Develop Reference

android opengl es 2 display after several rotate error

I am trying to draw lines connected to each other. Let's say they are creating a
rectangle. At each corner also I have points. When I have tested code in my
Samsung Galaxy Note 4 after several rotations, using touch, all rectangle ended up
with a single point at the center. I could not figure out why this was happening.
Code works fine in emulator. Also I am storing line and point data as array list
in my code. These array lists are used to create line and point object classes to
render.
public class GLRender implements GLSurfaceView.Renderer {
private final float[] mMVPMatrix = new float[16];
private final float[] mProjectionMatrix = new float[16];
private final float[] mViewMatrix = new float[16];
private float[] mRotationMatrix = new float[16];
private float[] mVRMatrix = new float[16];
private static ArrayList<Line> DrLine = new ArrayList<Line>();
private static ArrayList<Point> DrPoint = new ArrayList<Point>();
private float ratio;
private float Joint1;
private float Joint2;
private float x1, y1, z1, x2, y2, z2;
private float px, py, pz, ps;
private float[] nearN = new float[4];
private static ArrayList<ArrayList<String>> LineArray = new ArrayList<ArrayList<String>>();
private ArrayList<String> L = new ArrayList<String>();
private ArrayList<String> P = new ArrayList<String>();
private static ArrayList<ArrayList<String>> PointArray = new ArrayList<ArrayList<String>>();
private static ArrayList<String> EmptyLine = new ArrayList<String>();
private static ArrayList<String> EmptyPoint = new ArrayList<String>();
private static ArrayList<ArrayList<ArrayList<String>>> UndoL = new ArrayList<ArrayList<ArrayList<String>>>();
private static ArrayList<ArrayList<ArrayList<String>>> UndoP = new ArrayList<ArrayList<ArrayList<String>>>();
public GLRender(Activity activity) {
}
public void onSurfaceCreated(GL10 unused, EGLConfig config) {
// Set the background frame color
//GLES20.glClearColor(0.53f, 0.53f, 0.53f, 1.0f);
GLES20.glClearColor(0.474f, 0.537f, 0.078f, 1.0f);
}
public void onDrawFrame(GL10 unused) {
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT);
Drawer();
Line XLine = new Line();
XLine.SetVerts(0.0f, 0.0f, 0.0f, 1.0f / 10, 0.0f, 0.0f);
XLine.SetColor(1.0f, 0.0f, 0.0f, 1.0f);
Line YLine = new Line();
YLine.SetVerts(0.0f, 0.0f, 0.0f, 0.0f, 1.0f / 10, 0.0f);
YLine.SetColor(0.0f, 1.0f, 0.0f, 1.0f);
Line ZLine = new Line();
ZLine.SetVerts(0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f / 10);
ZLine.SetColor(0.0f, 0.0f, 1.0f, 1.0f);
Matrix.setIdentityM(mViewMatrix, 0);
Matrix.setLookAtM(mViewMatrix, 0, 0, 0, 1.0f , 0f, 0f, 0f, 0f, 1.0f, 0.0f);
Matrix.setIdentityM(mRotationMatrix, 0);
Matrix.rotateM(mRotationMatrix, 0, mXAngle, 0, 1f, 0);
Matrix.rotateM(mRotationMatrix, 0, mYAngle, 1f, 0, 0);
Matrix.setIdentityM(mVRMatrix, 0);
Matrix.multiplyMM(mVRMatrix, 0, mViewMatrix, 0, mRotationMatrix, 0);
Matrix.setIdentityM(mMVPMatrix, 0);
Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mVRMatrix, 0);
Matrix.scaleM(mMVPMatrix,0,mScale,mScale,mScale);
if (DrLine.size() > 0) {
for (Line LineX : DrLine) {
LineX.draw(mMVPMatrix);
}
}
if (DrPoint.size() > 0) {
for (Point PointX : DrPoint) {
PointX.draw(mMVPMatrix);
}
}
XLine.draw(mMVPMatrix);
YLine.draw(mMVPMatrix);
ZLine.draw(mMVPMatrix);
}
public void onSurfaceChanged(GL10 unused, int width, int height) {
GLES20.glViewport(0, 0, width, height);
ratio = (float) width / height;
//Matrix.frustumM(mProjectionMatrix, 0, -ratio*10, ratio*10, -10, 10, 1, 9);
Matrix.orthoM(mProjectionMatrix, 0, -ratio, ratio, -1.0f, 1.0f, -5.0f, 5.0f);
}
public static int loadShader(int type, String shaderCode){
// create a vertex shader type (GLES20.GL_VERTEX_SHADER)
// or a fragment shader type (GLES20.GL_FRAGMENT_SHADER)
int shader = GLES20.glCreateShader(type);
// add the source code to the shader and compile it
GLES20.glShaderSource(shader, shaderCode);
GLES20.glCompileShader(shader);
return shader;
}
private Float TempMaxPointHolder = 0.0f;
private Float MaxPointHolder = 0.0f;
public Float Scaler(){
Float TempScaler = 1.0f;
Iterator<ArrayList<String>> MaxPointFinder = PointArray.iterator();
while (MaxPointFinder.hasNext()){
ArrayList<String> MaxPoint = MaxPointFinder.next();
TempMaxPointHolder = Math.abs(Math.max(Math.max(Float.parseFloat(MaxPoint.get(1)),Float.parseFloat(MaxPoint.get(2))),Float.parseFloat(MaxPoint.get(3))));
if (TempMaxPointHolder > MaxPointHolder){
MaxPointHolder = TempMaxPointHolder;
}
}
TempScaler = 0.9f / MaxPointHolder;
return TempScaler;
}
public void Drawer(){
Float Scaler = Scaler();
Integer Lindex = 0;
ArrayList<Point> TempDrPoint = new ArrayList<Point>();
ArrayList<Line> TempDrLine = new ArrayList<Line>();
