[SOLVED] Unigine::getScreenPosition() not working as expected

[ivan.cuevas]

Hi all,

I'm usnig this function to compute widget position from node(WorldExpression) absolute world position, at each update I call this function to update Gui widget position. This node is under player persecutor and its target.

For some angles (when persecutor is under target) function returns 0.

 

I've modified the source code just to log values as follows:

int getScreenPosition(Vec3 point,int &x,int &y) {
 Player player = getPlayer();
 if(player == NULL) return 0;
 int width = engine.app.getWidth();
 int height = engine.app.getHeight();
 mat4 projection = player.getProjection();
 Mat4 modelview = player.getModelview();
 projection.m00 *= float(height) / width;
 vec4 p = projection * vec4(modelview * Vec4(point,1.0f));
 log.message("--\n\tpoint:%s\n\tprojection:%s\n\tmodelview:%s\n\tp:%s",
  print_vec3(point),
  print_mat4(projection),
  print_mat4(modelview),
  print_vec4(p));
 if(p.w > 0.0f) {
  x = int(width * (0.5f + p.x * 0.5f / p.w));
  y = int(height * (0.5f - p.y * 0.5f / p.w));
  return 1;
 }
 return 0;
}

 

and this is what logs shows:

14:08:07 --
14:08:07 	point:[0.0000,0.0000,-107.0000]
14:08:07 	projection:[0.9743,0.0000,0.0000,0.0000] [0.0000,1.7321,0.0000,0.0000] [0.0000,0.0000,-1.0000,-0.2000] [0.0000,0.0000,-1.0000,0.0000]
14:08:07 	modelview:[0.4391,-0.8984,-0.0000,-0.0000] [-0.2548,-0.1246,0.9589,-2.8768] [-0.8615,-0.4211,-0.2836,-21.1491] [0.0000,0.0000,0.0000,1.0000]
14:08:07 	p:[-0.0000,-182.7014,-9.3995,-9.1993]
14:08:07 --
14:08:07 	point:[0.0000,0.0000,-107.0000]
14:08:07 	projection:[0.9743,0.0000,0.0000,0.0000] [0.0000,1.7321,0.0000,0.0000] [0.0000,0.0000,-1.0000,-0.2000] [0.0000,0.0000,-1.0000,0.0000]
14:08:07 	modelview:[0.4391,-0.8984,-0.0000,-0.0000] [-0.2548,-0.1246,0.9589,-2.8768] [-0.8615,-0.4211,-0.2836,-21.1491] [0.0000,0.0000,0.0000,1.0000]
14:08:07 	p:[-0.0000,-182.7014,-9.3995,-9.1993]
14:08:07 --
14:08:07 	point:[0.0000,0.0000,-107.0000]
14:08:07 	projection:[0.9743,0.0000,0.0000,0.0000] [0.0000,1.7321,0.0000,0.0000] [0.0000,0.0000,-1.0000,-0.2000] [0.0000,0.0000,-1.0000,0.0000]
14:08:07 	modelview:[0.4391,-0.8984,-0.0000,-0.0000] [-0.2548,-0.1246,0.9589,-2.8768] [-0.8615,-0.4211,-0.2836,-21.1491] [0.0000,0.0000,0.0000,1.0000]
14:08:07 	p:[-0.0000,-182.7014,-9.3995,-9.1993]

As p.w < 0, the x and y values are not updated, and functions exits with 0.

 

Any suggestion?

Ivan.

[frustum]

That is correct behaviour for this function. The target point isn't visible when the p.w < 0 (it's behind the camera for example).

[ivan.cuevas]

Understood :)

 

Thanks.