re. Finding the mouse coordinates in the 3d world

[DGENXP]

Hi

If this is possible could you help me please

If i wanted to select an object that is in the 3d world how would i go about finding the coordinates of the mouse in the 3d world so i could select the object that is closest to the mouse

Cheers
DGEN XP

[Ced666]

The mouse coordinates cannot be converted simply to a 3D position (because there is one dimension more). Instead, the mouse position can give you a ray that start from the camera position and goes 'inside' your screen. With that ray, you'll have to check for the collisions with other object.

Take a look at the function getRayFromScreenCoordinates from the ISceneCollisionManager. You can then use getCollisionPoint to check the collision with a triangle selector (constructed from a scene node).

[DGENXP]

Hi

Thank you for your quick reply

I have read the api and i am assuming that where pos is on the command i will need to place the x and y co-ordinates on the mouse position.

getRayFromScreenCoordinates ( core::position2d< s32 > pos, IsceneNode * camera = 0)

would i need to place the command in the while loop and now would i go by using this in my app

any further questions please post here.

[Ced666]

What do you want to do exactly ? Select a node when you click on it probably (that seems the most logical to me) ?
Then, why don't you simply check when you click with the mouse ? Don't need to calculate this all the time in a loop.

where pos is on the command i will need to place the x and y co-ordinates on the mouse position.

I don't get you. Could you be more specific ?

[Rambus]

To simply select an object in a 3d world, you dont need to know a virtual 3d cord for your mouse, you just need to use a pick command on the 2d cords where your mouse is at. (If thats what you want to do, read on)
ISceneNode* selectedSceneNode = smgr->getSceneCollisionManager()->getSceneNodeFromScreenCoordinatesBB(curs->getPosition());

were curs is your irrlicht cursor and smgr is your scene manager.
and thats all you have to do, to pick individual nodes, no fancy code
”Ì0D
Hope that helps!

[DGENXP]

Hi Thank you again for your reply.

ok my software creates an array that contains all of the floor tiles that are in my scene i will paste the code following to this. i would like to be able to select nodes that are in the array by clicking on them in order to do this i thought that you may need to also store all of the coordinates of each tile in an array as well

the below equation is not exactly what i am going to do it is just a brief description of what i want it to do
MPOS.X < Tile(i).X + 512 ( X = MPOS.X - Tile(i).X - X +Tile(i).x )

Below is the code that defines and places the tiles

Code: Select all

for (int Boxes = -Ammountofblocks*Ammountofblocks*1024*3; Boxes < 1024*Ammountofblocks*Ammountofblocks; Boxes+=1024) 
{ 
   nodes.push_back(smgr->addAnimatedMeshSceneNode(mesh)); 
} 

// Initialise the created nodes 

for (size_t i = 0; i < nodes.size(); ++i) 

{ 
 if (AblocksLine >= Ammountofblocks*1024) {Ablocksdown +=  1024;AblocksLine =-Ammountofblocks*1024;}
      nodes[i]->setMaterialFlag(EMF_LIGHTING, true); 
      nodes[i]->setMaterialTexture( 0, driver->getTexture("Objects/Floor10.jpg") );

      nodes[i]->setPosition(vector3df(AblocksLine,0,Ablocksdown)); 
  nodes[i]->setMaterialFlag(EMF_FOG_ENABLE,true);
AblocksLine +=1024;
//nodes[i]->setDebugDataVisible(true);
Tempy[i]=Ablocksdown ;
Tempx[i]=AblocksLine-1024;

} 

in the previous post by rambus how would i go about using it for my code

please ask if you have any more questions

cheers

DGENXP

[Halan]

hi,

i want to get a the point on a node from my mouse cursor position. i did like explained above and wrote this code:

Code: Select all

line3d<f32> line = smgr->getSceneCollisionManager()->getRayFromScreenCoordinates(device->getCursorControl->getPosition(), pCamera);

but it says

206 C:\Dokumente und Einstellungen\Kai\Eigene Dateien\age of war\Editor\main.cpp invalid use of member (did you forget the `&' ?)
206 C:\Dokumente und Einstellungen\Kai\Eigene Dateien\age of war\Editor\main.cpp base operand of `->' is not a pointer

but isnt everything in my code a pointer?

greets,
halan

[vitek]

getCursorControl is a function. You need to put parens after it so the compiler knows you are trying to call the function...

Code: Select all

device->getCursorControl()->getPosition();

[Halan]

yeah thanks

im stupid

greets,
halan