Develop Reference

OpenGL first steps with light and normals

I'm playing around with some basic OpenGL stuff and I'm trying to set up a simple square with lighting enabled, but the lighting is not correct so there is something wrong with my normals i guess.
Or is my understanding of normals totally wrong?
Here's my rendering code (btw I'm using lwjgl):
public class Renderer {
DisplayMode displayMode;
int i;
int width;
int height;
private boolean drawAxes = false;
private float rotation = 40.0f;
private float zoom = -20f;
// ----------- Variables added for Lighting Test -----------//
private FloatBuffer matSpecular;
private FloatBuffer lightPosition;
private FloatBuffer whiteLight;
private FloatBuffer lModelAmbient;
public Renderer(int width, int height) {
this.width = width;
this.height = height;
}
public static Renderer start() throws LWJGLException {
Renderer r = new Renderer(800, 600);
r.initContext();
r.run();
return r;
}
private void initContext() throws LWJGLException {
Display.setFullscreen(false);
DisplayMode d[] = Display.getAvailableDisplayModes();
for (int i = 0; i < d.length; i++) {
if (d[i].getWidth() == width && d[i].getHeight() == height && d[i].getBitsPerPixel() == 32) {
displayMode = d[i];
break;
}
}
Display.setDisplayMode(displayMode);
Display.create();
}
private void run() {
initGL();
while (!Display.isCloseRequested()) {
preRender();
render();
Display.update();
Display.sync(60);
}
Display.destroy();
}
private void initGL() {
GL11.glClearColor(0.0f, 0.0f, 0.0f, 0.0f); // Black Background
GL11.glClearDepth(1.0); // Depth Buffer Setup
GL11.glEnable(GL11.GL_DEPTH_TEST); // Enables Depth Testing
GL11.glDepthFunc(GL11.GL_LEQUAL); // The Type Of Depth Testing To Do
GL11.glMatrixMode(GL11.GL_PROJECTION); // Select The Projection Matrix
GL11.glLoadIdentity(); // Reset The Projection Matrix
// Calculate The Aspect Ratio Of The Window
GLU.gluPerspective(45.0f, (float) displayMode.getWidth() / (float) displayMode.getHeight(), 0.1f, 100.0f);
GL11.glMatrixMode(GL11.GL_MODELVIEW); // Select The Modelview Matrix
// Really Nice Perspective Calculations
GL11.glHint(GL11.GL_PERSPECTIVE_CORRECTION_HINT, GL11.GL_NICEST);
GL11.glPolygonMode(GL11.GL_FRONT_AND_BACK, GL11.GL_FILL);
initLightArrays();
glShadeModel(GL_SMOOTH);
glMaterial(GL_FRONT, GL_SPECULAR, matSpecular); // sets specular material color
glMaterialf(GL_FRONT, GL_SHININESS, 100.0f); // sets shininess
glLight(GL_LIGHT0, GL_POSITION, lightPosition); // sets light position
glLight(GL_LIGHT0, GL_SPECULAR, whiteLight); // sets specular light to white
glLight(GL_LIGHT0, GL_DIFFUSE, whiteLight); // sets diffuse light to white
glLightModel(GL_LIGHT_MODEL_AMBIENT, lModelAmbient); // global ambient light
glEnable(GL_LIGHTING); // enables lighting
glEnable(GL_LIGHT0); // enables light0
glEnable(GL_COLOR_MATERIAL); // enables opengl to use glColor3f to define material color
glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE); // tell opengl glColor3f effects the ambient and diffuse properties of material
}
private void preRender() {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
GL11.glTranslatef(0f, 0f, zoom);
GL11.glRotatef(-60f, 1f, 0f, 0f);
GL11.glRotatef(rotation, 0f, 0f, 1f);
}
private void render() {
FloatBuffer cBuffer = BufferUtils.createFloatBuffer(6*3);
float[] cArray = { 1f,1f,1f,
1f,1f,1f,
1f,1f,1f,
1f,1f,1f,
1f,1f,1f,
1f,1f,1f};
cBuffer.put(cArray);
cBuffer.flip();
FloatBuffer vBuffer = BufferUtils.createFloatBuffer(6*3);
float[] vArray = { 1f,1f,0f,
-1f,-1f,0,
1f,-1f,0,
1f,1f,0f,
-1f,1f,0,
-1f,-1f,0};
vBuffer.put(vArray);
vBuffer.flip();
FloatBuffer nBuffer = BufferUtils.createFloatBuffer(6*3);
float[] nArray = { 0f,0f,1f,
0f,0f,1f,
0f,0f,1f,
0f,0f,1f,
0f,0f,1f,
0f,0f,1f};
nBuffer.put(nArray);
nBuffer.flip();
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);
glEnableClientState(GL_NORMAL_ARRAY);
glColorPointer(3, 0, cBuffer);
glVertexPointer(3, 0, vBuffer);
glNormalPointer(3, nBuffer);
glDrawArrays(GL_TRIANGLES, 0, 6);
glDisableClientState(GL_COLOR_ARRAY);
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_NORMAL_ARRAY);
if (drawAxes) {
drawAxes(6);
}
glTranslatef(0.0f, 0.0f, 3);
glColor3f(0.1f, 0.4f, 0.9f);
}
public static void main(String[] args) throws LWJGLException {
System.setProperty("org.lwjgl.opengl.Display.allowSoftwareOpenGL", "true");
Renderer.start();
}