Iterator<ArrayList<String>> Litr = LineArray.iterator();
while (Litr.hasNext()) {
L = Litr.next();
Joint1 = Float.parseFloat(L.get(1));
Joint2 = Float.parseFloat(L.get(2));
Iterator<ArrayList<String>> PitrL = PointArray.iterator();
while (PitrL.hasNext()){
P = PitrL.next();
if (Float.parseFloat(P.get(0)) == Joint1) {
x1 = Float.parseFloat(P.get(1)) * Scaler;
y1 = Float.parseFloat(P.get(2)) * Scaler;
z1 = Float.parseFloat(P.get(3)) * Scaler;
}
if (Float.parseFloat(P.get(0)) == Joint2) {
x2 = Float.parseFloat(P.get(1)) * Scaler;
y2 = Float.parseFloat(P.get(2)) * Scaler;
z2 = Float.parseFloat(P.get(3)) * Scaler;
}
}
Line TempLine = new Line();
TempLine.SetVerts(x1, y1, z1, x2, y2, z2);
if (L.get(3) == "0") {
TempLine.SetColor(0.0f, 0.0f, 0.0f, 1.0f);
}
else if (L.get(3) == "1"){
TempLine.SetColor(0.66f, 0.73f, 0.21f, 1.0f);
}
TempDrLine.add(TempLine);
Lindex = Lindex + 1;
}
setDrLine(TempDrLine);
Integer Pindex = 0;
Iterator<ArrayList<String>> Pitr = PointArray.iterator();
while (Pitr.hasNext()){
P = Pitr.next();
px = Float.parseFloat(P.get(1)) * Scaler;
py = Float.parseFloat(P.get(2)) * Scaler;
pz = Float.parseFloat(P.get(3)) * Scaler;
ps = Float.parseFloat(P.get(4));
Point TempPoint = new Point();
TempPoint.SetPointVerts(px, py, pz);
if (ps == 0.0f) {
TempPoint.SetPointColor(0.65f, 0.37f, 0.11f, 1.0f);
}
else if (ps == 1.0f) {
TempPoint.SetPointColor(0.68f, 0.07f, 0.32f, 1.0f);
}
TempDrPoint.add(TempPoint);
Pindex = Pindex + 1;
}
setDrPoint(TempDrPoint);
}
public volatile float mXAngle;
public volatile float mYAngle;
public ArrayList<Line> getDrLine() {
return DrLine;
}
public ArrayList<Point> getDrPoint(){
return DrPoint;
}
public void setDrLine(ArrayList<Line> XDrLine) {
DrLine = XDrLine;
}
public void setDrPoint(ArrayList<Point> XDrPoint) {
DrPoint = XDrPoint;
}
public float getXAngle() {
return mXAngle;
}
public float getYAngle(){
return mYAngle;
}
public void setAngleX(float Xangle) {
mXAngle = Xangle;
}
public void setAngleY(float Yangle) {
mYAngle = Yangle;
}
public volatile float mScale = 1;
public volatile float mXFocus;
public volatile float mYFocus;
public void setZoom(float scale){
mScale = scale;
}
public void setFocus(float XFocus, float YFocus){
mXFocus = XFocus;
mYFocus = YFocus;
}
public float getmScale(){
return mScale;
}
public float getmXFocus(){
return mXFocus;
}
public float getmYFocus(){
return mYFocus;
}
public void setLineArray(ArrayList<ArrayList<String>> XLine){
LineArray = XLine;
}
public ArrayList<ArrayList<String>> getLineArray(){
return LineArray;
}
public void setUndoL(ArrayList<ArrayList<String>> UndoLine){
this.UndoL.add(new ArrayList<ArrayList<String>>(UndoLine));
}
public ArrayList<ArrayList<ArrayList<String>>> getUndoL() {
return UndoL;
}
public void setUndoP(ArrayList<ArrayList<String>> UndoPoint){
this.UndoP.add(new ArrayList<ArrayList<String>>(UndoPoint));
}
public ArrayList<ArrayList<ArrayList<String>>> getUndoP() {
return UndoP;
}
public void setPointArray(ArrayList<ArrayList<String>> XPoint){
PointArray = XPoint;
}
public ArrayList<ArrayList<String>> getPointArray(){
return PointArray;
}
gives error contents_sample_state: [ agr({[3 ,38]=11, [3 ,7 ,38]=28}) ]
public class Line {
private FloatBuffer VertexBuffer;
private final String VertexShaderCode =
// This matrix member variable provides a hook to manipulate
// the coordinates of the objects that use this vertex shader
"uniform mat4 uMVPMatrix;" +
"attribute vec4 vPosition;" +
"void main() {" +
// the matrix must be included as a modifier of gl_Position
" gl_Position = uMVPMatrix * vPosition;" +
"}";
private final String FragmentShaderCode =
"precision mediump float;" +
"uniform vec4 vColor;" +
"void main() {" +
" gl_FragColor = vColor;" +
"}";
protected int GlProgram;
protected int PositionHandle;
protected int ColorHandle;
protected int MVPMatrixHandle;
// number of coordinates per vertex in this array
static final int COORDS_PER_VERTEX = 3;
static float LineCoords[] = {
0.0f, 0.0f, 0.0f,
1.0f, 0.0f, 0.0f
};
private final int VertexCount = LineCoords.length / COORDS_PER_VERTEX;
private final int VertexStride = COORDS_PER_VERTEX * 4; // 4 bytes per vertex
// Set color with red, green, blue and alpha (opacity) values
float color[] = { 0.0f, 0.0f, 0.0f, 1.0f };
public Line() {
// initialize vertex byte buffer for shape coordinates
ByteBuffer bb = ByteBuffer.allocateDirect(
// (number of coordinate values * 4 bytes per float)
LineCoords.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(LineCoords);
// set the buffer to read the first coordinate
VertexBuffer.position(0);
int vertexShader = GLRender.loadShader(GLES20.GL_VERTEX_SHADER, VertexShaderCode);
int fragmentShader = GLRender.loadShader(GLES20.GL_FRAGMENT_SHADER, FragmentShaderCode);
