Text in Irrlicht

[Donald Duck]

I would like to make a sign with some text in Irrlicht. The text that I want to display on a sign is stored in a string. What can I use for this? I tried addBillboardTextSceneNode and addTextSceneNode, but the problem with these were that they rotated with the camera to always face the camera. That isn't realistic. I would like something that doesn't move compared to the rest of the scene no matter how I move the camera. How can I do this?

[CuteAlien]

You have to work with rendertarget textures (rtt's) for that. Meaning - you have a plane with a rtt on it. You set that texture as rendertarget and draw some text (usual text-drawing methods). Then the text will show up on that plane when it's rendered next. See RenderToTexture example for how to use rtt's (a short explanation - when using rtt's everything that usually would go to the screen will be put into a texture instead - and then you can use that texture again on models).

[Donald Duck]

Could you please post an example code for how to do that?

[CuteAlien]

In the RenderToTexture example add the following line after the first smgr->drawAll();

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env->getSkin()->getFont()->draw(L"And the programmer rendered to texture\nand see it showed up on the model\nand everything was good.", core::recti(10, 10, 100, 20), irr::video::SColor(255, 255,255, 255));
 

edit: You can certainly also replace the drawAll() - then only the text shows. Basically everything that would go onto the screen usually will go the rtt when you have set one.

[Donald Duck]

I can't get it to work in my code. I tried this and the cube was black:

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#include <irrlicht.h>
 
int main(){
    irr::IrrlichtDevice *device = irr::createDevice(irr::video::EDT_OPENGL);
    irr::video::IVideoDriver *driver = device->getVideoDriver();
    irr::scene::ISceneManager *sceneManager = device->getSceneManager();
 
    irr::scene::IMeshSceneNode *mesh = sceneManager->addCubeSceneNode();
    mesh->setMaterialTexture(0, driver->addRenderTargetTexture(irr::core::dimension2d<irr::u32>(256,256), "RTT1"));
 
    sceneManager->addCameraSceneNode(0, irr::core::vector3df(50, 70, 50), irr::core::vector3df(0, 0, 0));
 
    while(device->run()){
        device->getVideoDriver()->beginScene(true, true, irr::video::SColor(255, 255, 255, 255));
        device->getGUIEnvironment()->getSkin()->getFont()->draw(L"And the programmer rendered to texture\nand see it showed up on the model\nand everything was good.", irr::core::recti(10, 10, 100, 20), irr::video::SColor(255, 255,255, 255));
        device->getSceneManager()->drawAll();
        device->getGUIEnvironment()->drawAll();
        device->getVideoDriver()->endScene();
    }
 
    return 0;
}

What am I doing wrong?

[MartinVee]

Like CuteAlien said, try it with the RenderToTarget tutorial.

Add the line :

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device->getGUIEnvironment()->getSkin()->getFont()->draw(L"And the programmer rendered to texture\nand see it showed up on the model\nand everything was good.", irr::core::recti(10, 10, 100, 20), irr::video::SColor(255, 255,255, 255));
 

... beween the line :

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// draw whole scene into render buffer
smgr->drawAll();
 

... and the line :

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// set back old render target
// The buffer might have been distorted, so clear it
driver->setRenderTarget(0, true, true, 0);
 

[CuteAlien]

In your code you only create the rendertarget but never draw anything into it. You only do the normal rendering. You need to draw into that texture. The part in the example with the setRenderTarget stuff.

All those draw calls like font->draw(), scenemanager->drawAll, guiEnvironment->drawAll - they all draw into the currently set render target. Which by default is the screen. But you want to render the text first into a texture, that is why you have to set the texture as render-target. And then everything you draw will not end up in the screen but in that texture. And _then_ after you did draw into the texture you can use that texture to render to the screen (by setting the rendertarget back to 0 it will be back to drawing to screen).

[Donald Duck]

Thanks, this code works:

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#include <irrlicht.h>
 
int main(){
    irr::IrrlichtDevice *device = irr::createDevice(irr::video::EDT_OPENGL);
    irr::video::IVideoDriver *driver = device->getVideoDriver();
    irr::scene::ISceneManager *sceneManager = device->getSceneManager();
 
    irr::scene::IMeshSceneNode *mesh = sceneManager->addCubeSceneNode();
    irr::video::ITexture* rt = driver->addRenderTargetTexture(irr::core::dimension2d<irr::u32>(256,256), "RTT1");
    mesh->setMaterialTexture(0, rt);
    mesh->setMaterialFlag(irr::video::EMF_LIGHTING, false);
 
    sceneManager->addCameraSceneNode(0, irr::core::vector3df(50, 70, 50), irr::core::vector3df(0, 0, 0));
 
    while(device->run()){
        driver->beginScene(true, true, irr::video::SColor(255, 255, 255, 255));
        driver->setRenderTarget(rt, true, true, irr::video::SColor(0, 0, 0, 255));
        device->getGUIEnvironment()->getSkin()->getFont()->draw(L"And the programmer rendered to texture\nand see it showed up on the model\nand everything was good.", irr::core::recti(10, 10, 100, 20), irr::video::SColor(255, 255,255, 255));
        driver->setRenderTarget(0, true, true, irr::video::SColor(255, 255, 255, 255));
        sceneManager->drawAll();
        driver->endScene();
    }
 
    return 0;
}

[Donald Duck]

I've also created a function that makes it simple to apply text as a texture on a 3D element:

texttexture.cpp:

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#include <irrlicht.h>
#include <map>
#include "texttexture.h"
 
std::map<irr::video::ITexture*, irr::core::stringw> textTextures;
 
void addTextToSceneNode(irr::scene::ISceneNode *sceneNode, irr::core::stringw text){
    irr::video::ITexture* rt = driver->addRenderTargetTexture(irr::core::dimension2d<irr::u32>(256,256));
    sceneNode->setMaterialTexture(0, rt);
    textTextures[rt] = text;
}

texttexture.h:

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#include <irrlicht.h>
#include <map>
 
void addTextToSceneNode(irr::scene::ISceneNode *sceneNode, irr::core::stringw text);
extern std::map<irr::video::ITexture*, irr::core::stringw> textTextures;

Irrlicht main loop:

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while(device->run()){
    driver->beginScene(true, true, irr::video::SColor(255, 255, 255, 255));
    for(std::map<irr::video::ITexture*, irr::core::stringw>::iterator it = textTextures.begin(); it != textTextures.end(); it++){
        driver->setRenderTarget(it->first, true, true, irr::video::SColor(0, 0, 0, 255));
        device->getGUIEnvironment()->getSkin()->getFont()->draw(it->second, irr::core::recti(10, 10, 100, 20), irr::video::SColor(255, 0, 0, 0));
    }
    driver->setRenderTarget(0, true, true, irr::video::SColor(255, 255, 255, 255));
    sceneManager->drawAll();
    driver->endScene();
}

To use this to draw a texture on a 3D element (for example a cube), use this code:

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irr::scene::ISceneNode *myCube = sceneManager->addCubeSceneNode(1);    //draw a cube
addTextToSceneNode(myCube, L"This example text will be drawn on the cube");    //draw some text on the cube

[hendu]

You're drawing the text every frame there, just making sure you want to do that.