How to implement a Matrix Palette
/*
* Copyright (C) 2009 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package app.test;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.CharBuffer;
import java.nio.FloatBuffer;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL;
import javax.microedition.khronos.opengles.GL10;
import javax.microedition.khronos.opengles.GL11;
import javax.microedition.khronos.opengles.GL11Ext;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.opengl.GLSurfaceView;
import android.opengl.GLU;
import android.opengl.GLUtils;
import android.os.Bundle;
import android.os.SystemClock;
class MatrixPaletteRenderer implements GLSurfaceView.Renderer {
private Context mContext;
private Grid mGrid;
private int mTextureID;
/**
* A grid is a topologically rectangular array of vertices.
*
* This grid class is customized for the vertex data required for this
* example.
*
* The vertex and index data are held in VBO objects because on most GPUs
* VBO objects are the fastest way of rendering static vertex and index
* data.
*
*/
private static class Grid {
// Size of vertex data elements in bytes:
final static int FLOAT_SIZE = 4;
final static int CHAR_SIZE = 2;
// Vertex structure:
// float x, y, z;
// float u, v;
// float weight0, weight1;
// byte palette0, palette1, pad0, pad1;
final static int VERTEX_SIZE = 8 * FLOAT_SIZE;
final static int VERTEX_TEXTURE_BUFFER_INDEX_OFFSET = 3;
final static int VERTEX_WEIGHT_BUFFER_INDEX_OFFSET = 5;
final static int VERTEX_PALETTE_INDEX_OFFSET = 7 * FLOAT_SIZE;
private int mVertexBufferObjectId;
private int mElementBufferObjectId;
// These buffers are used to hold the vertex and index data while
// constructing the grid. Once createBufferObjects() is called
// the buffers are nulled out to save memory.
private ByteBuffer mVertexByteBuffer;
private FloatBuffer mVertexBuffer;
private CharBuffer mIndexBuffer;
private int mW;
private int mH;
private int mIndexCount;
public Grid(int w, int h) {
if (w < 0 || w >= 65536) {
throw new IllegalArgumentException("w");
}
if (h < 0 || h >= 65536) {
throw new IllegalArgumentException("h");
}
if (w * h >= 65536) {
throw new IllegalArgumentException("w * h >= 65536");
}
mW = w;
mH = h;
int size = w * h;
mVertexByteBuffer = ByteBuffer.allocateDirect(VERTEX_SIZE * size)
.order(ByteOrder.nativeOrder());
mVertexBuffer = mVertexByteBuffer.asFloatBuffer();
int quadW = mW - 1;
int quadH = mH - 1;
int quadCount = quadW * quadH;
int indexCount = quadCount * 6;
mIndexCount = indexCount;
mIndexBuffer = ByteBuffer.allocateDirect(CHAR_SIZE * indexCount)
.order(ByteOrder.nativeOrder()).asCharBuffer();
/*
* Initialize triangle list mesh.
*
* [0]-----[ 1] ... | / | | / | | / | [w]-----[w+1] ... | |
*/
{
int i = 0;
for (int y = 0; y < quadH; y++) {
for (int x = 0; x < quadW; x++) {
char a = (char) (y * mW + x);
char b = (char) (y * mW + x + 1);
char c = (char) ((y + 1) * mW + x);
char d = (char) ((y + 1) * mW + x + 1);
mIndexBuffer.put(i++, a);
mIndexBuffer.put(i++, c);
mIndexBuffer.put(i++, b);
mIndexBuffer.put(i++, b);
mIndexBuffer.put(i++, c);
mIndexBuffer.put(i++, d);
}
}
}
}
public void set(int i, int j, float x, float y, float z, float u,
float v, float w0, float w1, int p0, int p1) {
if (i < 0 || i >= mW) {
throw new IllegalArgumentException("i");
}
if (j < 0 || j >= mH) {
throw new IllegalArgumentException("j");
}
if (w0 + w1 != 1.0f) {
throw new IllegalArgumentException(
"Weights must add up to 1.0f");
}
int index = mW * j + i;
mVertexBuffer.position(index * VERTEX_SIZE / FLOAT_SIZE);
mVertexBuffer.put(x);