GlProgram = GLES20.glCreateProgram(); // create empty OpenGL ES Program
GLES20.glAttachShader(GlProgram, vertexShader); // add the vertex shader to program
GLES20.glAttachShader(GlProgram, fragmentShader); // add the fragment shader to program
GLES20.glLinkProgram(GlProgram); // creates OpenGL ES program executables
}
public void SetVerts(float v0, float v1, float v2, float v3, float v4, float v5) {
LineCoords[0] = v0;
LineCoords[1] = v1;
LineCoords[2] = v2;
LineCoords[3] = v3;
LineCoords[4] = v4;
LineCoords[5] = v5;
VertexBuffer.put(LineCoords);
// set the buffer to read the first coordinate
VertexBuffer.position(0);
}
public void SetColor(float red, float green, float blue, float alpha) {
color[0] = red;
color[1] = green;
color[2] = blue;
color[3] = alpha;
}
public void draw(float[] mvpMatrix) {
// Add program to OpenGL ES environment
GLES20.glUseProgram(GlProgram);
// get handle to vertex shader's vPosition member
PositionHandle = GLES20.glGetAttribLocation(GlProgram, "vPosition");
// Enable a handle to the triangle vertices
GLES20.glEnableVertexAttribArray(PositionHandle);
// Prepare the triangle coordinate data
GLES20.glVertexAttribPointer(PositionHandle, COORDS_PER_VERTEX,
GLES20.GL_FLOAT, false,
VertexStride, VertexBuffer);
// get handle to fragment shader's vColor member
ColorHandle = GLES20.glGetUniformLocation(GlProgram, "vColor");
// Set color for drawing the triangle
GLES20.glUniform4fv(ColorHandle, 1, color, 0);
// get handle to shape's transformation matrix
MVPMatrixHandle = GLES20.glGetUniformLocation(GlProgram, "uMVPMatrix");
//GLRender.checkGlError("glGetUniformLocation");
// Apply the projection and view transformation
GLES20.glUniformMatrix4fv(MVPMatrixHandle, 1, false, mvpMatrix, 0);
//GLRender.checkGlError("glUniformMatrix4fv");
GLES20.glLineWidth(5);
// Draw the triangle
GLES20.glDrawArrays(GLES20.GL_LINES, 0, VertexCount);
// Disable vertex array
GLES20.glDisableVertexAttribArray(PositionHandle);
}
}
public class GLSurface extends GLSurfaceView {
//public static GLRender xRender;
ScaleGestureDetector ScaleDetect;
MainActivity mMain;
OpenGL XOPL = mMain.xOpenGL;
public GLSurface(Context context, AttributeSet attrs){
super(context, attrs);
// Render the view only when there is a change in the drawing data
//setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);
ScaleDetect = new ScaleGestureDetector(context, new ScaleDetectorListener());
}
private float mPreviousX;
private float mPreviousY;
float density = this.getResources().getDisplayMetrics().density;
private static final int MAX_CLICK_DURATION = 300;
private long pressStartTime;
#Override
public boolean onTouchEvent(MotionEvent e) {
ScaleDetect.onTouchEvent(e);
float x = e.getX();
float y = e.getY();
switch (e.getAction()) {
case MotionEvent.ACTION_MOVE:
if(!ScaleDetect.isInProgress()) {
float xMoveRange = x - mPreviousX;
float yMoveRange = y - mPreviousY;
float dx = 0.0f;
float dy = 0.0f;
float w = this.getWidth();
float h = this.getHeight();
if (Math.abs(xMoveRange) > w / 100 && Math.abs(yMoveRange) < h / 100){
dx = xMoveRange / density / 2.0f;
XOPL.xRender.setAngleX(XOPL.xRender.getXAngle() + dx);
}
if (Math.abs(xMoveRange) < w / 100 && Math.abs(yMoveRange) > h / 100){
dy = yMoveRange / density / 2.0f;
XOPL.xRender.setAngleY(XOPL.xRender.getYAngle() + dy);
}
XOPL.myGLView.requestRender();
}
break;
case MotionEvent.ACTION_DOWN:
pressStartTime = System.currentTimeMillis();
break;
case MotionEvent.ACTION_UP:
long pressDuration = System.currentTimeMillis() - pressStartTime;
if (pressDuration < MAX_CLICK_DURATION) {
float Nx = (x - Float.parseFloat(Double.toString(this.getWidth())) * 0.5f) / (Float.parseFloat(Double.toString(this.getWidth())) * 0.5f);
float Ny = (y - Float.parseFloat(Double.toString(this.getHeight())) * 0.5f) / (Float.parseFloat(Double.toString(this.getHeight())) * 0.5f);
float Nz = 1.0f;
XOPL.xRender.setNCoordinate(Nx, Ny, Nz);
XOPL.xRender.Selection();
XOPL.myGLView.requestRender();
}
break;
}
mPreviousX = x;
mPreviousY = y;
return true;
}
private float sizeCoef = 1;
public class ScaleDetectorListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
float scaleFocusX = 0;
float scaleFocusY = 0;
public boolean onScale(ScaleGestureDetector arg0) {
float scale = arg0.getScaleFactor() * sizeCoef;
sizeCoef = scale;
XOPL.xRender.setZoom(sizeCoef);
XOPL.myGLView.requestRender();
return true;
}
public boolean onScaleBegin(ScaleGestureDetector arg0) {
invalidate();
scaleFocusX = arg0.getFocusX();
scaleFocusY = arg0.getFocusY();
XOPL.xRender.setFocus(scaleFocusX,scaleFocusY);
return true;
}
public void onScaleEnd(ScaleGestureDetector arg0) {
scaleFocusX = 0;
scaleFocusY = 0;
XOPL.xRender.setFocus(scaleFocusX,scaleFocusY);
}
}
}

