModel

kosowski

Render the borders of quads from GLModel

in Contributed Library Questions • 5 months ago

Hi,

I have a GLModel of quads with different colours and normals, and I would like to have the border of each quad drawn in a different colour, like having different stroke() and fill() colours. Something like this:

I have tried playing with stroke(), fill(), noFill() and model.setLineWidth() with no succes, is this possible at all with GLModel?

Another solution would be to create a GLMode lof LINES with just the borders and render it on top of the other GLModel. Would the modes LINE_STRIP or LINE_LOOP reduce the number of vertex, as with LINES I would need to duplicate lots of vertex?

Thanks!

Replies(3)

amnon.owed

Re: Render the borders of quads from GLModel

5 months ago

No, you can't change a GLModel's display type once it's created. As you mention, the easiest workaround is to create two identical GLModels (one for the fill, one for the lines). I've used this method myself for this video. You could also use a shader to render the model differently the second time around (aka as just white lines). This should be relatively easy, since it's a grid, so you can use either the position or the texture coordinates to do this. You could also opt for direct opengl calls if you know your way around low level opengl.

I think PShape from Processing 2.0b8 actually facilitates what you want out-of-the-box.

kosowski

Re: Render the borders of quads from GLModel

5 months ago

Thanks amnon!

I didn't realize there was a shader solution and it should be prety easy, but I will try to add a second model as I prefer being able to add borders not to each quad but to groups of several adjacent ones.

I was thinking I could lower the vertex duplication in the LINE model by creating just two lines for each QUAD, say the right and top borders. In this case I would get a grid without the outer bottom and left borders.

I have tried switching to Processing 2.0b8, but porting all the project brought too many problems, especially with the new XML object.

amnon.owed

Re: Render the borders of quads from GLModel

5 months ago

Whatever works!

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