Maximum Vertex Coordinates?

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1 comment, last by BenS1 12 years, 6 months ago
Is there a maximum value to the vertex coordinates used to define a triangle in Direct3D 11?

For example, if my screen resolution is 1920x1200, can I define a triangle with the coords V0(0,0), v1(10000000, 0), V2(0,600) which despite the vast majority of the triangle being off screen, it should pretty much cover most of the top half of the visible screen?

I know this sounds like a strange question, but I'm creating a proceedural landscape generation where what you see is only a small window onto a much bigger world.

I'm assuming there is no limit (Other than the numeric limits of the data type the values are held in). Is this correct?

Thanks
Ben
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There is no other limit than what the floats can store but extremely big triangles will have shaking textures from rounding errors because floats have less precision when the exponent is high. You can hide the edges using distance based fog and let the ground follow the camera.

There is no other limit than what the floats can store but extremely big triangles will have shaking textures from rounding errors because floats have less precision when the exponent is high. You can hide the edges using distance based fog and let the ground follow the camera.


Thanks Dawoodoz, that's what I thought.

I won't actually be using any textures, it'll simply be alpha blended solid triangles on a 16bpp greyscale render target. The output is a displacement map, which will then be an input into the actual landscape generation.

Another question that someone might be able to help with... my lanscapes will be massive (Think Earth sized), but I'm aware of the flaoting point precision problems (I've read "the excellent 3D Engine Design for Virtual Globes" which details this), but given that my engine is DirectX 11 only, is it safe to assume that all DirectX 11 GPUs have to support Double Precision? i.e. is it a requirement of Shader Model 5, or is it optional?

Thanks again
Ben

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