问题
I am trying to display a single texture on a quad. I had a working VertexObject, which drew a square(or any geometric object) fine. Now I tried expanding it to handle textures too, and the textures doesn't work. I only see the quad in one solid color.
The coordinate data is in an arrayList:
/*the vertices' coordinates*/
public int coordCount = 0;
/*float array of 3(x,y,z)*/
public ArrayList<Float> coordList = new ArrayList<Float>(coordCount);
/*the coordinates' indexes(if used)*/
/*maximum limit:32767*/
private int orderCount = 0;
private ArrayList<Short> orderList = new ArrayList<Short>(orderCount);
/*textures*/
public boolean textured;
private boolean textureIsReady;
private ArrayList<Float> textureList = new ArrayList<Float>(coordCount);
private Bitmap bitmap; //the image to be displayed
private int textures[]; //the textures' ids
The buffers are initialized in the following function:
/*Drawing is based on the buffers*/
public void refreshBuffers(){
/*Coordinates' List*/
float coords[] = new float[coordList.size()];
for(int i=0;i<coordList.size();i++){
coords[i]= coordList.get(i);
}
// initialize vertex byte buffer for shape coordinates
ByteBuffer bb = ByteBuffer.allocateDirect(
// (number of coordinate values * 4 bytes per float)
coords.length * 4);
// use the device hardware's native byte order
bb.order(ByteOrder.nativeOrder());
// create a floating point buffer from the ByteBuffer
vertexBuffer = bb.asFloatBuffer();
// add the coordinates to the FloatBuffer
vertexBuffer.put(coords);
// set the buffer to read the first coordinate
vertexBuffer.position(0);
/*Index List*/
short order[] = new short[(short)orderList.size()];
for(int i=0;i<order.length;i++){
order[i] = (short) orderList.get(i);
}
// initialize byte buffer for the draw list
ByteBuffer dlb = ByteBuffer.allocateDirect(
// (# of coordinate values * 2 bytes per short)
order.length * 2);
dlb.order(ByteOrder.nativeOrder());
orderBuffer = dlb.asShortBuffer();
orderBuffer.put(order);
orderBuffer.position(0);
/*texture list*/
if(textured){
float textureCoords[] = new float[textureList.size()];
for(int i=0;i<textureList.size();i++){
textureCoords[i] = textureList.get(i);
}
ByteBuffer byteBuf = ByteBuffer.allocateDirect(textureCoords.length * 4);
byteBuf.order(ByteOrder.nativeOrder());
textureBuffer = byteBuf.asFloatBuffer();
textureBuffer.put(textureCoords);
textureBuffer.position(0);
}
}
I load the image into the object with the following code:
public void initTexture(GL10 gl, Bitmap inBitmap){
bitmap = inBitmap;
loadTexture(gl);
textureIsReady = true;
}
/*http://www.jayway.com/2010/12/30/opengl-es-tutorial-for-android-part-vi-textures/*/
public void loadTexture(GL10 gl){
gl.glGenTextures(1, textures, 0);
gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]);
gl.glTexParameterx(GL10.GL_TEXTURE_2D,
GL10.GL_TEXTURE_MAG_FILTER,
GL10.GL_LINEAR);
gl.glTexParameterx(GL10.GL_TEXTURE_2D,
GL10.GL_TEXTURE_MIN_FILTER,
GL10.GL_LINEAR);
gl.glTexParameterx(GL10.GL_TEXTURE_2D,
GL10.GL_TEXTURE_WRAP_S,
GL10.GL_CLAMP_TO_EDGE);
gl.glTexParameterx(GL10.GL_TEXTURE_2D,
GL10.GL_TEXTURE_WRAP_T,
GL10.GL_CLAMP_TO_EDGE);
/*bind bitmap to texture*/
GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0);
}
And the drawing happens based on this code:
public void draw(GL10 gl){
if(textured && textureIsReady){
gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]);
//loadTexture(gl);
gl.glEnable(GL10.GL_TEXTURE_2D);
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
gl.glVertexPointer(3, GL10.GL_FLOAT, 0,
vertexBuffer);
gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0,
textureBuffer);
}else{
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
gl.glColor4f(color[0], color[1], color[2], color[3]);
gl.glVertexPointer(3, GL10.GL_FLOAT, 0,
vertexBuffer);
}
if(!indexed)gl.glDrawArrays(drawMode, 0, coordCount);
else gl.glDrawElements(drawMode, orderCount, GL10.GL_UNSIGNED_SHORT, orderBuffer);
if(textured && textureIsReady){
gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
gl.glDisable(GL10.GL_TEXTURE_2D);
}else{
gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
}
}
The initialization is as follows:
pic = new VertexObject();
pic.indexed = true;
pic.textured = true;
pic.initTexture(gl,MainActivity.bp);
pic.color[0] = 0.0f;
pic.color[1] = 0.0f;
pic.color[2] = 0.0f;
float inputVertex[] = {2.0f,2.0f,0.0f};
float inputTexture[] = {0.0f,0.0f};
pic.addTexturedVertex(inputVertex,inputTexture);
inputVertex[0] = 2.0f;
inputVertex[1] = 8.0f;
inputTexture[0] = 0.0f;
inputTexture[0] = 1.0f;
pic.addTexturedVertex(inputVertex,inputTexture);
inputVertex[0] = 8.0f;
inputVertex[1] = 8.0f;
inputTexture[0] = 1.0f;
inputTexture[0] = 1.0f;
pic.addTexturedVertex(inputVertex,inputTexture);
inputVertex[0] = 8.0f;
inputVertex[1] = 2.0f;
inputTexture[0] = 1.0f;
inputTexture[0] = 0.0f;
pic.addTexturedVertex(inputVertex,inputTexture);
pic.addIndex((short)0);
pic.addIndex((short)1);
pic.addIndex((short)2);
pic.addIndex((short)0);
pic.addIndex((short)2);
pic.addIndex((short)3);
The coordinates are just simply added to the arrayList, and then I refresh the buffers. The bitmap is valid, because it is showing up on an imageView. The image is a png file with the size of 128x128 in the drawable folder. For what I gathered the image is getting to the vertexObject, but something isn't right with the texture mapping. Any pointers on what am I doing wrong?
回答1:
Okay, I got it!
I downloaded a working example from the internet and rewrote it, to resemble the object(presented above) step by step. I observed if it works on every step. Turns out, the problem isn't in the graphical part, because the object worked in another context with different coordinates.
Long story short:
I got the texture UV mapping wrong! That's why I got the solid color, the texture was loaded, but the UV mapping wasn't correct.
Short story long:
At the lines
inputVertex[0] = 2.0f;
inputVertex[1] = 8.0f;
inputTexture[0] = 0.0f;
inputTexture[0] = 1.0f;
The indexing was wrong as only the first element of inputTexture was updated only. There might have been some additional errors regarding the sizes of the different array describing the vertex coordinates, but rewriting on the linked example fixed the problem, and it produced a mroe concise code.
来源：https://stackoverflow.com/questions/14158617/android-texture-only-showing-solid-color