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Thread: OpenGL Texture won't draw

  1. #1

    Default OpenGL Texture won't draw

    I have followed a tutorial on how to display an image in OpenGL, and I first had to make a square and then texture it. I have tried
    gl.glColor4f(0f,0f,0f,1f);
    and that works, I can see the square. But then when I try to texture it, the screen just stays white. What did I do wrong?

    Here is the screen with the
    gl.glColor4f(0f,0f,0f,1f);
    :

    lYaCq.jpg

    If I apply the texture (using the custom Texture class that the tutorial suggested), the screen is completely white.

    Here is my code:

    Square.java:

    package com.nivangerow.android.reference;
     
    import java.nio.ByteBuffer;
    import java.nio.ByteOrder;
    import java.nio.FloatBuffer;
    import java.nio.ShortBuffer;
     
    import javax.microedition.khronos.opengles.GL10;
     
    import android.content.Context;
     
    public class Square
    {
    	final int VERTEX_SIZE = (2+2) *4;
    	FloatBuffer vertices;
    	ShortBuffer indices;
     
    	Texture texture;
     
    	GL10 gl;
    	Context c;
     
    	public Square(GL10 gl, Context context)
    	{
    		this.gl = gl;
    		this.c = context;
     
    		ByteBuffer byteBuffer = ByteBuffer.allocateDirect(VERTEX_SIZE * 4);
    		byteBuffer.order(ByteOrder.nativeOrder());
    		vertices = byteBuffer.asFloatBuffer();
    		vertices.put(new float[]{
    			10.0f, 10.0f, 0.0f, 0.0f, //bl	
    			160.0f, 10.0f, 1.0f, 0.0f, //br	
    			160.0f, 160.0f, 1.0f, 1.0f, //tr	
    			10.0f, 160.0f, 1.0f, 0.0f, //tl	
    		});
    		vertices.flip();
     
    		vertices.position(0);
     
    		byteBuffer = ByteBuffer.allocateDirect(VERTEX_SIZE * 4);
    		byteBuffer.order(ByteOrder.nativeOrder());
    		indices = byteBuffer.asShortBuffer();
    		indices.put(new short[]{
    			0, 1, 2, 2, 3, 0
    		});
    		indices.flip();
     
    		indices.position(0);
     
    		texture = new Texture("image/picture.png", c, gl);
    	}
     
    	public void draw()
    	{
    		gl.glEnable(GL10.GL_TEXTURE_2D);
    		texture.bind();
    		//gl.glColor4f(0f, 0f, 0f, 1f);
     
    		gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
    		gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
     
    		vertices.position(0);
    		gl.glVertexPointer(2, GL10.GL_FLOAT, VERTEX_SIZE, vertices);
    		vertices.position(2);
    		gl.glTexCoordPointer(2, GL10.GL_FLOAT, VERTEX_SIZE, vertices);
     
    		gl.glDrawElements(GL10.GL_TRIANGLES, 6, GL10.GL_UNSIGNED_SHORT, indices);
    	}
    }

    Texture.java

    package com.nivangerow.android.reference;
     
    import java.io.InputStream;
     
    import javax.microedition.khronos.opengles.GL10;
     
    import android.content.Context;
    import android.content.res.AssetManager;
    import android.graphics.Bitmap;
    import android.graphics.BitmapFactory;
    import android.opengl.GLUtils;
     
    public class Texture {
     
    	String texturePath;
    	Context context;
    	GL10 gl;
     
    	int textureId;
    	int minFilter;
    	int magFilter;
    	Bitmap texture;
     
    	public Texture(String texturePath, Context context, GL10 gl)
    	{
    		this.gl = gl;
    		this.texturePath = texturePath;
    		this.context = context;
    	}
     
    	public void load()
    	{
    		try{
    			AssetManager assetManager = context.getAssets();
    			InputStream is = assetManager.open(texturePath);
    			texture = BitmapFactory.decodeStream(is);
    			gl.glBindTexture(GL10.GL_TEXTURE_2D, textureId);
    			GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, texture, 0);
    			setFilters(GL10.GL_NEAREST, GL10.GL_NEAREST);
    			gl.glBindTexture(GL10.GL_TEXTURE_2D, 0);
    		}catch(Exception e)
    		{
    			e.printStackTrace();
    		}
    	}
     
    	public void reload()
    	{
    		load();
    		bind();
    		setFilters(minFilter, magFilter);
    		gl.glBindTexture(GL10.GL_TEXTURE_2D, 0);
    	}
     
    	public void setFilters(int minFilter, int magFilter)
    	{
    		this.minFilter = minFilter;
    		this.magFilter = magFilter;
    		gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, minFilter);
    		gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, magFilter);
    	}
     
    	public void bind()
    	{
    		gl.glBindTexture(GL10.GL_TEXTURE_2D, textureId);
    	}
     
    	public void dispose()
    	{
    		gl.glBindTexture(GL10.GL_TEXTURE_2D, textureId);
    		int[] textureIds = {textureId};
    		gl.glDeleteTextures(1, textureIds, 0);
    	}
     
    }

    OpenGLRenderer.java

    package com.nivangerow.android.reference;
     
    import java.util.Random;
     
    import javax.microedition.khronos.egl.EGLConfig;
    import javax.microedition.khronos.opengles.GL10;
     
    import android.content.Context;
    import android.opengl.GLSurfaceView.Renderer;
     
    public class OpenGLRenderer implements Renderer 
    {
    	Random rand = new Random();
    	int mWidth = 0;
    	int mHeight = 0;
     
    	Context c;
     
    	Square square;
     
    	public OpenGLRenderer(Context c)
    	{
    		this.c = c;
    	}
     
    	@Override
    	public void onDrawFrame(GL10 gl) 
    	{
    		gl.glClearColor(1, 1, 1, 1);
    		gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
    		gl.glViewport(0, 0, mWidth, mHeight);
    		gl.glMatrixMode(GL10.GL_PROJECTION);
    		gl.glLoadIdentity();
    		gl.glOrthof(0, mWidth, 0, mHeight, 1, -1);
     
    		if(square != null)square.draw();
    	}
     
    	@Override
    	public void onSurfaceChanged(GL10 gl, int width, int height) 
    	{
    		mWidth = width;
    		mHeight = height;
    	}
     
    	@Override
    	public void onSurfaceCreated(GL10 gl, EGLConfig config) 
    	{
    		square = new Square(gl, c);
    	}
     
    }

    Thanks in advance.


  2. #2

    Default Re: OpenGL Texture won't draw

    Im stupid, I forgot to call the load() method in the texture object.
    Last edited by nivangerow; November 26th, 2011 at 05:10 AM.

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