2d line drawing with width

[mansie]

Not sure if this will help anyone - but the 2d line draw function in 6.5 has no width change parameter, which makes it a bit limited  . So, I've written a small procedure which takes 5 parameters - fromX, fromY, toX, toY,widthofline. And draws a nice thick line with rounded ends!

It took me a little while to work out the trig (I'm a little rusty) so hopefully it'll save someone else having to do the same!

Private Sub myline(x1 As Single, y1 As Single, x2 As Single, y2 As Single,w As Single)

Dim m As Single
Dim n As Single
Dim a As Single
Dim x As Single
Dim y As Single
Dim l As Single

'circle at the intersection for smoothness... and single point 'lines'
screen2D.Draw_FilledCircle x1, y1, w, 20, RGBA(1, 1, 1, 1)


' base line
x = x2 - x1
'height
y = y2 - y1

' Work out the line length
l = Sqr((x * x) + (y * y))
'check for zero line length
If l = 0 Then Exit Sub



'angle
 a = math.ACos(x / l) - 90
 
 If y2 >= y1 Then
  m = w * (Sin(math.Deg2Rad(a - 90)))
  n = w * -(Cos(math.Deg2Rad(a - 90)))
 End If
 
 If y2 < y1 Then
  m = w * (Sin(math.Deg2Rad(a + 90)))
  n = w * (Cos(math.Deg2Rad(a + 90)))
 End If
 

'put in the first triangle
screen2D.Draw_FilledTriangle (x1 + m), (y1 + n), (x2 - m), (y2 - n), (x2 + m), (y2 + n), RGBA(1, 1, 1, 1)
'then the second to make a filled rectangle...
screen2D.Draw_FilledTriangle (x1 + m), (y1 + n), (x1 - m), (y1 - n), (x2 - m), (y2 - n), RGBA(1, 1, 1, 1)

'and round off the end
screen2D.Draw_FilledCircle x2, y2, w, 20, RGBA(1, 1, 1, 1)



End Sub


mansie

[AriusEso]

lol

A line with a thicker width than 1 pixel is no longer a line. It is a rect. TV has functions for this already, rounded ones too.

[mansie]

Really? You can you draw a rectangle from (say) 100,100 to 300,200 with any 'width' and with rounded ends?

What is this function - I cant find it, but if it exists - looks like I've done all this for nothing!

[AriusEso]

Aha, I checked the header. It doesn't have rounded. But you can use this for a thicker line:

void Draw_FilledBox(float x1, float y1, float x2, float y2, int color1 = -1, int color2 = -2, int color3 = -2, int color4 = -2);

After all, a thick line is simply a filled quad/box.

[WEst]

Aha, I checked the header. It doesn't have rounded. But you can use this for a thicker line:

void Draw_FilledBox(float x1, float y1, float x2, float y2, int color1 = -1, int color2 = -2, int color3 = -2, int color4 = -2);

After all, a thick line is simply a filled quad/box.

But thats not a line with width, its a rectangle in screenspace coordinates, a line with width is imho an aligned rectangle with its width (normally smaller than length) being normal to its direction.

[AriusEso]

But thats not a line with width, its a rectangle in screenspace coordinates, a line with width is imho an aligned rectangle with its width (normally smaller than length) being normal to its direction.

Depends whether you're talking a 3D line or a 2D line, no? Unless I'm misunderstanding what you mean.

In this case I think he means a 2D line.

[mansie]

Let me explain....

If I need to draw a thick line, of a certain thickness, from one screen coordinate to another, in 2d, then drawing a filled rectangle doesn't really do it. Hence my routine.

Mansie

[Raine]

In layman terms, you wanna draw a line to point x1y1 to point x2y2 no matter what - this excludes drawing a rect instead of a line, since it would only work if the coords make sure the borders are parallel to the screen axis. You can't draw a rotated line with a the tv draw rect function.

Is this correct? :S

[mansie]

Thats correct. It's what my procedure (above) does.

I'm using it as part of a freehand drawing application in which the coordinates come from the mouse x,y position, and it draws a freehand line, on a 2d background, with each segment of the line connected to the end of the previous line, to create a continuous wavy line.



 

[AriusEso]

Ahh, I guess I was mistaken then. It is like 4pm and I still haven't been to bed yet, so forgive me .

[jviper]

There is a draw custom polygon.