mVertexBuffer.put(y);
mVertexBuffer.put(z);
mVertexBuffer.put(u);
mVertexBuffer.put(v);
mVertexBuffer.put(w0);
mVertexBuffer.put(w1);
mVertexByteBuffer.position(index * VERTEX_SIZE
+ VERTEX_PALETTE_INDEX_OFFSET);
mVertexByteBuffer.put((byte) p0);
mVertexByteBuffer.put((byte) p1);
}
public void createBufferObjects(GL gl) {
// Generate a the vertex and element buffer IDs
int[] vboIds = new int[2];
GL11 gl11 = (GL11) gl;
gl11.glGenBuffers(2, vboIds, 0);
mVertexBufferObjectId = vboIds[0];
mElementBufferObjectId = vboIds[1];
// Upload the vertex data
gl11.glBindBuffer(GL11.GL_ARRAY_BUFFER, mVertexBufferObjectId);
mVertexByteBuffer.position(0);
gl11.glBufferData(GL11.GL_ARRAY_BUFFER,
mVertexByteBuffer.capacity(), mVertexByteBuffer,
GL11.GL_STATIC_DRAW);
gl11.glBindBuffer(GL11.GL_ELEMENT_ARRAY_BUFFER,
mElementBufferObjectId);
mIndexBuffer.position(0);
gl11.glBufferData(GL11.GL_ELEMENT_ARRAY_BUFFER,
mIndexBuffer.capacity() * CHAR_SIZE, mIndexBuffer,
GL11.GL_STATIC_DRAW);
// We don't need the in-memory data any more
mVertexBuffer = null;
mVertexByteBuffer = null;
mIndexBuffer = null;
}
public void draw(GL10 gl) {
GL11 gl11 = (GL11) gl;
GL11Ext gl11Ext = (GL11Ext) gl;
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
gl11.glBindBuffer(GL11.GL_ARRAY_BUFFER, mVertexBufferObjectId);
gl11.glVertexPointer(3, GL10.GL_FLOAT, VERTEX_SIZE, 0);
gl11.glTexCoordPointer(2, GL10.GL_FLOAT, VERTEX_SIZE,
VERTEX_TEXTURE_BUFFER_INDEX_OFFSET * FLOAT_SIZE);
gl.glEnableClientState(GL11Ext.GL_MATRIX_INDEX_ARRAY_OES);
gl.glEnableClientState(GL11Ext.GL_WEIGHT_ARRAY_OES);
gl11Ext.glWeightPointerOES(2, GL10.GL_FLOAT, VERTEX_SIZE,
VERTEX_WEIGHT_BUFFER_INDEX_OFFSET * FLOAT_SIZE);
gl11Ext.glMatrixIndexPointerOES(2, GL10.GL_UNSIGNED_BYTE,
VERTEX_SIZE, VERTEX_PALETTE_INDEX_OFFSET);
gl11.glBindBuffer(GL11.GL_ELEMENT_ARRAY_BUFFER,
mElementBufferObjectId);
gl11.glDrawElements(GL10.GL_TRIANGLES, mIndexCount,
GL10.GL_UNSIGNED_SHORT, 0);
gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
gl.glDisableClientState(GL11Ext.GL_MATRIX_INDEX_ARRAY_OES);
gl.glDisableClientState(GL11Ext.GL_WEIGHT_ARRAY_OES);
gl11.glBindBuffer(GL11.GL_ARRAY_BUFFER, 0);
gl11.glBindBuffer(GL11.GL_ELEMENT_ARRAY_BUFFER, 0);
}
}
public MatrixPaletteRenderer(Context context) {
mContext = context;
}
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
/*
* By default, OpenGL enables features that improve quality but reduce
* performance. One might want to tweak that especially on software
* renderer.
*/
gl.glDisable(GL10.GL_DITHER);
/*
* Some one-time OpenGL initialization can be made here probably based
* on features of this particular context
*/
gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_FASTEST);
gl.glClearColor(.5f, .5f, .5f, 1);
gl.glShadeModel(GL10.GL_SMOOTH);
gl.glEnable(GL10.GL_DEPTH_TEST);
gl.glEnable(GL10.GL_TEXTURE_2D);
/*
* Create our texture. This has to be done each time the surface is
* created.
*/
int[] textures = new int[1];
gl.glGenTextures(1, textures, 0);
mTextureID = textures[0];
gl.glBindTexture(GL10.GL_TEXTURE_2D, mTextureID);
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);
gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S,
GL10.GL_CLAMP_TO_EDGE);
gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T,
GL10.GL_CLAMP_TO_EDGE);
gl.glTexEnvf(GL10.GL_TEXTURE_ENV, GL10.GL_TEXTURE_ENV_MODE,
GL10.GL_REPLACE);
InputStream is = mContext.getResources().openRawResource(R.raw.robot);
Bitmap bitmap;
try {
bitmap = BitmapFactory.decodeStream(is);
} finally {
try {
is.close();
} catch (IOException e) {
// Ignore.