You are setting your normal pointer wrong:
glColorPointer(3, 0, cBuffer);
glVertexPointer(3, 0, vBuffer);
glNormalPointer(3, nBuffer);
The fixed-function GL might always expects normals to be 3-dimensional vectors, henze the size parameter (which tells the GL how many values are there in every vector) is not present in glNormalPointer. The 3 you are setting here is the stride parameter, which specifies the byte offset between consecutive array elements. Now 3 does not make any sence, it will interpret the second normal as to beginning 3 bytes into the arry, which means it combines the last byte of your first normal's x component together with 3 bytes from your first normal's y component when it reads the second normal'x s component, and so on...
Since your array is tightly packed, you can use the shortcut 0 here, like you do with the other pointers.
However, you must be aware that all of that is deprecated since almost a decade in OpenGL, modern core versions of OpenGL do not support the fixed function pipeline at all. If you are learning OpenGL nowadays, I strongly recommend you to learn modern, shader-based GL instead.

Without seeing more of your code, it's very difficult to see exactly what's going wrong.
However, I do see one thing that could be a problem:
FloatBuffer vBuffer = BufferUtils.createFloatBuffer(6*3);
float[] vArray = { 1f,1f,0f,
1f,-1f,0,
-1f,-1f,0,
1f,1f,0f,
-1f,1f,0,
-1f,-1f,0};
vBuffer.put(vArray);
vBuffer.flip();
The winding order on your triangles are not the same. The first triangle winds clockwise, whereas the second triangle winds counter-clockwise. You'll need to reorder the vertices to make sure that they wind in the same direction. OpenGL usually prefers things to wind counter-clockwise, so if I were you, I'd flip the first triangle.
If you're still getting the problem after you've done this, then post the rest of your draw code, as what you're showing here doesn't give a lot of information.

