Draw a single pixel

[spyro]

Is the drawing of single pixels in Irrlicht possible, when not, how it could be done?
I've searched for this feature today, but I've found nothing.

Thanks for your help
spyro

[AndyCR]

you could always use drawrectangle (think thats the name, never used it) and just make the rectangle be one pixel.

[cadue]

but in this way there is a ugly performance! Using OPENGL is certain possible! there was a function, GL_BEGIN(POINT)... or at leas a similar funtion...sorry, i don't remember

[spyro]

Where can i find this function?
In the OpenGL libraries or in the basic functions of Irrlicht?
If the function is in the OpenGL libraries, could it be combined with Irrlicht or not?
PS: Sorry, for my English

spyro

[hybrid]

That method is from OpenGL. To integrate with Irrlicht it would be best to add a new method to IVideoDriver named draw3DPoint and add implementations for all video driver implementations.

[spyro]

It sounds a little bit difficult, isn't it?
But i will try it soon.
Thank's for your help!

spyro

[juliusctw]

hey spyro

if you got it workin , share it with us

[Emil_halim]

spyro:

you could integrate OpenGl stuff easlly with yor Irrlicht program, so you do not have to rechange the engine.

here is example that showing you how to a point. it is part from Magic Library.

Code: Select all

/****************************************
    draw a pixel by using OpenGl
        
        By Emil Halim

****************************************/


// ViewOrtho,ViewPerspective,Plot are
// parts of MagicLibrary.

#include "windows.h"
#include "gl/gl.h"
#include "gl/glu.h"
#include "gl/glaux.h"
#include "gl/glext.h"
#include <irrlicht.h>
using namespace irr;
using namespace core;
using namespace scene;
using namespace video;
using namespace io;



#pragma comment(lib, "Irrlicht.lib")
#pragma comment(lib,"opengl32.lib")


void ViewOrtho()            
{
 glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB_EXT, GL_MODULATE);
 glTexEnvf(GL_TEXTURE_ENV, GL_COMBINE_ALPHA_EXT, GL_MODULATE);
 glDisable(GL_LIGHTING);
 glDisable(GL_DEPTH_TEST);
 glDisable(GL_CULL_FACE);
 glMatrixMode(GL_PROJECTION);        
 glPushMatrix();            
 glLoadIdentity();           
 glOrtho( 0, 640 , 480 , 0, -10, 10 ); 
 glMatrixMode(GL_MODELVIEW);         
 glPushMatrix();            
 glLoadIdentity();           
}

void ViewPerspective()           
{
 glMatrixMode( GL_PROJECTION );        
 glPopMatrix();            
 glMatrixMode( GL_MODELVIEW );        
 glPopMatrix();            
 glEnable(GL_DEPTH_TEST);
 glEnable(GL_CULL_FACE);
}


void Plot (float x, float y)
{
    glBegin(0);
    glVertex2f(x,y);
    glEnd();
}

int main()
{
  IrrlichtDevice *device =
		createDevice( video::EDT_OPENGL, dimension2d<s32>(640, 480), 16);

  IVideoDriver* driver = device->getVideoDriver();
  ISceneManager* smgr = device->getSceneManager();

  while(device->run())
   {

          driver->beginScene(true, true, SColor(255,100,101,140));

		ViewOrtho();

                /// draw a pixel at 100,200
                Plot (100, 200);

                ViewPerspective();    
                
                smgr->drawAll();
		
		driver->endScene();
   }

   device->drop();
   return 0;
}

so as you see ,merging opengl is so easy.

hope it help you.

[hybrid]

Emil, the point is that this will work *ONLY* for OpenGL. Adding a generic point drawing routine would enable the use of any driver. Furthermore you could add several vertices to draw a point cloud in a performant way. Of course you could also add a driver check in the code, but adding an additional method would allow for easy integration with Irrlicht core. I guess that such basic but useful additions could easily make it into the core.

[Emil_halim]

ok hybrid, i got you idea.

but i really donot know how to draw 2D vertices in DirectX,so if anyone knows please post it to make it standard routine and adding it to the core of engine.

[spyro]

Looks cool!
I will try it with OpenGl and thanks for your help.

[spyro]

How can I use glColor4f(red, green, blue, alpha)?
I've tried it, but nothing happened.
Any Ideas?

Here is my current code (thanks to Emil_halim for his example):

Code: Select all

#include "gl/gl.h"

#include <irrlicht.h>
using namespace irr;
using namespace core;
using namespace scene;
using namespace video;
using namespace io;

int main()
{
    IrrlichtDevice *device = createDevice(EDT_OPENGL, dimension2d<s32>(800, 600), 16);

    IVideoDriver* driver = device->getVideoDriver();
  
    glOrtho( 0, 800 , 600 , 0, -10, 10 );           

    while(device->run())
    {
        driver->beginScene(true, true, SColor(0,255,255,255));
        glBegin(GL_POINTS);
        glColor4f(0,255,0,0);
        glVertex2f(10,10);
        glEnd();
        driver->endScene();
    }

    device->drop();
    return 0;
}

[vitek]

You might have a peek at the SVN version of SMaterial and the derived IVideoDriver implementations. Our friend hybird added a material flag that allows vertices to be rendered as points.

Oh, and the problem that you're seeing is most likely caused by not setting up any of the transforms.

Travis

[Emil_halim]

How can I use glColor4f(red, green, blue, alpha)?
I've tried it, but nothing happened.
Any Ideas?

Here is my current code (thanks to Emil_halim for his example):

Code: Select all

        glColor4f(0,255,0,0);
       

thanks spyro

the last parametr is the alpha value try to replace it with the next line

Code: Select all

       glColor4f(0,255,0,1.0);

Edited: this will work, i have test it.

Code: Select all

                driver->beginScene(true, true, SColor(0,0,0,0));

                 ViewOrtho();
                 glBegin(GL_POINTS);
                 glColor4f(0,255,0,1.0);
                 glVertex2f(10,10);
                 glEnd();
                 ViewPerspective();

                 smgr->drawAll();

	                 driver->endScene();

[spyro]

I've tried it but nothing changed.
Maybe the transforms cause this problem like vitek wrote.
I will see for it.

Edit: I've tried it and it works now! Thank you!