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# Adding thickness of plane figures

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Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.

7 replies to this topic

### #1Yura  Members

Posted 14 February 2013 - 06:24 AM

Hi,

I'm rendering many geometric figures on scene at once, using primitives. Some of those figures are solid (thick) and contain 6 (for solid triangle) or 8 (for cubes) points. And some of figures are plane - priangle (3 poins) and rectangle (4 points). I'm using vertex buffer with ready-made points   and just render it to the device.

So, my objective is to make plane figures thicker, another words - objects, which contain 3 or 4 points must not be plane. Rectangle must become a cube, but cube (figure with 8 points) must not be changed.

Some ideas, how can I do it? I thought adding extra points will be a good solution, but how can I calculate which point to add if my VertexBuffer is not sorted?

Attaching some pictures:

upper surface is plane, otger - solid

upper solid

now with lines, solid figures has 6 or 8 points, plane has 3 or 4

How to make plane objects to be as thick as solid ones?

### #2Jason Z  Members

Posted 14 February 2013 - 08:43 PM

There is no easy way to do this unless you marked the vertices to be expanded with a special vertex attribute.  Do you have access to the geometry before it gets loaded into the buffers?  If so, you should do that on your CPU before the data gets uploaded to the GPU.

Jason Zink :: DirectX MVP

Direct3D 11 engine on CodePlex: Hieroglyph 3

Games: Lunar Rift

### #3Yura  Members

Posted 15 February 2013 - 01:28 AM

There is no easy way to do this unless you marked the vertices to be expanded with a special vertex attribute.  Do you have access to the geometry before it gets loaded into the buffers?  If so, you should do that on your CPU before the data gets uploaded to the GPU.

Yes, I have an access to the data before loading it's to VertexBuffer,  but I onle have 2 files, in first - vertices (ID, X, Y, Z), in second - indices (in what sequence should I connect those vertices by ID).

What "special attribute" you are talking about?

### #4Yura  Members

Posted 19 February 2013 - 03:00 AM

There is no easy way to do this unless you marked the vertices to be expanded with a special vertex attribute.  Do you have access to the geometry before it gets loaded into the buffers?  If so, you should do that on your CPU before the data gets uploaded to the GPU.

Jason, do not leave me alone with this)

### #5Jason Z  Members

Posted 19 February 2013 - 07:01 AM

There is no easy way to do this unless you marked the vertices to be expanded with a special vertex attribute.  Do you have access to the geometry before it gets loaded into the buffers?  If so, you should do that on your CPU before the data gets uploaded to the GPU.

Jason, do not leave me alone with this)

Sorry, I didn't see this post...

What I meant was that you could add another attribute to your vertex layout, which could indicate to your pipeline that a particular set of vertices needs to be expanded to be thicker.  This would be something like an integer value in your vertices that when it was 1 you would do the expansion, and when it was 0 you wouldn't.  That could be carried out in the GS, but would likely not be all that efficient.

I would recommend just doing this as a pre-processing step.  That way you can verify the results at design time, and not have to perform any inefficient rendering techniques at runtime.

Jason Zink :: DirectX MVP

Direct3D 11 engine on CodePlex: Hieroglyph 3

Games: Lunar Rift

### #6Yura  Members

Posted 20 February 2013 - 02:32 AM

There is no easy way to do this unless you marked the vertices to be expanded with a special vertex attribute.  Do you have access to the geometry before it gets loaded into the buffers?  If so, you should do that on your CPU before the data gets uploaded to the GPU.

Jason, do not leave me alone with this)

Sorry, I didn't see this post...

What I meant was that you could add another attribute to your vertex layout, which could indicate to your pipeline that a particular set of vertices needs to be expanded to be thicker.  This would be something like an integer value in your vertices that when it was 1 you would do the expansion, and when it was 0 you wouldn't.  That could be carried out in the GS, but would likely not be all that efficient.

I would recommend just doing this as a pre-processing step.  That way you can verify the results at design time, and not have to perform any inefficient rendering techniques at runtime.

What I did till now is just doubling vertices in plane figure, otherwords - added additional points. It seems to be not bad, BUT I must have a possibility to enable/disable thickness of plane figures during runtime. Using this method I must rewrite my vertexBuffer each time I call enable or disable thickness. Enable - rewrite with additional points, disable - rewrite "as is".  Other problem - if I have very big model and adding extra points to it, it is very hard then to build indexBuffer, becouse each element contain some vertices, wich are not sorted by phisical index, only by ID, so, it is hard to work with locked vertexBuffer, couse in that way I have an access only to phisical indexes of each vertex. If I'm adding extra points, their phisical index is shifted...

I need some effective algorithm to do this "pre-processing step"..

Edited by Yura, 20 February 2013 - 04:06 AM.

### #7Jason Z  Members

Posted 21 February 2013 - 09:09 PM

Sorry, but I don't see any easy way to get around the issue...  Is it possible to move the geometry that can be enabled / disabled to another vertex buffer - or even to a special portion of the vertex buffer that would help you keep the indices manageable?

If the plane pieces are normally the same size, you could also try using instancing to render the expandable parts.  When thickness is disabled, you render using a thin plane as your per vertex data, and when it is enabled, you could switch the data to include the thicker version.  That would actually work out pretty easy I think...  Does that sound possible?

Jason Zink :: DirectX MVP

Direct3D 11 engine on CodePlex: Hieroglyph 3

Games: Lunar Rift

### #8Yura  Members

Posted 22 February 2013 - 02:20 AM

Sorry, but I don't see any easy way to get around the issue...  Is it possible to move the geometry that can be enabled / disabled to another vertex buffer - or even to a special portion of the vertex buffer that would help you keep the indices manageable?

If the plane pieces are normally the same size, you could also try using instancing to render the expandable parts.  When thickness is disabled, you render using a thin plane as your per vertex data, and when it is enabled, you could switch the data to include the thicker version.  That would actually work out pretty easy I think...  Does that sound possible?

I figured out with this by adding extra points in the end of my vertexBuffer and build 2 indexbuffers: first without additional points - normal model, second with additional points - thick figures. Using ON/OFF thickness I'm just changing index buffers and render model.

Thanks for help Jason!

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