Applying map of the earth texture a Sphere

i been trying to implement a 3D animation in openGL (using JOGL) of a solar system so far i have 5 planets of different sizes but the problem i seem to be having is i cant add a map of the earth texture on a Sphere can anybody help me on how its done?
This is the code i have so far in my Display method:
#Override
public void display(GLAutoDrawable drawable) {
GL2 gl = drawable.getGL().getGL2();
GLU glu = new GLU();
gl.glClear(GL.GL_COLOR_BUFFER_BIT);
//make sure we are in model_view mode
gl.glMatrixMode(GL2.GL_MODELVIEW);
gl.glLoadIdentity();
glu.gluLookAt(10,20,20,0,3,0,0, 20, 0);
//gl.glMatrixMode(GL2.GL_PROJECTION);
//glu.gluPerspective(45,1,1,25);
//render ground plane
gl.glPushMatrix();
gl.glTranslatef(-10.75f, 3.0f, -1.0f);
gl.glColor3f(0.3f, 0.5f, 1f);
GLUquadric earth = glu.gluNewQuadric();
glu.gluQuadricDrawStyle(earth, GLU.GLU_FILL);
glu.gluQuadricNormals(earth, GLU.GLU_FLAT);
glu.gluQuadricOrientation(earth, GLU.GLU_OUTSIDE);
final float radius = 3.378f;
final int slices = 89;
final int stacks = 16;
glu.gluSphere(earth, radius, slices, stacks);
glu.gluDeleteQuadric(earth);
Texture earths;
try {
earths = TextureIO.newTexture(new File("earth.png"), true);
}
catch (IOException e) {
javax.swing.JOptionPane.showMessageDialog(null, e);
}
gl.glPopMatrix();
//gl.glEnd();
gl.glPushMatrix();
gl.glTranslatef(2.75f, 3.0f, -0.0f);
gl.glColor3f(0.3f, 0.5f, 1f);
GLUquadric earth1 = glu.gluNewQuadric();
glu.gluQuadricDrawStyle(earth1, GLU.GLU_FILL);
glu.gluQuadricNormals(earth1, GLU.GLU_FLAT);
glu.gluQuadricOrientation(earth1, GLU.GLU_OUTSIDE);
final float radius1 = 3.378f;
final int slices1 = 90;
final int stacks1 = 63;
glu.gluSphere(earth1, radius1, slices1, stacks1);
glu.gluDeleteQuadric(earth1);
gl.glPopMatrix();
gl.glPushMatrix();
gl.glTranslatef(3.75f, 6.0f, -7.20f);
gl.glColor3f(0.3f, 0.5f, 1f);
GLUquadric earth3 = glu.gluNewQuadric();
glu.gluQuadricDrawStyle(earth3, GLU.GLU_FILL);
glu.gluQuadricNormals(earth3, GLU.GLU_FLAT);
glu.gluQuadricOrientation(earth1, GLU.GLU_OUTSIDE);
final float radius3 = 1.878f;
final int slices3 = 89;
final int stacks3 = 16;
glu.gluSphere(earth3, radius3, slices3, stacks3);
glu.gluDeleteQuadric(earth3);
gl.glPopMatrix();
gl.glPushMatrix();
gl.glTranslatef(12.75f, 2.0f, -7.20f);
gl.glColor3f(0.3f, 0.5f, 1f);
GLUquadric earth4 = glu.gluNewQuadric();
glu.gluQuadricDrawStyle(earth4, GLU.GLU_FILL);
glu.gluQuadricNormals(earth4, GLU.GLU_FLAT);
glu.gluQuadricOrientation(earth4, GLU.GLU_OUTSIDE);
final float radius4 = 1.078f;
final int slices4 = 89;
final int stacks4 = 16;
glu.gluSphere(earth4, radius4, slices4, stacks4);
glu.gluDeleteQuadric(earth4);
gl.glPopMatrix();
gl.glPushMatrix();
gl.glTranslatef(2.75f, -6.0f, -0.0f);
gl.glColor3f(0.3f, 0.5f, 1f);
GLUquadric earth5 = glu.gluNewQuadric();
glu.gluQuadricDrawStyle(earth5, GLU.GLU_FILL);
glu.gluQuadricNormals(earth5, GLU.GLU_FLAT);
glu.gluQuadricOrientation(earth5, GLU.GLU_OUTSIDE);
final float radius5 = 3.778f;
final int slices5 = 90;
final int stacks5 = 63;
glu.gluSphere(earth5, radius5, slices5, stacks5);
glu.gluDeleteQuadric(earth5);
gl.glPopMatrix();
}

