View.draw(GL_POINTS, points) - point size?

thomthom

On my home computer (nVidia Geforce 8800 GT) when I use this:
view.draw(GL_POINTS, points)
I end up with points of about 5px size.

On my work computer (ATI Radeon HD 4870 X2) and my co-workers computer (Quadro 3700FX) they are 1px - barely visible. How on earth does one control the size of the point?

TIG

view.line_width=5
called just before the draw command...
???

thomthom

No - no effect.

And view.draw_points is not the same either. view.draw_points will draw the points even if they are blocked by other geometry. view.draw(GL_POINTS, points) will ensure that point behind other geometry is not drawn - which is what I need.

thomthom

I wonder if something indirectly sets the point size...

http://newsgroups.derkeiler.com/Archive/Comp/comp.graphics.api.opengl/2008-09/msg00136.html
http://processing.org/discourse/yabb2/YaBB.pl?board=OpenGL;action=display;num=1217367002
http://www.gamedev.net/community/forums/topic.asp?topic_id=333237

Can one send commands to the SU OpenGL from Ruby?

thomthom

I found a hacky workaround:


def draw_points(points, color, view)
	return if points.is_a?(Array) && points.empty?
	#view.line_width = 5 # Does not appear to work
	view.drawing_color = color
	#view.draw(GL_POINTS, points) # How does one set point size?
	# http://newsgroups.derkeiler.com/Archive/Comp/comp.graphics.api.opengl/2008-09/msg00136.html
	# http://processing.org/discourse/yabb2/YaBB.pl?board=OpenGL;action=display;num=1217367002
	# http://www.gamedev.net/community/forums/topic.asp?topic_id=333237
	points = [points] if points.is_a?(Geom;;Point3d)
	points = [points] if points.is_a?(Array) && points.length == 3 && points.all?{ |i| i.is_a?(Numeric) }
	half_size = 2
	view.line_width = half_size * 2
	hack_points = []
	points.each { |p|
		# This hack doesn't work because of another bug that makes the polygons render black.
		#size = view.pixels_to_model(5, p)
		#hack_points << p.offset(view.camera.xaxis + view.camera.yaxis.reverse, size)
		#hack_points << p.offset(view.camera.yaxis.reverse + view.camera.xaxis.reverse, size)
		#hack_points << p.offset(view.camera.xaxis.reverse + view.camera.yaxis, size)
		#hack_points << p.offset(view.camera.yaxis + view.camera.xaxis, size)
		
		# But this might be better in any case as it only computes two points.
		offset_length = view.pixels_to_model(half_size, p)
		hack_points << p.offset(view.camera.xaxis.reverse, offset_length)
		hack_points << p.offset(view.camera.xaxis, offset_length)
	}
	#view.draw(GL_QUADS, hack_points)
	view.draw(GL_LINES, hack_points)
end

But I would still like to know why my home computer renders the points with a size, and all the work computers render them as just a pixel point. grumble

Chris Fullmer

I've never seen that render them any differen than what is specified in the arguments. It never returned any error?

thomthom

@chris fullmer said:

I've never seen that render them any differen than what is specified in the arguments. It never returned any error?

It's odd - I used view.draw(GL_POINTS, points) in a futile desperate attempt to see what happened. I expected it would work as view.draw_points without the ability to specify type and size. But for some reason on my home computer it rendered as ca 5px circles...
So I thought it was a fixed shape+size - until I came into work and tested it - just for the sake of it. Then I only got single pixels.
So now I convert the points into line segments and draw them. Not sure how that impacts performance - but at the moment it's the only thing I can work out how to control.

When I get home I'll disable all other plugins and see if there's something there...

jessejames

@thomthom said:

How on earth does one control the size of the point?

in OpenGL it's as simple as

glPointSize(5.0)

but of course that may not help in the Ruby API world?

thomthom

I don't know if/how one would issue that in SU Ruby :/.

What is more: I closed SU and renamed my plugins folder - testing only my own script. The points where drawn as pixels as I saw at the office. When I restored the plugin folder I still saw the points drawn as single pixels!

So there must have been some odd glitch. I did have that SU session open for a few days where I just put my computer in sleep mode. Maybe some other plugins changed the point size - when I ran it. Or some external glitch.... Really don't understand how it occurred. But I do want the effect of that glitch.