[SOLVED] Player::getScreenPosition not working correctly

[tolga]

Hi,

I have a BoundBox to convert into screen rectangle. The Player::getScreenPosition is not yielding correct results. In some cases, it's correct, others not. What is the basis of the conversion, what does (0, 0) mean, top-left or bottom-left?

Thanks.

[silent]

If getScreenPosition returns 0,0 it would mean that point was projected into the top left corner. It's not quite clear what do you mean by correct results or incorrect results?

Could you please show us minimal code so we can see correct / incorrect results?

Thanks!

 

[tolga]

Here's a piece of the code:

int x0, y0, x1, y1;
if (!player->getScreenPosition(x0, y0, bounds.minimum) ||
    !player->getScreenPosition(x1, y1, bounds.maximum))
{
  return;
}

float w = Unigine::Math::abs(x1 - x0) / zoomFactor;
float h = Unigine::Math::abs(y1 - y0) / zoomFactor;
float level = clamp(w > h ? w / App::getWidth() : h / App::getHeight(), 0.0f, 1.0f);

Vec2 center;
center.x = ((x0 + x1) / 2.0f) / App::getWidth();
center.y = ((y0 + y1) / 2.0f) / App::getHeight();

Basically the center is returning false values most of the time.

Edited June 30, 2022 by tolga

[tolga]

Oh forgot to mention center need to return in the range [0..1].

 

[tolga]

Ok I just confirmed that, the problem is on our side. It's a problem with the camera projection. Thanks for the help anyway.

[silent]

Yeah, internals of this method are pretty straightforward:

mat4 projection = getAspectCorrectedProjection(aspect);

	vec4 p = projection * vec4(modelview * Vec4(point, 1.0f));
	if (p.w <= 0.0f)
		return 0;

	x = 0.5f + p.x * 0.5f / p.w;
	y = 0.5f - p.y * 0.5f / p.w;
	return 1;

 

[tolga]

It looks like our camera transform is looking downwards and PlayerSpectator is correcting it automatically. Is it possible to get up-vector of a Mat4 or ensure it's looking upwards?

[tarragrum]

You can use
 

if (dot(mat4.getColumn3(1), vec3_up) > 0.9f) { // looking upwards! }