create your own sphere mesh
simple 2D loop through 2 angles (spherical coordinate system 2 Cartesian). You can easily add ellipsoid properties (earth is not a sphere) if you want more precision. If not then you can use single sphere mesh for all planets and just scale it before use ...
let a be the longitude and b the latitude so loop a from 0 to 2*PI [rad] and b from -0.5*PI to +0.5*PI [rad] where PI=3.1415... is the Pi (in C++ math.h it is called M_PI). If your math api uses degrees then convert to degrees PI [rad] = 180.0 [deg]
add necessary info per vertex
normals for lighting
// just unit sphere
nx=cos(b)*cos(a);
ny=cos(b)*sin(a);
nz=sin(b);
texture coordinate (assuming rectangle non distorted image)
// just convert a,b to <0,1> range
tx=a/(2.0*PI)
ty=(b/PI)+0.5;
vertex position
// just sphere(rx=ry=rz=r) or ellipsoid (rx=ry=equatorial and rz=polar radius)
// can also use rx*nx,ry*ny,rz*nz instead ...
x=rx*cos(b)*cos(a);
y=ry*cos(b)*sin(a);
z=rz*sin(b);
send all of this to OpenGL
so all above store in some memory space (CPU or GPU) and then send to rendering. You can use legacy glBegin(QUAD_STRIP); ... glEnd(); or displaylist/VBO/VAO. Bind the right texture before each planet/body and do not forget to update ModelView matrix too. This is how mine coordinate systems looks like:
Also have a look at these related Q/As:
realistic n-body solar system
sphere mesh by subdivision
[edit1] C++ example
//---------------------------------------------------------------------------
const int nb=15; // slices
const int na=nb<<1; // points per equator
class planet
{
public:
bool _init; // has been initiated ?
GLfloat x0,y0,z0; // center of planet [GCS]
GLfloat pos[na][nb][3]; // vertex
GLfloat nor[na][nb][3]; // normal
GLfloat txr[na][nb][2]; // texcoord
GLuint txrid; // texture id
GLfloat t; // dayly rotation angle [deg]
planet() { _init=false; txrid=0; x0=0.0; y0=0.0; z0=0.0; t=0.0; }
~planet() { if (_init) glDeleteTextures(1,&txrid); }
void init(GLfloat r,AnsiString texture); // call after OpenGL is already working !!!
void draw();
};
void planet::init(GLfloat r,AnsiString texture)
{
if (!_init) { _init=true; glGenTextures(1,&txrid); }
GLfloat x,y,z,a,b,da,db;
GLfloat tx0,tdx,ty0,tdy;// just correction if CLAMP_TO_EDGE is not available
int ia,ib;
// a,b to texture coordinate system
tx0=0.0;
ty0=0.5;
tdx=0.5/M_PI;
tdy=1.0/M_PI;
// load texture to GPU memory
if (texture!="")
{
Byte q;
unsigned int *pp;
int xs,ys,x,y,adr,*txr;
union { unsigned int c32; Byte db[4]; } c;
Graphics::TBitmap *bmp=new Graphics::TBitmap; // new bmp
bmp->LoadFromFile(texture); // load from file
bmp->HandleType=bmDIB; // allow direct access to pixels
bmp->PixelFormat=pf32bit; // set pixel to 32bit so int is the same size as pixel
xs=bmp->Width; // resolution should be power of 2
ys=bmp->Height;
txr=new int[xs*ys];
for(adr=0,y=0;y<ys;y++)
{
pp=(unsigned int*)bmp->ScanLine[y];
for(x=0;x<xs;x++,adr++)
{
// rgb2bgr and copy bmp -> txr[]
c.c32=pp[x];
q =c.db[2];
c.db[2]=c.db[0];
c.db[0]=q;
txr[adr]=c.c32;
}
}
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D,txrid);
glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S,GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T,GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE,GL_MODULATE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, xs, ys, 0, GL_RGBA, GL_UNSIGNED_BYTE, txr);
glDisable(GL_TEXTURE_2D);
delete bmp;
delete[] txr;
// texture coordinates by 1 pixel from each edge (GL_CLAMP_TO_EDGE)
tx0+=1.0/GLfloat(xs);
ty0+=1.0/GLfloat(ys);
tdx*=GLfloat(xs-2)/GLfloat(xs);
tdy*=GLfloat(ys-2)/GLfloat(ys);
}
// correct texture coordinate system (invert x)
tx0=1.0-tx0; tdx=-tdx;
da=(2.0*M_PI)/GLfloat(na-1);
db= M_PI /GLfloat(nb-1);
for (ib=0,b=-0.5*M_PI;ib<nb;ib++,b+=db)
for (ia=0,a= 0.0 ;ia<na;ia++,a+=da)
{
x=cos(b)*cos(a);
y=cos(b)*sin(a);
z=sin(b);
nor[ia][ib][0]=x;
nor[ia][ib][1]=y;
nor[ia][ib][2]=z;
pos[ia][ib][0]=r*x;
pos[ia][ib][1]=r*y;
pos[ia][ib][2]=r*z;
txr[ia][ib][0]=tx0+(a*tdx);
txr[ia][ib][1]=ty0+(b*tdy);
}
}
void planet::draw()
{
if (!_init) return;
int ia,ib0,ib1;
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glLoadIdentity();
glTranslatef(x0,y0,z0);
glRotatef(90.0,1.0,0.0,0.0); // rotate planets z axis (North) to OpenGL y axis (Up)
glRotatef(-t,0.0,0.0,1.0); // rotate planets z axis (North) to OpenGL y axis (Up)
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D,txrid);
glColor3f(1.0,1.0,1.0);
for (ib0=0,ib1=1;ib1<nb;ib0=ib1,ib1++)
{
glBegin(GL_QUAD_STRIP);
for (ia=0;ia<na;ia++)
{
glNormal3fv (nor[ia][ib0]);
glTexCoord2fv(txr[ia][ib0]);
glVertex3fv (pos[ia][ib0]);
glNormal3fv (nor[ia][ib1]);
glTexCoord2fv(txr[ia][ib1]);
glVertex3fv (pos[ia][ib1]);
}
glEnd();
}
glDisable(GL_TEXTURE_2D);
glMatrixMode(GL_MODELVIEW);
glPopMatrix();
}
//---------------------------------------------------------------------------
usage:
// variable to store planet (global)
planet earth;
// init after OpenGL initialisation
earth.init(1.0,"earth.bmp");
// position update
earth.x0= 0.0;
earth.y0= 0.0;
earth.z0=-20.0;
// add this to render loop
earth.draw(); // draws the planet
earth.t+=2.5; // just rotate planet by 2.5 deg each frame...
I know its ugly but it does not use any funny stuff just legacy OpenGL and Math.h (cos(),sin(),M_PI) and VCL for bitmap loading. So rewrite to your environment and you will be fine. Do not forget that each planet has its own texture so you need to have one txrid per planet so either have each planet as separate planet variable or rewrite ...