Not sure if this is the problem, but watch out for things like:
XOPL.xRender.setAngleX(XOPL.xRender.getXAngle() + dx)
... especially when using mediump precision in shaders. Generally I'd recommend changing setAngle functions to exploit rotational symmetry and wrap the value around so you get an absolute range used at the API-level of of +-Pi.
In your current code if the user keeps swiping in one direction, eventually you'll run our of bits and everything will either stop rotating (at best), or fail with infinities or NaN results (at worst).
Note using "-Pi to +Pi" is preferred to using "0 to +2Pi", because the sign-bit is free in most floating point representations so preserves more dynamic precision.
Example code:
public float wrapRadians(float angle) {
// If angle is negative ensure value is higher than minus pi
if (angle < 0) {
while (angle < -math.PI) {
angle += 2 * math.PI;
}
// Else angle is positive so ensure value is less than pi
} else {
while (angle > math.PI) {
angle -= 2 * math.PI;
}
}
return angle;
}
public float setXAngle(float XAngle) {
mXAngle = wrapRadians(XAngle);
}
public float setYAngle(float YAngle) {
mYAngle = wrapRadians(YAngle);
}

android OpenGL-Es gluProject results not accurate?

I want to overlay an icon on top of 3D models in my game. I'm using gluProject to get the screen coordinates of the centre point of the models, and then using that data to draw icons on a custom view:
In my renderer class:
private void projectScreenCoords(GLSurfaceView view, GraphicsEntity ge, GL10 gl){
MatrixGrabber matrixGrabber = new MatrixGrabber();
matrixGrabber.getCurrentModelView(gl);
float[] modelMat = matrixGrabber.mModelView;
matrixGrabber.getCurrentProjection(gl);
float[] projMat = matrixGrabber.mProjection;
gl.glMatrixMode(GL10.GL_MODELVIEW);
// view port
int[] viewport = new int[]{view.getTop(),view.getLeft(),view.getWidth(),view.getHeight()};
float[] vector = new float[4];
GLU.gluProject(ge.getTransform().tx, ge.getTransform().ty, ge.getTransform().tz, modelMat, 0, projMat, 0, viewport, 0, vector, 0);
ge.setScreenCoords(vector[0], viewport[3] - vector[1]);
}
and my custom view:
protected void onDraw (Canvas canvas){
Vector<GraphicsEntity> scene = renderer.getForegroundScene();
for(int i = 0;i<scene.size();i++){
GraphicsEntity ge = scene.get(i);
float[] xy = ge.getScreenCoords();
if(xy[0]>-1 && xy[1]>-1){
canvas.drawBitmap(bitmap, xy[0]-bitmapWidth/2, xy[1]-bitmapHeight/2, null);
}
invalidate();
}
}
and where I set my projection matrix:
protected void setProjectionMatrix(GL10 gl){
float ratio = (float) viewportWidth / viewportHeight;
gl.glMatrixMode(GL10.GL_PROJECTION);
gl.glLoadIdentity();
gl.glFrustumf(-ratio*zoom, ratio*zoom, -1*zoom, 1*zoom, nearPlane, farPlane);
}
However, the further from the centre of the screen, the further off the centre of the model the icon is drawn:
Clearly, if it was just the viewport size that was incorrect (due to the bars at the top/bottom) then the icons would be off just in the y-axis, but they are off in the x-axis as well. What am I missing / doing wrong? Also I haven't used the 3rd value returned by gluProject, but this always has a value of 0.7 so I'm not quite sure how it would be used if at all?
Using SDK version 7, I've tested this on multiple devices (ZTE Blade running android 2.1 and Kindle Fire running 2.3.4) with the same results. viewportWidth/Height and view.getWidth/Height() are the same, and view.getTop/Left() returns 0. The MatrixGrabber code works for gluUnProject, so I'm reasonably confident that isn't the problem
EDIT: here is the rest of my GL-related drawing code:
In renderer:
// camera variables
protected float FOV = 60.0f;
protected float nearPlane = 3;
protected float farPlane = 7;
protected float eyeX = 0;
protected float eyeY = 0;
protected float eyeZ = 0;
protected float centreX = 0;
protected float centreY = 0;
protected float centreZ = ((farPlane - nearPlane) / 2) + nearPlane;
protected float upX = 0;
protected float upY = 1;
protected float upZ = 0;
protected float viewportWidth;
protected float viewportHeight;
// user camera control variables
protected float zoom = 1;
protected float rotatedX = 0;
protected float rotatedY = 0;
protected boolean zoomed = true;
protected TrackingTransform tracking;
protected void setWorldTransform(GL10 gl){
gl.glMatrixMode(GL10.GL_MODELVIEW);
gl.glLoadIdentity();
// transforms the centre position to 0,0,0
gl.glTranslatef(-centreX, -centreY, -centreZ);
}
