Troubleshooting – Graphics | Forum | sky looks distorted when using SkyFactory.createSky with spheremap |

sky looks distorted when using SkyFactory.createSky with spheremap (17 posts)

Topic tags: graphics, sky, spheremap

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zuperkeurz said 3 months, 2 weeks ago:

Hi, When using the SkyFactory with a spheremap the sky looks heavily distorted. I searched the tests for an example and found a similar issue in the TestEverything test. Here too the cathedral loos distorted.

Ill try to attach an image to show what I see on my screen.

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zuperkeurz said 3 months, 2 weeks ago:

Here is the view for the TestEverything test. As you can see part of the sky is relatively recognizable, but the rest is heavily distorted.

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enum20p said 3 months, 2 weeks ago:

Could you post a little bit of code? That would help finding the error and I’m interested in using that effect^^

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polygnome7p said 3 months, 2 weeks ago:

That Test is part of jME, just look at the jME sources.

I can confirm that this tests looks that way.

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normen1290p said 3 months, 2 weeks ago:

It always did, I don’t think its a bug but rather the wrong type of map.

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zuperkeurz said 3 months, 2 weeks ago:

normen, do you know of a texture that would work? I tried different spheremaps and it always looks distorted.

That’s actually why I took one of the samples, expecting it to work and being well understood.

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normen1290p said 3 months, 2 weeks ago:

If I did I would know it and not just think it

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zuperkeurz said 3 months, 2 weeks ago:

point made

So, basically at this point I see no prove of the spheremaps working in combination with the SkyFactory.

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zuperkeurz said 3 months, 2 weeks ago:

ok it’s a bug. I tested with another spheremap where i noticed repeating patterns. (saw 2 suns in my world where there was only 1 in the spheremap)

In fact, I only posted a single screenshot of the distorted part before (which i call north, it is the default cam orientation). If I turn around in my world, I see some other distortions but they are more subtle.

http://imgur.com/LJy4V

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zuperkeurz said 3 months, 2 weeks ago:

In the image, i labeld 4 screenshots: North, south, ceiling and floor. If you look at the north screenshot, although difficult to spot. it actually repeats the scene. You can see the cathedral’s dome, the floor and monument repeated in there.

It seems for the “north” we are looking at the outside of the sphere, while for the other parts we are looking at the inside of the sphere.

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zuperkeurz said 3 months, 2 weeks ago:

ok more analysis.
The north hemisphere is actually the spheremap texture itself. The distortions is where the spheremap is black or with other words empty

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nehon591p said 3 months, 2 weeks ago:
Actually i found an issue in the sky shader

you have this in the frag shader
```
   vec3 dir = normalize(direction);
    gl_FragColor = Optics_GetEnvColor(m_Texture, direction);
```
the dir variable is never used….
then in Optics_GetEnvColor you have
```
 // compute 1/2p
    // NOTE: this simplification only works if dir is normalized.
    float inv_two_p = 1.414 * sqrt(dzplus1);
```
The problem is if I use the normalized direction, the distortion is worse….

@Momoko_Fan any input on this?
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zuperkeurz said 3 months, 2 weeks ago:

damn, you just beat me to it. tried the same thing.

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pspeed815p said 3 months, 2 weeks ago:
```
// NOTE: this simplification only works if dir is normalized.
float inv_two_p = 1.414 * sqrt(dzplus1);
//float inv_two_p = sqrt(dir.x * dir.x + dir.y * dir.y + dzplus1 * dzplus1);
```
What happens if you flip it back to the old “unoptimized” way?

I can’t really make that math line up to being the same… but I haven’t tried very hard and I’m sleepy.
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zuperkeurz said 3 months, 2 weeks ago:

different distortion towards the pole, similar to when using the normalized direction in the fragment shader. (looks exactly the same, but difficult to tell ofcourse) Which would be inline with your comment regarding normalization.

Im new to shaders and everything, but I don’t get how normalizing the normalin the fragmend shader could have any effect. The vertex shader already normalized that parameter in Sky.vert. So it seems normalization does not occur there in the vector shader? Does it need an out modifier for that parameter perhaps? (tried it, nothing changes)

Why does normaling the vector in the vertex shader doest not impact the fragment shader?

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