}
}
GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0);
bitmap.recycle();
mGrid = generateWeightedGrid(gl);
}
public void onDrawFrame(GL10 gl) {
/*
* By default, OpenGL enables features that improve quality but reduce
* performance. One might want to tweak that especially on software
* renderer.
*/
gl.glDisable(GL10.GL_DITHER);
gl.glTexEnvx(GL10.GL_TEXTURE_ENV, GL10.GL_TEXTURE_ENV_MODE,
GL10.GL_MODULATE);
/*
* Usually, the first thing one might want to do is to clear the screen.
* The most efficient way of doing this is to use glClear().
*/
gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
gl.glEnable(GL10.GL_DEPTH_TEST);
gl.glEnable(GL10.GL_CULL_FACE);
/*
* Now we're ready to draw some 3D objects
*/
gl.glMatrixMode(GL10.GL_MODELVIEW);
gl.glLoadIdentity();
GLU.gluLookAt(gl, 0, 0, -5, 0f, 0f, 0f, 0f, 1.0f, 0.0f);
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
gl.glActiveTexture(GL10.GL_TEXTURE0);
gl.glBindTexture(GL10.GL_TEXTURE_2D, mTextureID);
gl.glTexParameterx(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S,
GL10.GL_REPEAT);
gl.glTexParameterx(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T,
GL10.GL_REPEAT);
long time = SystemClock.uptimeMillis() % 4000L;
// Rock back and forth
double animationUnit = ((double) time) / 4000;
float unitAngle = (float) Math.cos(animationUnit * 2 * Math.PI);
float angle = unitAngle * 135f;
gl.glEnable(GL11Ext.GL_MATRIX_PALETTE_OES);
gl.glMatrixMode(GL11Ext.GL_MATRIX_PALETTE_OES);
GL11Ext gl11Ext = (GL11Ext) gl;
// matrix 0: no transformation
gl11Ext.glCurrentPaletteMatrixOES(0);
gl11Ext.glLoadPaletteFromModelViewMatrixOES();
// matrix 1: rotate by "angle"
gl.glRotatef(angle, 0, 0, 1.0f);
gl11Ext.glCurrentPaletteMatrixOES(1);
gl11Ext.glLoadPaletteFromModelViewMatrixOES();
mGrid.draw(gl);
gl.glDisable(GL11Ext.GL_MATRIX_PALETTE_OES);
}
public void onSurfaceChanged(GL10 gl, int w, int h) {
gl.glViewport(0, 0, w, h);
/*
* Set our projection matrix. This doesn't have to be done each time we
* draw, but usually a new projection needs to be set when the viewport
* is resized.
*/
float ratio = (float) w / h;
gl.glMatrixMode(GL10.GL_PROJECTION);
gl.glLoadIdentity();
gl.glFrustumf(-ratio, ratio, -1, 1, 3, 7);
}
private Grid generateWeightedGrid(GL gl) {
final int uSteps = 20;
final int vSteps = 20;
float radius = 0.25f;
float height = 2.0f;
Grid grid = new Grid(uSteps + 1, vSteps + 1);
for (int j = 0; j <= vSteps; j++) {
for (int i = 0; i <= uSteps; i++) {
double angle = Math.PI * 2 * i / uSteps;
float x = radius * (float) Math.cos(angle);
float y = height * ((float) j / vSteps - 0.5f);
float z = radius * (float) Math.sin(angle);
float u = -4.0f * (float) i / uSteps;
float v = -4.0f * (float) j / vSteps;
float w0 = (float) j / vSteps;
float w1 = 1.0f - w0;
grid.set(i, j, x, y, z, u, v, w0, w1, 0, 1);
}
}
grid.createBufferObjects(gl);
return grid;
}
}
/**
* This sample shows how to implement a Matrix Palette
*/
public class MatrixPaletteActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mGLSurfaceView = new GLSurfaceView(this);
mGLSurfaceView.setRenderer(new MatrixPaletteRenderer(this));
setContentView(mGLSurfaceView);
}
@Override
protected void onResume() {
// Ideally a game should implement onResume() and onPause()
// to take appropriate action when the activity looses focus
super.onResume();
mGLSurfaceView.onResume();
}
@Override
protected void onPause() {
// Ideally a game should implement onResume() and onPause()
// to take appropriate action when the activity looses focus
super.onPause();
mGLSurfaceView.onPause();
}
private GLSurfaceView mGLSurfaceView;
}
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