5.9.7 Clicking on Objects

This section describes how you can find out on which object a mouse has clicked.

The Code

Best way to explain this is by showing code:

iMeshWrapper* ClickedObject (iCamera* camera, int mousex, int mousey) { // Setup a 2D vector with our mouse position. We invert the y (based // on vertical screen dimension) because CS assumes y=0 is down for // 3D calculations. csVector2 v2d (mousex, camera->GetShiftY () * 2 - mousey); // We calculate the inverse perspective of this 2D point at z=100. // This results in a 3D position in camera space at z=100 that directly // corresponds to the 2D position we clicked on. // We use z=100 to ensure that we will at least hit all objects that // are before that distance. csVector3 v3d; camera->InvPerspective (v2d, 100, v3d); // We are going to cast a beam in the current sector of the camera // from our camera position in the direction of the 'v3d' point. // First we transform the v3d camera space location to world space. csVector3 startbeam = camera->GetTransform ().GetOrigin (); csVector3 endbeam = camera->GetTransform ().This2Other (v3d); csVector3 intersect; // Now do the actual intersection. iPolygon3D* poly = 0; iSector* beamsector = camera->GetSector (); iMeshWrapper* mesh = beamsector->HitBeam ( startbeam, endbeam, intersect, &poly); return mesh; }

Include Files

The include files useful for this section are:

#include "csgeom/transfrm.h" #include "iengine/camera.h" #include "iengine/sector.h" #include "iengine/mesh.h"