I still can't believe I can't get this.
I'm trying to write a 3d track designer app and I'm stuck on this really simple thing. I can't see the wood for the trees.
Imagine your looking at a 2d grid where you can define anchor points. I've got a routine that will take the anchor points and create a spline line with calculated intermediate points to create a smooth curved track line.
The anchor points and intermediate co-ordinates are stored in a array draw_point(1000,2).
Here is a stripped down code bit for defining the anchor points.
If the first point is drawn a the centre of the screen. The second point a few inches directly above it and the third point directly to the right of it you should see a right angled shape but the little line formed at point 2 is pointing directly at point 3 and rotated thru 90 degrees.
Ideally, I would like this small line to be rotated to form a angle exactly half of the diffence between the two lines so I can attach vertex information to the end points and create a track.
How do I go about doing this. I'm really stuck.
What I get is this:-
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When I really what this
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I'm trying to write a 3d track designer app and I'm stuck on this really simple thing. I can't see the wood for the trees.
Imagine your looking at a 2d grid where you can define anchor points. I've got a routine that will take the anchor points and create a spline line with calculated intermediate points to create a smooth curved track line.
The anchor points and intermediate co-ordinates are stored in a array draw_point(1000,2).
Here is a stripped down code bit for defining the anchor points.
Open in online IDEGraphics3D 800,600,16,2 SetBuffer BackBuffer() camPiv = CreatePivot() camera = CreateCamera(camPiv) PositionEntity(camera, 0,0,-1000) CameraRange camera,1,9000 light=CreateLight() RotateEntity light,100,100,1000 ;set up a non visible cursor entity test_sphere=CreateSphere () ScaleMesh test_sphere,20,20,20 EntityColor test_sphere, 255,100,100 EntityAlpha test_sphere, 0.4 ;*** Transparece CreateCube() Global pivot=CreatePivot() Global pivot2=CreatePivot() Global campitch#,camyaw#,timer cam_z= -1000 ;make_grid() Dim pos(100,2) ;storage for the hand drawn lines. Dim angles(100,2) ;Make_grid() V_Pos = 0; the first start to array ; Mainloop While Not KeyDown(1) Cls ; Clear screen ;half of screen dimensions needed w=GraphicsWidth() : h=GraphicsHeight() ;Mouse Related bits;positions x#=MouseX() : y#=MouseY() xs=MouseXSpeed() : ys=MouseYSpeed() ; see how far the mouse has been moved If MouseHit (1) Then PositionEntity test_sphere,(x-w)/w*2,-(y-h)/w*2,2 PositionEntityFrom2D (camera, test_sphere, x, y, 0, 1) pos(V_Pos, 0) = EntityX (test_sphere) pos(V_Pos, 1) = EntityY (test_sphere) pos(V_Pos, 2) = EntityZ (test_sphere) V_Pos=V_Pos + 1 EndIf ;move the screen If mouse down If MouseDown (3) Then xview = xview + xs * cam_z/300 yview = yview - ys * cam_z/200 End If cam_z = cam_z+MouseZSpeed()*80; move the depth and ramp with distance PositionEntity camera,xview,yview,cam_z RenderWorld If V_Pos > 1 Then For loop = 1 To V_Pos-1 Line3d(pos(loop-1, 0),pos(loop-1, 1),0,pos(loop, 0),pos(loop, 1),0, camera) Next EndIf For loop = 1 To V_Pos-1 PositionEntity pivot, pos(loop-1, 0),pos(loop-1, 1),0 PositionEntity pivot2,pos(loop, 0),pos(loop, 1),0 x1 = EntityX (pivot) y1 = EntityY (pivot) PointEntity pivot,pivot2,0 TFormPoint 0,-30,0,pivot,0 x1 = TFormedX() y1 = TFormedY() z1 = TFormedZ() TFormPoint 0,30,0,pivot,0 x2 = TFormedX() y2 = TFormedY() z2 = TFormedZ() Line3d(x1,y1,z1,x2,y2,z2, camera) Next Flip ; Flip backbuffer to frontbuffer Wend End Function PositionEntityFrom2D (usecam, entity, x2d#, y2d#, positionGlobal = 0, camZoom# = 1) gw = GraphicsWidth () gh = GraphicsHeight () x# = -((gw / 2) - x2d) y# = (gh / 2) - y2d parent = GetParent (entity) EntityParent entity, usecam z3d# = Abs (EntityZ (entity)) div# = (gw / (2 / camzoom)) / z3d PositionEntity entity, x / div, y / div, z3d, positionGlobal EntityParent entity, parent End Function Function Line3d(x0#,y0#,z0#,x1#,y1#,z1#, camera) CameraProject (camera,x0,y0,z0) px0#=ProjectedX# ( ) py0#=ProjectedY# ( ) pz0#=ProjectedZ# ( ) CameraProject (camera,x1,y1,z1) If ProjectedZ#( ) >0 And pz0>0 Then Line px0,py0,ProjectedX# ( ) ,ProjectedY# ( ) End Function ;================================================================================= ;Point Entity at x,y,z ;================================================================================= Function Point_Entity(entity,x,y,z) xdiff = EntityX(entity)-x ydiff = EntityY(entity)-y zdiff = EntityZ(entity)-z dist=Sqr((xdiff*xdiff)+(zdiff*zdiff)) pitch = ATan2(ydiff,dist) yaw = ATan2(xdiff,-zdiff) RotateEntity entity,pitch,yaw,0 End Function
If the first point is drawn a the centre of the screen. The second point a few inches directly above it and the third point directly to the right of it you should see a right angled shape but the little line formed at point 2 is pointing directly at point 3 and rotated thru 90 degrees.
Ideally, I would like this small line to be rotated to form a angle exactly half of the diffence between the two lines so I can attach vertex information to the end points and create a track.
How do I go about doing this. I'm really stuck.
What I get is this:-
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|
|
|
When I really what this
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