2.3 DrawLine

[Chris Paulson]

My function: -

void tdDraw( TCamera cam, TVec3 s, TVec3 e )
{
TVec3 p1;
TVec3 p2;
p1 = CameraUnproject( cam, s );
p2 = CameraUnproject( cam, e );

if (p1.Z < 0 || p2.Z < 0) return;

DrawLine( p1.X, p1.Y, p2.X-p1.X, p2.Y-p1.Y );
}

 

 

Seems not to work correctly anymore, one end of the line seems to be in the correct place but the other is always top left.

 

Has it changed?

[TylerH]

Yes, it now takes the absolute coordinates X1 Y1 and X2 Y2, each pair is its own endpoint.

[Josh]

It's the same in 2.28.

[Canardia]

If you are using C++, you might consider using gamelib's Line function instead, as it's about 10 times faster than LE's DrawLine:

inline void Color(double r, double g, double b, double a)
{
glColor4f(r,g,b,a);
}

inline void Line(int x, int y, int w, int h)
{
glBegin(GL_LINES);
glVertex2i(x,y);
if(0==w)w=1;
glVertex2i(x+w,y+h);
glEnd();
}

[Chris Paulson]

Yes, it now takes the absolute coordinates X1 Y1 and X2 Y2, each pair is its own endpoint.

 

Thanks that did the trick.

 

Thnaks Lumooja, I'll convert over.

[Josh]

The speed of drawing a line is not a bottleneck. The command you wrote is the same thing the engine does internally.

[Canardia]

Yeah, it's just a simple direct mode OpenGL command after all, but when it's called often, like in speed tests, the fact that the DLL call has to go through many more instructions (BlitzMax GC, C headers) than a C++ inline function (which is stored directly into the loop, not even calling the function internally (thus avoiding the stack, which is slow)), sums up in the speed difference.

 

Sure it's not a bottleneck, as nobody would call thousands of DrawLines per frame