[SlimDX] Changing resolution for MiniTri10 sample screws up aspect ratio.

Graphics and GPU Programming Programming

Started by thr December 27, 2010 08:43 AM

3 comments, last by thr 13 years, 3 months ago

thr

157

Author

December 27, 2010 08:43 AM

I've tried to change the resolution for the MinTri10 (DX10) sample in the SlimDX Samples solution by doing this:

var form = new RenderForm("SlimDX - MiniTri Direct3D 10 Sample") { ClientSize = new Size(1280, 720) };

Everything renders, but the triangle looks stretched due to the aspect ratio becomming funky.

However, doing the same in the MinTri example (DX9) works perfectly:

var form = new RenderForm("SlimDX - MiniTri Direct3D9 Sample") { ClientSize = new Size(1280, 720) };

So what am I missing in the DX10 sample? All the methods/objects that take width/height parameter uses form.ClientSize.Width/Height and I can't see anywhere the aspect ratio is specified directly.

sirob

1,181

December 27, 2010 02:42 PM

The difference between the samples is to be expected - since they use a different technique for rendering. The DX9 sample uses Transformed Vertices (VertexFormat.PositionRhw), which means it is specifying the vertex positions in pixels.

On the other hand, the D3D10 sample uses a simple pass-through shader, which causes the vertices to go through some of the transformation pipeline.

The difference in the behavior when the window is resized is due to the difference in how each sample draws.

Sirob Yes.» - status: Work-O-Rama.

thr

157

Author

December 28, 2010 01:46 AM

Ok, I think I follow. But how would one go about to allow a 16:9 resolution in the DX10 examples?

I noticed that in the SimpleTriangle10 sample (thats using the Sample Framework from the SlimDX Samples) the triangle gets stretched when re-sizing, but the SimpleModel10 (planet + moon) the two models don't.

Edit: Oh stupid me, there is no WVP multiplication in the shader. And that's exactly what you said. Doh. Thanks :)

[Edited by - thr on December 28, 2010 2:46:38 AM]

Washu

7,836

December 28, 2010 02:52 AM

Note that the samples are just that, samples. They show how to initialize and use the SlimDX libraries, but not a heck of a lot more. As such, from a purely functionality point of view, they're pretty poor. But for doing what we request of them which is to show some of the ways to use SlimDX, such as accessing vertex buffers through the stream objects, they are short and to the point.

Also, if you're wondering about the extra bit of code in the SlimModel10 that came with the SDK (and is no longer in the SVN copy), it's just test code. You can safely remove it.

In time the project grows, the ignorance of its devs it shows, with many a convoluted function, it plunges into deep compunction, the price of failure is high, Washu's mirth is nigh.

thr

157

Author

December 28, 2010 02:58 AM

Washu: Yeah, I actually did wonder about that code - I posted a question in these forums a few days ago about it even! :)

The reason the MiniTri10 sample caught me off guard was because I didn't look in the shader.

Thanks both of you for your help! :)

[SlimDX] Changing resolution for MiniTri10 sample screws up aspect ratio.

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[SlimDX] Changing resolution for MiniTri10 sample screws up aspect ratio.

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