protected void setModelRotation(GL10 gl, GraphicsEntity ge){
if(ge.isTrackerball()){
gl.glRotatef(rotatedX, 1.0f, 0, 0);
gl.glRotatef(rotatedY, 0, -1.0f, 0);
if(tracking!=null){
synchronized(tracking){
tracking.transform(gl);
}
}
} else if(ge.isBackground()){
gl.glTranslatef(centreX, centreY, centreZ);
gl.glRotatef(rotatedX, 1.0f, 0, 0);
gl.glRotatef(rotatedY, 0, -1.0f, 0);
if(ge.isSkybox()==true){
ge.getTransform().sx = nearPlane + 1.0f;
ge.getTransform().sy = nearPlane + 1.0f;
ge.getTransform().sz = nearPlane + 1.0f;
ge.getTransform().tx = 0;
ge.getTransform().ty = 0;
ge.getTransform().tz = 0;
}
}
}
protected void setModelViewMatrix(GL10 gl){
gl.glMatrixMode(GL10.GL_MODELVIEW);
gl.glLoadIdentity();
// not used:
//GLU.gluLookAt(gl, eyeX, eyeY, eyeZ, centreX, centreY, centreZ, upX, upY, upZ);
}
#Override
public void onDrawFrame(GL10 gl) {
// Set up various things before drawing
gl.glFrontFace(GL10.GL_CW);
gl.glEnable(GL10.GL_CULL_FACE);
gl.glCullFace(GL10.GL_FRONT);
gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
gl.glEnable(GL10.GL_DEPTH_TEST);
// change projection matrix
float oldzoom = zoom;
zoom = 1.0f;
setProjectionMatrix(gl);
zoom = oldzoom;
// set global world transform (also changes to modelview)
setWorldTransform(gl);
// loop through and draw background models
for(int i = 0;i<backgroundGraphicsEntities.size();i++){
GraphicsEntity ge = backgroundGraphicsEntities.get(i);
SimpleTransform t = ge.getTransform();
int modelIndex = ge.getModelIndex();
if(modelIndex>=0){
gl.glPushMatrix();
setModelRotation(gl, ge);
t.transform(gl);
if(ge.isSprite() && gl11flag){
Sprite s = sprites.get(modelIndex);
s.draw((GL11) gl, ge);
} else {
Model m = models.get(modelIndex);
if(m!=null){
m.draw(gl);
}
}
gl.glPopMatrix();
}
if(i==0 && ge.isSkybox()){
// if skybox, reset depth bit
gl.glClear(GL10.GL_DEPTH_BUFFER_BIT);
}
}
gl.glClear(GL10.GL_DEPTH_BUFFER_BIT);
// change projection matrix (if zoomed)
setProjectionMatrix(gl);
// change back to modelview
gl.glMatrixMode(GL10.GL_MODELVIEW);
// loop through and draw models
for(int i = 0;i<graphicsEntities.size();i++){
GraphicsEntity ge = graphicsEntities.get(i);
SimpleTransform t = ge.getTransform();
int modelIndex = ge.getModelIndex();
if(modelIndex>=0){
gl.glPushMatrix();
setModelRotation(gl, ge);
t.transform(gl);
if(ge.isSprite() && gl11flag){
Sprite s = sprites.get(modelIndex);
s.draw((GL11) gl, ge);
} else {
Model m = models.get(modelIndex);
if(m!=null){
m.draw(gl);
}
if(projectScreenCoords){
projectScreenCoords(glSurfaceView, ge, gl);
}
}
gl.glPopMatrix();
}
}
#Override
public void onSurfaceChanged(GL10 gl, int width, int height) {
viewportWidth = width;
viewportHeight = height;
gl.glViewport(0, 0, width, height);
setProjectionMatrix(gl);
}
#Override
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
if(gl instanceof GL11){
gl11flag = true;
}
gl.glClearColor(0, 0, 0, 1);
gl.glShadeModel(GL10.GL_SMOOTH);
gl.glEnable(GL10.GL_DEPTH_TEST);
gl.glDepthMask(true);
//gl.glClearDepthf(1.0f);
gl.glDepthFunc(GL10.GL_LEQUAL);
//gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_FASTEST);
setProjectionMatrix(gl);
}
and then in SimpleTransform (i.e. what gets called when ge.getTransform().transform(gl) is called):
public void transform(GL10 gl) {
gl.glTranslatef(tx, ty, tz);
gl.glRotatef(rz, 0, 0, 1);
gl.glRotatef(ry, 0, 1, 0);
gl.glRotatef(rx, 1, 0, 0);
gl.glScalef(sx, sy, sz);
}
and for TrackingTransform:
#Override
public void transform(GL10 gl) {
gl.glTranslatef(-tx, -ty, -tz);
}
and finally in model.draw():
public void draw(GL10 gl){
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
// Pass the vertex buffer in
gl.glVertexPointer(3, GL10.GL_FLOAT, 0,
vertices);
int textureID = material.getTexture().getTextureID();
if(textureID>=0){
// Enable Textures
gl.glEnable(GL10.GL_TEXTURE_2D);
// Get specific texture.
gl.glBindTexture(GL10.GL_TEXTURE_2D, textureID);
// Use UV coordinates.
gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
// Pass in texture coordinates
gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, textureCoordinates);
}
// Pass in vertex normals
gl.glNormalPointer(GL10.GL_FLOAT, 0, normals);
gl.glEnableClientState(GL10.GL_NORMAL_ARRAY);
gl.glDrawElements(GL10.GL_TRIANGLES, numindices,GL10.GL_UNSIGNED_SHORT, indices);
gl.glDisableClientState(GL10.GL_NORMAL_ARRAY);
if(textureID>=0){
// Disable buffers
gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
}
gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
}

