Android UI How to - Draw a Pyramid with Texture in OpenGL

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The following code shows how to Draw a Pyramid with Texture in OpenGL.

Example

Main Activity Java code

package com.java2s.myapplication4.app;
/*from  w w  w .j av a2s . c o m*/
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.opengl.GLSurfaceView;
import android.opengl.GLSurfaceView.Renderer;
import android.opengl.GLU;
import android.opengl.GLUtils;
import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;

import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;

public class MainActivity extends Activity {

    private GLSurfaceView glView;
    private TexturedPyramid pyramid;
    private Bitmap texture;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
        glView = new GLSurfaceView(this);
        glView.setRenderer(new MyOpenGLRenderer());
        setContentView(glView);
    }

    class MyOpenGLRenderer implements Renderer {

        @Override
        public void onSurfaceChanged(GL10 gl, int width, int height) {
            gl.glViewport(0, 0, width, height);
            gl.glMatrixMode(GL10.GL_PROJECTION);
            gl.glLoadIdentity();
            GLU.gluPerspective(gl, 45.0f, (float) width / (float) height, 0.1f, 100.0f);
            gl.glMatrixMode(GL10.GL_MODELVIEW);
            gl.glLoadIdentity();
        }

        @Override
        public void onSurfaceCreated(GL10 gl, EGLConfig config) {
            texture = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
            int textureIds[] = new int[1];
            gl.glGenTextures(1, textureIds, 0);
            gl.glBindTexture(GL10.GL_TEXTURE_2D, textureIds[0]);
            GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, texture, 0);
            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_NEAREST);
            gl.glBindTexture(GL10.GL_TEXTURE_2D, 0);
            texture.recycle();
            pyramid = new TexturedPyramid(textureIds[0]);
        }

        @Override
        public void onDrawFrame(GL10 gl) {
            gl.glClearColor(0.0f, 0.0f, 0.0f, 1f);
            gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
            gl.glLoadIdentity();
            gl.glTranslatef(0.0f, 0.0f, -5.0f);
            pyramid.draw(gl);
        }
    }
}

class TexturedPyramid {

    private int textureId;
    private FloatBuffer vertexBuffer;
    private static final int VERTEX_SIZE = (3 + 2) * 4;
    private float vertices[] = {

            0.0f, 1.0f, 0.0f, 0.5f, 0.0f, // V1 + mapping
            -1.0f, 0.0f, 0.0f, 0.0f, 1.0f, // V2
            0.0f, 0.0f, -1.0f, 1.0f, 1.0f, // V3

            0.0f, 1.0f, 0.0f, 0.5f, 0.0f, // V1
            0.0f, 0.0f, -1.0f, 0.0f, 1.0f, // V3
            1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // V4

            0.0f, 1.0f, 0.0f, 0.5f, 0.0f, // V1
            1.0f, 0.0f, 0.0f, 0.0f, 1.0f, // V4
            -1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // V2

    };

    private float rotation = 0.1f;

    public TexturedPyramid(int textureId) {
        ByteBuffer byteBuffer = ByteBuffer.allocateDirect(TexturedPyramid.VERTEX_SIZE * 3 * 3);
        byteBuffer.order(ByteOrder.nativeOrder());
        vertexBuffer = byteBuffer.asFloatBuffer();
        vertexBuffer.put(vertices);
        vertexBuffer.flip();
        this.textureId = textureId;
    }

    public void draw(GL10 gl) {
        rotation += 1.0f;
        gl.glRotatef(rotation, 1f, 1f, 1f);

        gl.glEnable(GL10.GL_TEXTURE_2D);
        gl.glBindTexture(GL10.GL_TEXTURE_2D, textureId);

        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);

        vertexBuffer.position(0);
        gl.glVertexPointer(3, GL10.GL_FLOAT, TexturedPyramid.VERTEX_SIZE, vertexBuffer);
        vertexBuffer.position(3);
        gl.glTexCoordPointer(2, GL10.GL_FLOAT, TexturedPyramid.VERTEX_SIZE, vertexBuffer);

        gl.glDrawArrays(GL10.GL_TRIANGLES, 0, 3 * 3);
        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
    }
}

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