CODEWITHSUNDEEP
c++opengl
kbz
kbz

Reputation: 1006

How would I go about applying a skybox to the world, openGL C++

I'm trying to add a skybox to the world/camera/game and I don't know how to go about it. If someone could give me some guidance on how to apply it, it would be much appreciated.

I have already loaded the skybox, I just don't know how to draw it properly so it will fit around the camera as it moves.

I have managed to texture a sort of cube, which might be close to a skybox but then it's only visible from the outside. Once you enter the cube, you can't see it from the inside. Perhaps if I could invert the cube's faces, it will show when I'm inside the cube and I can make it larger?

From outside the cube looking at it enter image description here From inside looking out enter image description here

Upvotes: 1

Views: 857

Answers (1)

Halfpint
Halfpint

Reputation: 4079

I had a similar problem a few weeks back, if you are looking for some pseudo code I think I may be able to help. First of all using a cube isn't the best idea when rendering as your box won't look natural, map it to a sphere for a smooth effect.

  1. Create a bounding sphere around your viewer that moves relative to your camera

  2. Apply the texture on that sphere, this will give the impression that the sky is moving relative to you

  3. When you are drawing, disable your z-buffer and frustum (assuming you're using any culling algorithm) this will allow the sky box to be drawn but will ensure terrain is drawn over the top of the sky box when depth sort algorithms are performed by OpenGL.

Note: Don't forget to re-enable the z-buffer after the sky box has been drawn, otherwise your terrain elements will appear outside of the sphere, meaning you will only see the Sky box.

I recently wrote a basic terrain engine in DirectX but the principals are fairly similar, if you'd like to view the repo you can find it here

Check out line 286 in this file to see how the Skybox is rendered, then also visit the SkyBox implementation file to see how it is constructed, and the SkyShader implementation file to see how the texture is mapped to the sphere, the main method to be concerned with in the shader file is SetShaderParameters()

In terms of moving the skybox relative to your camera, simply set the WVP matrix of your skybox to that of your camera, and then tweak the x, y, z planes of the skybox to your liking.

Extra If you are going to implement multi-player aspects, just disable back-face rendering for the sphere, then each player can see their SkyBox but opponents cannot. Alternatively you create one large sphere around the world

Hope that helps - if you need anymore help just ask, I know this stuff can be fairly dense at first:)

Upvotes: 3

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