calling LWJGL methods directly

[raft]

hello,

what should i do to call opengl methods directly after jPCT has done ? for example the code below doesnt draw a line

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while (loop) {
    // do jPCT things
    world.renderScene(buffer);
    world.draw(buffer);
    buffer.update();

    // do lwjgl things
    GL11.glBegin(GL11.GL_LINES);
    GL11.glVertex2f(10, 10);
    GL11.glVertex2f(50, 50);
    GL11.glEnd();

    buffer.displayGLOnly();
    Thread.sleep(10);
}


[EgonOlsen]

Hmmm...looks fine to me. If it doesn't work out, you may try to wrap your code into an IPostProcessor instead.

[raft]

onfortunately didnt help  this is version 1.17

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buffer.addPostProcessor(new IPostProcessor(){
private boolean initialized = false;

public void dispose() {
initialized = false;
}

public void init(FrameBuffer buffer) {
initialized = true;
}

public boolean isInitialized() {
return initialized;
}

public void process() {
GL11.glColor3f(255, 255, 255);
GL11.glBegin(GL11.GL_LINES);
GL11.glVertex2f(10, 10);
GL11.glVertex2f(50, 50);
GL11.glEnd();

}
});


[EgonOlsen]

Which renderer is this? GL or AWTGL?

[raft]

GL. just a simple addition to HelloWorldOGL sample

[EgonOlsen]

Have you tried to add a

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GL11.glDisable(GL11.GL_DEPTH_TEST);


before and a

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GL11.glEnable(GL11.GL_DEPTH_TEST);

after your code?

[raft]

didnt help neither  i know nothing about opengl so i may be forgotting something stupid.. does it work for you ?

[EgonOlsen]

This works:

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GL11.glMatrixMode(GL11.GL_MODELVIEW);
       GL11.glPushMatrix();
GL11.glLoadIdentity();
GL11.glMatrixMode(GL11.GL_PROJECTION);
GL11.glPushMatrix();
GL11.glLoadIdentity();
GL11.glOrtho(0, 1, 1, 0, 0.1, 100);
   
      GL11.glColor3f(255, 255, 255);
      GL11.glDisable(GL11.GL_TEXTURE_2D);
      GL11.glBegin(GL11.GL_LINES);
      GL11.glVertex3f(0.0f, 0.0f, -1f);
      GL11.glVertex3f(1.0f, 1.0f, -1f);
      GL11.glEnd();
      GL11.glEnable(GL11.GL_TEXTURE_2D);
     
      GL11.glMatrixMode(GL11.GL_PROJECTION);
      GL11.glPopMatrix();
      GL11.glMatrixMode(GL11.GL_MODELVIEW);
      GL11.glPopMatrix();


i.e. switch to Ortho-mode, use normalized screen coordinates and disable texturing.

[raft]

that worked for me too  but are all that stuff necessary ? and why glVertex3f ? i tried different z values, seems as a negative value is necessary but why ?

sorry, i know this is not a jPCT thing but 

[EgonOlsen]

It's required to give it a z-value that won't be clipped. I'm sure it's possible to set up OpenGL in a way that this isn't needed anymore, but that would require even more state changes before and after. Ortho mode is required, because otherwise the normal perspective transformations apply for your line, which isn't what you want for a 2d line.

[raft]

i see thank you and i guess this is the way to set it it up for 2D: (looking at FengGui source)

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GLU.gluOrtho2D(0, 800, 600, 00);


[EgonOlsen]

I still prefer the normalized coordinates. If you want to get rid of the z-value, try this instead:

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GL11.glOrtho(0, 1, 1, 0, 0.0f, 0.1f);


In addition, this doesn't force you to include GLU.

[raft]

indeed i need exact coordinates. so will it be like

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GL11.glOrtho(0, width, height, 0, 0.0f, 0.1f);

[EgonOlsen]

indeed i need exact coordinates. so will it be like

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GL11.glOrtho(0, width, height, 0, 0.0f, 0.1f);

In that case, yes!

[raft]

that code makes y axis increase downwards. is it also possible to convert mouse coordinate system ?