how to draw a rounded filled rect

BlitzMax Forums/BlitzMax Programming/how to draw a rounded filled rect

ziggy

(Posted 2006) [#1]

I would like to draw a rounded filled rect, without making circles and boxes (becouse if I make circles and boxes, the result si not alpha-compatible.

Any suggestion on how to do that?

TartanTangerine (was Indiepath)

(Posted 2006) [#2]

When BMAX draws a shape it's actually creating a surface from polygons, becuase the polygonal surface is not textured, and BMAX does not allow edge antialiasing, you will get pixelated edges.

I suggest you try using textured polygons of just use a simple image.

AlexO

(Posted 2006) [#3]

If you wanted it as a simple DrawRoundRect() function you could possibly make a series of images put together on each draw call. like a top left round corner, top right, middle, etc. that way you can scale the center image without having skewed corners.

tonyg

(Posted 2006) [#4]

didn't you ask for this before
<edit> Oopps just saw the bit about circles/rects.
<edit> Can you still use them then grab them...

Function DrawRoundRect:TImage(x:Int, y:Int, width:Int, height:Int, radius:Int)
	DrawOval(x, y, radius, radius)
	DrawOval(x + (width - (radius)), y, radius, radius)
	DrawOval(x, y + (height - (radius)), radius, radius)
	DrawOval(x + (width - (radius)), y + (height - (radius)), radius, radius)
	DrawRect(x + (radius / 2), y, width - radius, height)
	DrawRect(x, y + (radius / 2), width, height - radius)
	Return LoadImage(GrabPixmap(100,100,100,100),FILTEREDIMAGE|MIPMAPPEDIMAGE)
End Function
Graphics 640,480
'drawroundrect(100,100,100,100,10)
'image:TImage=LoadImage(GrabPixmap(100,100,100,100),FILTEREDIMAGE|MIPMAPPEDIMAGE)
image:TIMAGE=drawroundrect(100,100,100,100,10)
Cls
DrawImage image,0,0
Flip
WaitKey()

ziggy

(Posted 2006) [#5]

@Tonyg: I'll try it this way, but just another question: How can I make anti-aliased borders? (I think in OpenGL there's a simple flag, but in DX...)

tonyg

(Posted 2006) [#6]

const D3DRS_EDGEANTIALIAS=40
PrimaryDevice.device.SetRenderState D3DRS_EDGEANTIALIAS,True
More here

ziggy

(Posted 2006) [#7]

@tonig: It's not working, I can't preserve the alpha channel of the corners... Any other suggestion?

tonyg

(Posted 2006) [#8]

Indie's render-to-texture would be able to do it.

Grey Alien

(Posted 2006) [#9]

Indie's example in TonyG's link doesn't work for me either. I just get a jagged line:

Const D3DRS_EDGEANTIALIAS=40

Graphics 640,480,0,60
SetBlend(ALPHABLEND)
PrimaryDevice.device.SetRenderState D3DRS_EDGEANTIALIAS,True
DrawLine 10,10,100,600
Flip
WaitKey()

tonyg

(Posted 2006) [#10]

Wasn't that believed to be a graphics card specific issue similar to the antialias issue on B3D?

ImaginaryHuman

(Posted 2006) [#11]

You could just do custom OpenGL and create a triangle strip which runs around the edge of a rectangle - when it gets to a corner it attaches the inside edge to the corner and curves around it.