The problem wasn't in the gluProject code at all. In fact, it was to do with the translations done before calling gluProject:
In onDrawFrame:
Model m = models.get(modelIndex);
if(m!=null){
m.draw(gl);
gl.glTranslatef(-tracking.getTransform().tx, -tracking.getTransform().ty, -tracking.getTransform().tz);
if(tickcount % projectFrequency == 0 ){
projectScreenCoords(glSurfaceView, ge, gl);
}
}

Android OpenGLES drawing buffer, blank screen

Im trying to draw primitives using a FloatBuffer for my vertices and a ShortBuffer for the indexes. Everything works fine with no crashes or warnings but the screen is blank. I can draw with glDrawTexfOES without trouble.
If anyone could take a look at the code I would appreciate it alot.
public abstract class PrimitiveBase extends DrawableEntity {
protected float[] _vertices;
protected short[] _indices;
private FloatBuffer _verticesBuffer;
private ShortBuffer _indicesBuffer;
public PrimitiveBase(Sprite sprite, float x, float y) {
super(sprite, x, y);
}
protected abstract void setVertices();
#Override
public void draw(float x, float y, float scaleX, float scaleY) {
GL10 gl = GlSystem.getGl();
gl.glPushMatrix();
gl.glMatrixMode(GL10.GL_MODELVIEW);
gl.glLoadIdentity();
gl.glScalef(scaleX, scaleY, 1.0F);
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
gl.glVertexPointer(2, GL10.GL_FLOAT, 0, _verticesBuffer);
gl.glColor4f(1.0F, 0, 0, 0);
gl.glDrawElements(GL10.GL_TRIANGLES, _indices.length,
GL10.GL_UNSIGNED_SHORT, _indicesBuffer);
gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
gl.glPushMatrix();
}
#Override
public void load(EntityManager parent) {
setVertices();
ByteBuffer vbb = ByteBuffer.allocateDirect(_vertices.length * 4);
vbb.order(ByteOrder.nativeOrder());
_verticesBuffer = vbb.asFloatBuffer();
_verticesBuffer.put(_vertices);
_verticesBuffer.position(0);
ByteBuffer ibb = ByteBuffer.allocateDirect(_indices.length * 2);
ibb.order(ByteOrder.nativeOrder());
_indicesBuffer = ibb.asShortBuffer();
_indicesBuffer.put(_indices);
_indicesBuffer.position(0);
}
}
public class Rectangle extends PrimitiveBase {
private float _width;
private float _heigth;
public Rectangle(Sprite sprite, float x, float y, float width, float height) {
super(sprite, x, y);
_heigth = height;
_width = width;
}
#Override
protected void setVertices() {
_vertices = new float[8];
_indices = new short[] { 0, 1, 2, 0, 2, 3 };
_vertices[0] = getX() - (_width / 2);
_vertices[1] = getY() + (_heigth / 2);
_vertices[2] = getX() + (_width / 2);
_vertices[3] = getY() + (_heigth / 2);
_vertices[4] = getX() + (_width / 2);
_vertices[5] = getY() - (_heigth / 2);
_vertices[6] = getX() - (_width / 2);
_vertices[7] = getY() - (_heigth / 2);
}
}