LWJGL Player Health bar not positioning properly

I'm making a game in Java using LWJGL and slick_util recently I'm trying to implement a health bar that will hover on top of the player's head. Problem is, it is not positioning correctly. The health bar's bottom left corner(from where OpenGL starts drawing) always appears at the top right corner of the player's rectangle, and when the player moves in either x or y or both, the health bar moves away from the player in the same direction. I think it might be a problem with the glTranslatef or perhaps something silly that I missed.
Render method of Player:
protected void render() {
Draw.rect(x, y, 32, 32, tex); //Player texture drawn
Draw.rect(x, y + 33, 32, 15, 1, 0, 0); //Health bar drawn. x is the same as player's, but y is +33 because I want it to hover on top
}
Draw class:
package rpgmain;
import static org.lwjgl.opengl.GL11.*;
import org.newdawn.slick.opengl.*;
/**
*
* #author Samsung
*/
public class Draw {
public static void rect(float x, float y, float width, float height, Texture tex) {
glEnable(GL_TEXTURE_2D);
glTranslatef(x, y, 0);
glColor4f(1f, 1f, 1f, 1f);
tex.bind();
glBegin(GL_QUADS); //Specifies to the program where the drawing code begins. just to keep stuff neat. GL_QUADS specifies the type of shape you're going to be drawing.
{
//PNG format for images
glTexCoord2f(0,1); glVertex2f(0, 0); //Specify the vertices. 0, 0 is on BOTTOM LEFT CORNER OF SCREEN.
glTexCoord2f(0,0); glVertex2f(0, height); //2f specifies the number of args we're taking(2) and the type (float)
glTexCoord2f(1,0); glVertex2f(width, height);
glTexCoord2f(1,1); glVertex2f(width, 0);
}
glEnd();
glDisable(GL_TEXTURE_2D);
}
public static void rect(float x, float y, float width, float height, float r, float g, float b) {
glDisable(GL_TEXTURE_2D);
glTranslatef(x, y, 0);
glColor3f(r, g, b);
glBegin(GL_QUADS); //Specifies to the program where the drawing code begins. just to keep stuff neat. GL_QUADS specifies the type of shape you're going to be drawing.
{
glVertex2f(0, 0); //Specify the vertices. 0, 0 is on BOTTOM LEFT CORNER OF SCREEN.
glVertex2f(0, height); //2f specifies the number of args we're taking(2) and the type (float)
glVertex2f(width, height);
glVertex2f(width, 0);
}
glEnd();
glEnable(GL_TEXTURE_2D);
}
}

