Tex coordinates, texturing a simple cube

Troubleshooting graphics
1

Hi, i have some problems with texturing a simple cube :wink:







i found a topic in the forum (http://hub.jmonkeyengine.org/groups/graphics/forum/topic/texture-mapping-problems-with-tex-coordinates/) but it doesn’t solve my problem.



I use 24 vertexes for my cube, here is my code:



[java]//Build Cube



//front face

float [] frontvert = {0,0,0, 1,0,0, 0,1,0, 1,1,0};



//back face

float [] backvert = {0,0,-1, 1,0,-1, 0,1,-1, 1,1,-1};



//left face

float [] leftvert = {0,0,-1, 0,0,0, 0,1,-1, 0,1,0};



//right face

float [] rightvert = {1,0,0, 1,0,-1, 1,1,0, 1,1,-1};



//top face

float [] topvert = {0,1,0, 1,1,0, 0,1,-1, 1,1,-1};



//bottom face

float [] bottomvert = {0,0,0, 1,0,0, 0,0,-1, 1,0,-1};



// Indexes. We define the order in which mesh should be constructed

int [] indexes = {1,3,2, 2,0,1, 6,7,5, 5,4,6, 5,7,3, 3,1,5, 2,6,4, 4,0,2, 3,7,6, 6,2,3, 4,5,1, 1,0,4};



if (this.getBuffer(Type.Position) == null) {



FloatBuffer bufferPos = BufferUtils.createFloatBuffer(243);

this.setBuffer(Type.Position, 3, bufferPos);



FloatBuffer bufferTex = BufferUtils.createFloatBuffer(243);

this.setBuffer(Type.TexCoord, 3, bufferTex);



IntBuffer bufferInd = BufferUtils.createIntBuffer(36);

this.setBuffer(Type.Index, 1, bufferInd);



}

FloatBuffer buffer = (FloatBuffer) this.getBuffer(Type.Position).getData();

buffer.put(frontvert);

buffer.put(backvert);

buffer.put(leftvert);

buffer.put(rightvert);

buffer.put(topvert);

buffer.put(bottomvert);



FloatBuffer buffer2 = (FloatBuffer) this.getBuffer(Type.TexCoord).getData();

buffer2.put(frontvert);

buffer2.put(backvert);

buffer2.put(leftvert);

buffer2.put(rightvert);

buffer2.put(topvert);

buffer2.put(bottomvert);



IntBuffer buffer3 = (IntBuffer) this.getBuffer(Type.Index).getData();

buffer3.put(indexes);



this.updateBound();

[/java]

2

Look at com.jme3.scene.shape.Box for an example on how to do it.

3

Since you are using negative texture coordinates then you will need to make sure that your texture has wrapping enabled. Or fix the texture coordinates to be 0 to 1.

4

bufferTex and buffer2 seem wrong.

a) bufferTex : u-v coordinates are only 2 not 3.

[java]

this.setBuffer(Type.TexCoord, 2, bufferTex);

[/java]



b) buffer2 : i would copy paste the same u-v coordinates (the ones of the front face)



[java]

float left = 0;

float right = 1;

float top = 1;

float bot = 0;

float[] frontUV = { left, top, right, top, right, bot, left, bot };

buffer2.put(frontUV );

buffer2.put(frontUV );

buffer2.put(frontUV );

buffer2.put(frontUV );

buffer2.put(frontUV );

buffer2.put(frontUV );

[/java]



i don’t know if that helps

5

^^^ Yes, of course. That’s true also. For some of your faces the texture coordinates will have the same x values and for some the same y.



…good catch, @tralala

6

ok i have it^^



my problem were the wrong buffertex (thx tralala) and i have took only indexes from 0…7 but I need 0…23



thx for your help :slight_smile:



an another question, how can I delete some floats from the buffer to delete vertices. I can add them with buffer.put but it seems there is no method to delete them, maybe I have to set a new buffer?

7

i get the buffer, and resent all data (updated).

a) you cannot delete things from a buffer. You can however replace them with something else.



here is my example from my sprite lib:



[java]

private void updatePositions()

{

if (positionBufferChanged)

{

VertexBuffer pvb = mesh.getBuffer(VertexBuffer.Type.Position);

FloatBuffer positions = (FloatBuffer) pvb.getData();

positions.rewind();

for (int i = 0; i < sprites.size(); i++)

{

Vector3f position = sprites.get(i).getPosition();

positions.put(position.x).put(position.y).put(position.z);

}

positions.flip();

pvb.updateData(positions);

}

}

[/java]