Android OpenGL ES add object on touch

I am building a small Android application which will add a cube on user's touch. The z depth is always -10, screen is always in landscape mode. This question seems to be asked many times, but I cannot get it running, forgive me as I am newbie to opengl.
I am quite confused about the screen coordinate/window coordinate/object coordinate to use with the gluUnproject. As I understand, screen is when user touch and we get x and y from motion even. Window coordinate is when we load the identity, and object coordinate is when we transform the identity matrix to get object's coordinate. Is that right?
And here is my code, the matrix stacking is from android api sample. Please point out what I am doing wrong.
The drawing part:
public void draw(GL10 gl) {
for (GLObject glObject : list) {
if (glObject != null) {
gl.glLoadIdentity();
glObject.draw(gl);
}
}
gl.glMatrixMode(GL10.GL_MODELVIEW);
gl.glLoadIdentity();
if (isTouching) {
boolean addObject = false;
for (GLObject glObject : list) {
addObject = glObject.checkTouch(gl, x, y);
}
if (!addObject) {
i++;
Log.d("i", i + "");
addGLObject(gl);
}
isTouching = false;
}
}
Here is the code for adding object
private void getMatrix(GL10 gl, int mode, float[] mat) {
GLView.matrixTrackingGL.glMatrixMode(mode);
GLView.matrixTrackingGL.getMatrix(mat, 0);
}
public void addGLObject(GL10 gl) {
float[] XY = getWorldCoordinate(gl, x, y);
if (XY != null) {
// XY[0] = (float) (x - Main.SCREEN_WIDTH / 2) / 10;
//
// XY[1] = (float) (Main.SCREEN_HEIGHT / 2 - y) / 10;
GLObject glObject = new GLObject(colors, XY[0], XY[1]);
Log.d("Object position", "X: " + XY[0] + " Y: " + XY[1]);
list.add(glObject);
}
}
private float[] getWorldCoordinate(GL10 gl, int x, int y) {
float[] modelMatrix = new float[16];
float[] projMatrix = new float[16];
int[] viewport = {0, 0, Main.SCREEN_WIDTH, Main.SCREEN_HEIGHT};
getMatrix(gl, GL10.GL_MODELVIEW, modelMatrix);
getMatrix(gl, GL10.GL_PROJECTION, projMatrix);
float[] output = new float[4];
GLU.gluUnProject(x, viewport[1] + viewport[3] - y, -10, modelMatrix, 0, projMatrix, 0, viewport, 0, output, 0);
return new float[] {output[0]/output[3], output[1]/output[3]};
}
public class GLObject {
private float[] vertices = { 1.000000f, 1.000000f, -1.000000f, 1.000000f,
-1.000000f, -1.000000f, -1.000000f, -1.000000f, -1.000000f,
-1.000000f, 1.000000f, -1.000000f, 1.000000f, 1.000000f, 1.000000f,
1.000000f, -1.000001f, 1.000000f, -1.000000f, -1.000000f,
1.000000f, -1.000000f, 1.000000f, 1.000000f, };
private short[] faces = { 0, 1, 2, 0, 2, 3, 4, 7, 6, 4, 6, 5, 0, 4, 5, 0,
5, 1, 1, 5, 6, 1, 6, 2, 2, 6, 7, 2, 7, 3, 4, 0, 3, 4, 3, 7 };
private float[] colors;
private float[] rot = { 0.0f, 0.0f, 0.0f };
private Float positionX, positionY;
private int alpha = 0;
// Our vertex buffer.
private FloatBuffer vertexBuffer;
// Our index buffer.
private ShortBuffer faceBuffer;
public GLObject() {
init();
}
public GLObject(float[] colors, float x, float y) {
this.colors = colors.clone();
this.positionX = x;
this.positionY = y;
if (positionX.intValue() % 2 == 0) {
rot[0] = 1.0f;
} else {
if (positionY.intValue() % 2 == 0) {
rot[1] = 1.0f;
} else {
rot[2] = 1.0f;
}
}
init();
}
private void init() {
ByteBuffer vbb = ByteBuffer.allocateDirect(vertices.length * 4);
vbb.order(ByteOrder.nativeOrder());
vertexBuffer = vbb.asFloatBuffer();
vertexBuffer.put(vertices);
vertexBuffer.position(0);
ByteBuffer ibb = ByteBuffer.allocateDirect(faces.length * 2);
ibb.order(ByteOrder.nativeOrder());
faceBuffer = ibb.asShortBuffer();
faceBuffer.put(faces);
faceBuffer.position(0);
}
public boolean checkTouch(GL10 gl, int x, int y) {
boolean isTouched = false;
ByteBuffer pixels = ByteBuffer.allocate(4);
gl.glReadPixels(x, Main.SCREEN_HEIGHT - y, 1, 1, GL10.GL_RGBA,
GL10.GL_UNSIGNED_BYTE, pixels);
Log.d("COLOR",
pixels.get(0) + " " + pixels.get(1) + " " + pixels.get(2) + " "
+ pixels.get(3));
// isTouched always false to test always add object to screen
return isTouched;
}
public void draw(GL10 gl) {
// Counter-clockwise winding.
gl.glFrontFace(GL10.GL_CCW); // OpenGL docs
// Enable face culling.
gl.glEnable(GL10.GL_CULL_FACE); // OpenGL docs
// What faces to remove with the face culling.
gl.glCullFace(GL10.GL_BACK); // OpenGL docs
// Enabled the vertices buffer for writing and to be used during
// rendering.
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);// OpenGL docs.
// Enable color
gl.glColor4f(colors[0], colors[1], colors[2], 1.0f);
// Specifies the location and data format of an array of vertex
// coordinates to use when rendering.
gl.glPushMatrix();
gl.glTranslatef(positionX, positionY, -10);
// rotate
alpha += 1;
gl.glRotatef(alpha, rot[0], rot[1], rot[2]);
// draw
gl.glVertexPointer(3, GL10.GL_FLOAT, 0, // OpenGL docs
vertexBuffer);
gl.glDrawElements(GL10.GL_TRIANGLES, faces.length,// OpenGL docs
GL10.GL_UNSIGNED_SHORT, faceBuffer);
gl.glPopMatrix();
// Disable the vertices buffer.
gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); // OpenGL docs
// Disable face culling.
gl.glDisable(GL10.GL_CULL_FACE); // OpenGL docs
}
}
onDraw:
public void onDrawFrame(GL10 gl) {
// TODO Auto-generated method stub
// Clears the screen and depth buffer.
gl.glClear(GL10.GL_COLOR_BUFFER_BIT | // OpenGL docs.
GL10.GL_DEPTH_BUFFER_BIT);
gl.glMatrixMode(GL10.GL_PROJECTION);
// Reset the projection matrix
gl.glLoadIdentity();
GLU.gluPerspective(gl, 90.0f, Main.SCREEN_WIDTH/Main.SCREEN_HEIGHT, 3.0f, 100.0f);
gl.glMatrixMode(GL10.GL_MODELVIEW);
gl.glLoadIdentity();
GLU.gluLookAt(gl, 4.0f, 2.0f, 1.0f,
0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f);
// draw object
glObjectManager.draw(gl);
}

It has nothing to do with landscape mode, the problem is that you are translating your cube by -10 on the z axis. Try putting values of -100 and all the cubes will be at the center. Then try putting 0 for the z value (x, y, 0). The cubes will be much further out from the center of the screen and closer to where you expect them to be.
Look at http://tle.tafevc.com.au/toolbox/file/9495cce8-17b5-a8a5-d9b3-47c0c142d88d/1/sketches_and_drawings_lo.zip/3204a_20_reading_drawings/images/brick_perspective.jpg for an example of perspective projection. When the cube is at z=0, that is what is in the image. But when z=-10, it is closer to the center of the screen (the X) and smaller, because it follows the blue lines out to the horizon.