I think your problem is with matrices. When you call glTranslatef, you are transforming the OpenGL ModelView matrix. However, since OpenGL is a state-based machine, this transformation is preserved for further drawing events. The second rectangle will be translated twice. What you want to do is use the OpenGL matrix stack. I'll rewrite one of the draw methods here:
public static void rect(float x, float y, float width, float height, Texture tex) {
glEnable(GL_TEXTURE_2D);
glPushMatrix();
glTranslatef(x, y, 0);
glColor4f(1f, 1f, 1f, 1f);
tex.bind();
glBegin(GL_QUADS);
{
glTexCoord2f(0,1); glVertex2f(0, 0);
glTexCoord2f(0,0); glVertex2f(0, height);
glTexCoord2f(1,0); glVertex2f(width, height);
glTexCoord2f(1,1); glVertex2f(width, 0);
}
glEnd();
glPopMatrix();
glDisable(GL_TEXTURE_2D);
}
The line glPushMatrix() will add a new matrix to the top of the stack. All transformations from this point on will be applied to the newly added matrix. Then, when you call glPopMatrix(), the matrix is discarded and the stack is returned to it's previous state.

LWJGL - Switching from 3D to 2D to render text with NO external librarys

I want to render 2D quads on my screen by switching to a 2D scene then switching back to 3D.
I dont want to use any external librarys besides LWJGL.
This is what I got so far:
private static void renderLetter(char c, float x, float y) {
int character = c+1;
GL11.glPushMatrix();
setOrthoOn();
GL11.glTranslatef(x, y, 0);
float[] xy = game.getResourceManager().getSpriteSheets().get(fontSheet).getXYForCell(character);
float cellx = game.getResourceManager().getSpriteSheets().get(fontSheet).getCell_sizeX();
float celly = game.getResourceManager().getSpriteSheets().get(fontSheet).getCell_sizeY();
float xx = xy[0];
float yy = xy[1];
GL11.glBindTexture(GL11.GL_TEXTURE_2D, game.getResourceManager().getTextures().get(game.getResourceManager().getSpriteSheets().get(fontSheet).getTextureID()));
GL11.glBegin(GL11.GL_QUADS);
GL11.glTexCoord2f(xx, yy);
GL11.glVertex2f(0,0);
GL11.glTexCoord2f(xx+cellx, yy);
GL11.glVertex2f(fontSize,0);
GL11.glTexCoord2f(xx+cellx, yy+celly);
GL11.glVertex2f(fontSize,fontSize);
GL11.glTexCoord2f(xx, yy+celly);
GL11.glVertex2f(0,fontSize);
GL11.glEnd();
GL11.glBindTexture(GL11.GL_TEXTURE_2D, 0);
setOrthoOff();
GL11.glPopMatrix();
}
public static void setOrthoOn()
{
GL11.glDisable(GL11.GL_LIGHTING);
GL11.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
GL11.glClearDepth(1);
GL11.glViewport(0,0,1360,768);
GL11.glMatrixMode(GL11.GL_MODELVIEW);
GL11.glMatrixMode(GL11.GL_PROJECTION);
GL11.glLoadIdentity();
GL11.glOrtho(0, 1360, 768, 0, 1, -1);
GL11.glMatrixMode(GL11.GL_MODELVIEW);
GL11.glLoadIdentity();
}
public static void setOrthoOff()
{
GL11.glMatrixMode(GL11.GL_PROJECTION);
GL11.glLoadIdentity();
GLU.gluPerspective(game.getFieldOfView(), 1360f/768f, 0.1f, 1000);
GL11.glMatrixMode(GL11.GL_MODELVIEW);
GL11.glLoadIdentity();
GL11.glEnable(GL11.GL_DEPTH_TEST);
GL11.glDepthFunc(GL11.GL_LEQUAL);
GL11.glHint(GL11.GL_PERSPECTIVE_CORRECTION_HINT, GL11.GL_NICEST);
}
the first method is to render a letter. what I am trying to do is by calling setOrthoOn switch to 2D rendering then render the quad then call setOrthoOff to switch back to 3D.
This code does nothing for me when I run it.. What am I doing wrong?

