I have a 512x512 image which contains 0…15x0…15 images a 32x32.
Then I would like to create a mesh with one of the 32x32 images.
Must I fill the TexCoord buffer with 0…1 values or can I use 0…512 and scale the texture?
Currently I do this:
[java]
texCoord.get(bloxelType).addAll(assetManager.getTextureCoordinates(bloxelType, FACE_BACK));
texCoord.get(bloxelType).addAll(assetManager.getTextureCoordinates(bloxelType, FACE_FRONT));
// … and so on for all six faces of a cube
// then later I create the mesh …
chunkMesh.setBuffer(Type.TexCoord, 2,BufferUtils.createFloatBuffer(texCoord.get(bloxelType).toArray(new Vector2f[texCoord.size()])));
[/java]
The image-atlas code is here:
[java]
private List<Vector2f> uvMapTexture(final Vector2f coord) {
if (coord == null) {
// use complete image as texture
final Vector2f bottomLeft = new Vector2f(0, 0);
final Vector2f bottomRight = new Vector2f(1, 0);
final Vector2f topLeft = new Vector2f(0, 1);
final Vector2f topRight = new Vector2f(1, 1);
return Lists.newArrayList(bottomLeft, bottomRight, topLeft, topRight);
}
// each image is 32x32, the whole image-atlas is 512x512
// coord.x: 0…15
// coord.y: 0…15
final float s = 32f / 512f;
final float x = coord.x * s;
final float y = coord.y * s;
final Vector2f bottomLeft = new Vector2f(x, y);
final Vector2f bottomRight = new Vector2f(x, y + s);
final Vector2f topLeft = new Vector2f(x + s, y);
final Vector2f topRight = new Vector2f(x + s, y + s);
// return Lists.newArrayList(bottomLeft, bottomRight, topLeft, topRight); ??!? each face is 90 degree rotated clockwise
return Lists.newArrayList(topLeft, bottomLeft, bottomRight, topRight); // this looks better but the texture is a little bit stretched
}
[/java]
Here is my image … the good old minecraft texture 
… the grass image have the coordinates up:0,15;down:3,14;left:3,15;right:3,15;front:3,15;back:3,15 (bottom,left=0,0/top,right=15,15)
It looks like two of the coordinates might be swapped… like the top ones. But it’s just a guess since I don’t know what vertexes you are using.
Edit: I’m 99% sure that’s what it is. The texture is mirrored along the diagonal where the triangles split the quad.
looks like the top 2 and bottom 2 have been entered back to front ?
I’m guessing this will do it :
[java] final Vector2f bottomLeft = new Vector2f(x, y);
final Vector2f bottomRight = new Vector2f(x+s, y);
final Vector2f topLeft = new Vector2f(x, y+s);
final Vector2f topRight = new Vector2f(x + s, y + s);[/java]
good luck
Thanks guys … but now its looks like this:
I think I’m understanding the concept of custom mesh (the basics)
But this texture-buffer-stuff is a miracle to me :-[Can someone please post a advanced texture example in the documentation. The documentation should describe the relation between indizes and texture coordinates.
Maybe my mesh generator cause the problem?! I’m using this indizes:
http://i.imgur.com/BDTaY.png
[java]
private static final ArrayList<Integer> TRIANGLE_INDIZES = Lists.newArrayList(2, 0, 1, 1, 3, 2);
[/java]
Please help again
Kind Regards
Andreas
Solved
Thanks pspeed and thetoucher … now I understand the concept
The order of the returned image coordinates must match with the TRIANGLE_INDIZES order!
Cya
Andreas
position buffer, normal buffer, texture buffer, tangent buffer, color buffer, etc… all relate one-to-one. position[5] matches normal[5] matches texture[5]. They all represent the vertex attributes.
The index buffer relates triangles to their vertexes (which includes the attributes for those vertexes).
I don’t know if that makes sense or is helpful at this point.