Problem drawing a sphere in OPENGL ES

I've been trying to create my own sphere using OpenGL ES and I followed the math described here http://www.math.montana.edu/frankw/ccp/multiworld/multipleIVP/spherical/learn.htm
However when I draw the sphere (just the vertices), just half of the sphere is been drawn. Can you please point to me what is the exact problem in the code that I am giving below:
public class Sphere {
static private FloatBuffer sphereVertex;
static private FloatBuffer sphereNormal;
static float sphere_parms[]=new float[3];
double mRaduis;
double mStep;
float mVertices[];
private static double DEG = Math.PI/180;
int mPoints;
/**
* The value of step will define the size of each facet as well as the number of facets
*
* #param radius
* #param step
*/
public Sphere( float radius, double step) {
this.mRaduis = radius;
this.mStep = step;
sphereVertex = FloatBuffer.allocate(40000);
mPoints = build();
Log.d("ALIS CHECK!!!!!!", " COUNT:" + mPoints);
}
public void draw(GL10 gl) {
gl.glFrontFace(GL10.GL_CW);
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
gl.glVertexPointer(3, GL10.GL_FLOAT, 0, sphereVertex);
gl.glColor4f(1.0f, 0.0f, 0.0f, 1.0f);
gl.glDrawArrays(GL10.GL_POINTS, 0, mPoints);
gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
}
private int build() {
/**
* x = p * sin(phi) * cos(theta)
* y = p * sin(phi) * sin(theta)
* z = p * cos(phi)
*/
double dTheta = mStep * DEG;
double dPhi = dTheta;
int points = 0;
for(double phi = -(Math.PI/2); phi <= Math.PI/2; phi+=dPhi) {
//for each stage calculating the slices
for(double theta = 0.0; theta <= (Math.PI * 2); theta+=dTheta) {
sphereVertex.put((float) (mRaduis * Math.sin(phi) * Math.cos(theta)) );
sphereVertex.put((float) (mRaduis * Math.sin(phi) * Math.sin(theta)) );
sphereVertex.put((float) (mRaduis * Math.cos(phi)) );
points++;
}
}
sphereVertex.position(0);
return points;
}
}
Also here is my renderer class:
/**
* These values are used to rotate the image by a certain value
*/
private float xRot;
private float yRot;
public void setxRot(float xRot) {
this.xRot += xRot;
}
public void setyRot(float yRot) {
this.yRot += yRot;
}
public GLViewRenderer(Context ctx) {
//initialize our 3D triangle here
mSphere = new Sphere(1, 25);
//Initializing the rate counter object
//This will help us in calculating the frames per second
fpsCalculator = new RateCounter(TAG);
fpsCalculator.start();
}
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
//initialize all the things required for openGL configurations
gl.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST);
}
public void onDrawFrame(GL10 gl) {
if(fpsCalculator != null)
fpsCalculator.countOnce();
//write the drawing code needed
gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
gl.glLoadIdentity();
/**
* Change this value in z if you want to see the image zoomed in
*/
gl.glTranslatef(0.0f, 0.0f, -5.0f);
gl.glRotatef(xRot, 0.0f, 1.0f, 0.0f);
gl.glRotatef(yRot, 1.0f, 0.0f, 0.0f);
mSphere.draw(gl);
}
public void onSurfaceChanged(GL10 gl, int width, int height) {
if(height == 0) {
height = 1;
}
gl.glViewport(0, 0, width, height);
gl.glMatrixMode(GL10.GL_PROJECTION);
gl.glLoadIdentity();
//Calculate The Aspect Ratio Of The Window
GLU.gluPerspective(gl, 45.0f, (float)width / (float)height, 0.1f, 100.0f);
gl.glMatrixMode(GL10.GL_MODELVIEW); //Select The Modelview Matrix
gl.glLoadIdentity(); //Reset The Modelview Matrix
}
/**
* Used to stop the FPS counter
*/
public void pause() {
if(fpsCalculator != null)
fpsCalculator.stop();
}
}
I'd really appreciate some help on this.
P.S: I tried changing CW to CCW still no luck
Thanks

Change this
for(double phi = -(Math.PI/2); phi <= Math.PI/2; phi+=dPhi)
to this
for(double phi = -(Math.PI); phi <= Math.PI; phi+=dPhi)

Actually, changing
for(double phi = -(Math.PI/2); phi <= Math.PI/2; phi+=dPhi)
to
for(double phi = -(Math.PI); phi <= 0; phi+=dPhi)
is enough. With phi from -(Math.PI) to +(Math.PI) you are making 360 degrees turn and counting each point twice. You can also do:
for(double phi = -(Math.PI); phi <= Math.PI; phi+=dPhi) {
for(double theta = 0.0; theta <= (Math.PI); theta+=dTheta) {
...
}
}
to avoid counting twice.