Hello. I want to draw a cube in openGL, which has its own texture on each face.

Here is such a working example of a cube in which one texture is used to fit all its faces:

public class Cube extends Abstract3DFigure { private FloatBuffer vertexBuffer; private FloatBuffer textureBuffer; private ByteBuffer indexBuffer; private int[] textures = new int[6]; private float vertices[] = { //Vertices according to faces -1.0f, -1.0f, 1.0f, //Vertex 0 1.0f, -1.0f, 1.0f, //v1 -1.0f, 1.0f, 1.0f, //v2 1.0f, 1.0f, 1.0f, //v3 1.0f, -1.0f, 1.0f, //... 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, -1.0f, 1.0f, -1.0f, -1.0f, -1.0f, -1.0f, -1.0f, 1.0f, 1.0f, -1.0f, -1.0f, 1.0f, -1.0f, -1.0f, -1.0f, -1.0f, -1.0f, -1.0f, 1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, -1.0f, -1.0f, -1.0f, 1.0f, -1.0f, -1.0f, -1.0f, -1.0f, 1.0f, 1.0f, -1.0f, 1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, -1.0f, 1.0f, -1.0f, 1.0f, 1.0f, -1.0f, }; private float texture[] = { //Mapping coordinates for the vertices 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, }; private byte indices[] = { //Faces definition 0, 1, 3, 0, 3, 2, //Face front 4, 5, 7, 4, 7, 6, //Face rightButtonPositiion 8, 9, 11, 8, 11, 10, //... 12, 13, 15, 12, 15, 14, 16, 17, 19, 16, 19, 18, 20, 21, 23, 20, 23, 22, }; public Cube(Context context) { ByteBuffer byteBuf = ByteBuffer.allocateDirect(vertices.length * 4); byteBuf.order(ByteOrder.nativeOrder()); vertexBuffer = byteBuf.asFloatBuffer(); vertexBuffer.put(vertices); vertexBuffer.position(0); byteBuf = ByteBuffer.allocateDirect(texture.length * 4); byteBuf.order(ByteOrder.nativeOrder()); textureBuffer = byteBuf.asFloatBuffer(); textureBuffer.put(texture); textureBuffer.position(0); indexBuffer = ByteBuffer.allocateDirect(indices.length); indexBuffer.put(indices); indexBuffer.position(0); } public void draw(GL10 gl) { gl.glPushMatrix(); gl.glTranslatef(0, 0, -10); //Move 5 units into the screen gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]); //Point to our buffers gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY); //Set the face rotation gl.glFrontFace(GL10.GL_CCW); //Enable the vertex and texture state gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer); gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, textureBuffer); //Draw the vertices as triangles, based on the Index Buffer information gl.glDrawElements(GL10.GL_TRIANGLES, indices.length, GL10.GL_UNSIGNED_BYTE, indexBuffer); gl.glPopMatrix(); } public void loadGLTexture(GL10 gl, Context context) { Bitmap bitmap = loadResurse(context, R.drawable.border); //Generate one texture pointer... gl.glGenTextures(1, textures, 0); //...and bind it to our array gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]); //Create Nearest Filtered Texture gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_NEAREST); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR); //Different possible texture parameters, eg GL10.GL_CLAMP_TO_EDGE gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S, GL10.GL_REPEAT); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T, GL10.GL_REPEAT); //Use the Android GLUtils to specify a two-dimensional texture image from our bitmap GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0); //Clean upButtonPositiion bitmap.recycle(); } private Bitmap loadResurse(Context context, int resourceId) { InputStream is = context.getResources().openRawResource(resourceId); Bitmap bitmap = null; try { //BitmapFactory is an Android graphics utility for images bitmap = BitmapFactory.decodeStream(is); } finally { //Always clear and close try { is.close(); } catch (IOException e) { } is = null; } return bitmap; } }

I would like to use different textures for different faces. In this code, I ship only one texture. Bitmap bitmap = loadResurse(context, R.drawable.border) ;
And you need 6 textures, I can get them in this way, but then how to pull them on different faces is not clear to me.

 Bitmap east = loadResurse(context, R.drawable.east); Bitmap north = loadResurse(context, R.drawable.north); Bitmap west = loadResurse(context, R.drawable.west); Bitmap south = loadResurse(context, R.drawable.south); Bitmap up = loadResurse(context, R.drawable.up); Bitmap down = loadResurse(context, R.drawable.down);

How can i do this ?

    1 answer 1

    Hello! As an option, along with an array of positions and texture coordinates, you can pass another attribute - this is a float flag, which texture to use. Then check the value of the flag in the shader: for example, if flag == 0 - use the first texture, if flag == 1, then the second texture, etc.