Textured polygon in D3D

BlitzMax Forums/BlitzMax Programming/Textured polygon in D3D

Ion	(Posted 2008) [#1]

So how do you draw a textured polygon in direct3d?

tonyg

(Posted 2008) [#2]

TexturedPoly
There is a lot more discussion and some more source code on the forums.

Ion	(Posted 2008) [#3]

Golden! This works great! One question tough...
I'm using these functions to calculate the UV coordinates from the vertices..

	Function GetU:Float(x:Float,y:Float)
		Return x/Sqr(x*x + y*y)
	EndFunction
	
	Function GetV:Float(x:Float, y:Float)
		Return y/Sqr(x*x + y*y)
	EndFunction

However, the texture is stretched when the polygon is aligned in certain ways. Is there a better way to calculate this?

xMicky

(Posted 2008) [#4]

U, V are the texture coordinates running from 0 to 1 .
X,Y are the geometrical coordinates running from anyvalue1 to anyvalue2.
U,V and X,Y are unrelated to each other until you define a relation: x0 equals 0, x1 equals 1.

Also U,V and X,Y are each orthogonal and linear independent from another so you don't have to invoke V and/or Y if you want to calculate U and vice versa.

Therefore I would code for Transformation (with wrapping) :

Function GetU:Float(x;Int, x0:Int, x1:Int)

 Local DistX:Float =Abs(x -x0) Mod Float(x1 -x0)
 If x < x0 then
   DistX :+(x1 -x0)
 End If
 Return DistX /Float(x1- x0)

End Function

Ion	(Posted 2008) [#5]

thanks xMicky, works great!