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Shading Terrains?

Blitz3D Forums/Blitz3D Programming/Shading Terrains?

amitjf(Posted 2008) [#1]
Hey,
I'm still workin on the "visible polys on terrain" project, but i figured out that the function that Stevie if im not wrong, gave me, is not good enough for my needs. So someone there said "why won't you put a spotlight and shade the not visible areas?"

So what i need is a sample of how if at all possible, i can use devils shadow system in order to shadow the not visible areas on the same mesh(i mean the receiver and the caster would be the same mesh so hills would cast on the ground. like creating dynamically a lightmap for the terrain by a given position of the spotlight). the terrain mesh is about 25k polys i think( its not the same mesh all the time), so i might need a function to divide the mesh to blocks.
Thanks in advance


amitjf(Posted 2008) [#2]
Are we going to break a record? nevermind.
well here is the topic i was talking about:
http://blitzbasic.com/Community/posts.php?topic=77338#865829


Stevie G(Posted 2008) [#3]
Like I said - post or e-mail your code and explain explicitly what you want ( a picture would be a help too ) and I ( and others ) should be able to help.


amitjf(Posted 2008) [#4]
do you want the whole code? or just a part of it?

EDIT:
nevermind. I didn't want to do that but youve asked for it(muhahahaha), here is my very not organized code:


So my need is a function that would be used like that:
spotlight1=createlight(); I guess
positionentity spotlight1,entityx(camera_pivot),entity(camera_pivot),entityz(camera_pivot)
if keyhit(key_r)
shadeterrainacordingtospotlight(terrain1,spotlight1)
end if

or another option is
if keyhit(key_r)
shadeterrainacordingtoposition(terrain1,x,y,z)
end if

so what will come out will be like the function you gave me using line pick on last topic, but it should be much more accurated(the problem with tha function you gave is that it send a linepick to the center of the triangle, but my need is like to send it to every single point on the triangle and even if one is visible then color the triangle(and some why it wasnt accurated and colored some triangle wrong)


Stevie G(Posted 2008) [#5]
When I said post the code - I meant something which I can run without other include files / media etc..

btw. Native spotlights are going to light hidden poly's so this isn't what you want.

The function I gave you could be easily amended to do a check on all 3 vertices of the triangle.

Function TRIScolor( Mesh , Viewer )

	;get viewers direction normal
	TFormNormal 0,0,1,Viewer, 0
	CamNx# = TFormedX()
	CamNy# = TFormedY()
	CamNz# = TFormedZ()

	For su = 1 To CountSurfaces( Mesh )
		s = GetSurface( Mesh , su )
		For t = 0 To CountTriangles( s ) - 1
		
			;get vertices in triangle - normals should be same on each
			v0 = TriangleVertex( s, t, 0 )
			v1 = TriangleVertex( s, t, 1 )
			v2 = TriangleVertex( s, t, 2 )
			
			;get triangle normal in world space coords
			TFormVector VertexNX( s, v0 ), VertexNY( s, v0 ) , VertexNZ( s, v0 ) , Mesh , 0
			TriNx# = TFormedX() 
			TriNy# = TFormedY() 
			TriNz# = TFormedZ() 			 
			
			;compute dot product of camera normal and tri normal
			CdotN# = CamNx * TriNx + CamNY * TriNy + CamNz * TriNz
			
			;default rgb to white
			tR = 255
			tG = 255
			tB = 255
			
			If CdotN <= .000001 Then

				;this triangle is facing camera so check whether any of the vertices are obscured
				For v = v0 To v2
					;get vertex position in world space coords
					TFormPoint VertexX( s, v ) , VertexY( s, v ) , VertexZ( s, v ), mesh, 0
					;get direction vector from vertex position to viewer
					Dx# = TFormedX() - EntityX( viewer, 1 )
					Dy# = TFormedY() - EntityY( viewer, 1 )
					Dz# = TFormedZ() - EntityZ( viewer, 1 )
					;do a linepick from the viewer to the vertex
					Picked = LinePick( EntityX( viewer , 1 ) , EntityY( viewer , 1 ) , EntityZ( viewer , 1 ) , Dx, Dy , Dz )
					;the linepick hit something so this tri is obscured
					If PickedTime() < 1.0
						tR = 255
						tG = 0
						tB = 0
						Exit
					EndIf
				Next					

			EndIf
	
			;color this triangle
			For v = v0 To v2
				VertexColor s, v, tR, tG , tB
			Next

		Next
	Next
	
End Function


Does this work for you?

Stevie


amitjf(Posted 2008) [#6]
I'm pretty noob in blitz but not that i cant think of doing that for the 3 vertexes. even though when ive done that, it wasn't really accurate(it was even worse when using all the 3 vertexes) and colored wrongly.