This should do it.
Note: some of the code may be extraneous. I'm not very experienced with OpenGL, but this worked for me. I would also recommend you import GL11 staticly. That way you don't have to type "GL11.BlaBlaBla", you can just type "BlaBlaBla".

OpenGL "Invalid operation error" After glDrawElements function on android phone

I can't run my app on my phone, and I'v located the error, yet lack the knowledge in programming and in english to repair it.
The app run's on emulator perfectly, without any errors in code neither in opengl. Yet on the phone everything runs fine without any errors, but show no opengl elements which i want to draw. I'v added glGetError almost everythere in my code, and found the error 1282 generated after glDrawElements which is GL_INVALID_OPERATION.
GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to an
enabled array or the element array and the buffer object's data store is currently mapped.
GL_INVALID_OPERATION is generated if glDrawElements is executed between
the execution of glBegin and the corresponding glEnd.
I have no glBegin or glEnd in my code, so i guess the problem is in my indexbuffer. Below i present you everthing i have with the indexbuffer.
private ShortBuffer _indexBuffer;
public void onDrawFrame(GL10 gl) {
FramesPerSecond.StartCounter();
gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
gl.glVertexPointer(3, GL10.GL_FLOAT, 0, _vertexBuffer);
gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]);
gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, textureBuffer);
for (int i = 1; i <= 10; i++) {
gl.glLoadIdentity();
gl.glTranslatef(0.0f, -1f, -1.0f + -1.5f * i);
gl.glRotatef(-_xAngle, 1f, 0f, 0f);
gl.glRotatef(-_yAngle, 0f, 1f, 0f);
gl.glDrawElements(GL10.GL_TRIANGLES, _nrOfVertices, GL10.GL_UNSIGNED_SHORT, _indexBuffer);
Log.e("Warning", " error code " +gl.glGetError());
}
Code of buffer in my object initialization function:
short[] indeksai = new short[] {
0, 1, 3,
0, 2, 1,
0, 3, 2,
1, 2, 3,
};
ByteBuffer ibb = ByteBuffer.allocateDirect(indeksai.length * 2);
ibb.order(ByteOrder.nativeOrder());
_indexBuffer = ibb.asShortBuffer();
_indexBuffer.put(indeksai);
And that's basicaly everything i have done with this buffer.
On surfaceCreated function >>
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
Log.i(LOG_TAG, "onSurfaceCreated()");
gl.glMatrixMode(GL10.GL_PROJECTION);
float ratio = _width / _height;
gl.glOrthof(-1, 1, -1 / ratio, 1 / ratio, 0.01f, 100.0f);
gl.glViewport(0, 0, (int) _width, (int) _height);
gl.glMatrixMode(GL10.GL_MODELVIEW);
gl.glEnable(GL10.GL_DEPTH_TEST);
gl.glClearColor(0f, 0f, 0f, 1.0f);
gl.glEnable(GL10.GL_CULL_FACE);
gl.glFrontFace(GL10.GL_CCW);
gl.glCullFace(GL10.GL_BACK);
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
gl.glEnableClientState(GL10.GL_COLOR_ARRAY);
initTriangle(gl, context);
try {
loadGLTexture(gl);
} catch (IOException e) {
Log.w(LOG_TAG, "Texture fail");
}
gl.glEnable(GL10.GL_TEXTURE_2D);
gl.glShadeModel(GL10.GL_SMOOTH);
gl.glClearColor(0.0f, 0.0f, 0.0f, 0.5f);
gl.glClearDepthf(1.0f);
gl.glEnable(GL10.GL_DEPTH_TEST);
gl.glDepthFunc(GL10.GL_LEQUAL);
gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST);
}

It's most likely because you're enabling GL_COLOR_ARRAY but never actually setting the glColorPointer. Try commenting out the gl.glEnableClientState(GL10.GL_COLOR_ARRAY); line.