Code archives/3D Graphics - Effects/Simple shadows
This code has been declared by its author to be Public Domain code.
Download source code
| This is a simple shadow system I made for fun. It's not that fast, and alpha shadows don't work properly.. but you might learn something from this. Pic:  |
Graphics3D 800,600,0,2 SetBuffer BackBuffer() Global Cam = CreateCamera() MoveEntity Cam,0,5,-2 NewObject = GetObject() ;Position our entity MoveEntity NewObject,0,2.5,0 ;White plane Plane = CreatePlane() EntityColor Plane,255,255,255 MoveEntity Plane,0,-0.01,0 ;Create light Light = CreateSphere(5) Spot = CreateLight(2,Light) ScaleEntity Light,0.1,0.1,0.1 EntityColor Light,255,255,0 Repeat ;Camera movement If KeyDown(200) Then MoveEntity Cam,0,0,1 If KeyDown(208) Then MoveEntity Cam,0,0,-1 If KeyDown(203) Then MoveEntity Cam,-1,0,0 If KeyDown(205) Then MoveEntity Cam,1,0,0 ;Shadow object must be created and destroyed every frame Shadow = CreateMesh() EntityAlpha Shadow,1 ;There is sadly a bug with alpha shadows.. Didn't figure out a proper solution to this one ;You could use a camera, but would be a major slowdown ; EntityColor Shadow,0,0,0 ;Light movement GY# = 7+Sin(MilliSecs()/10)*0.5 GX# = Cos(MilliSecs()/10)*3 ;Draw shadow DrawShadow(NewObject,GX#,GY#,GZ#,Shadow) PositionEntity Light,GX#,GY#,GZ# ;FPS FPSC=FPSC+1 If MilliSecs()>FPSTimer+999 Then FPSTimer = MilliSecs() FPS=FPSC FPSC=0 EndIf RenderWorld Text 0,0,"FPS: " + FPS ;Text 0,20,"Trisrendered: " + TrisRendered() Flip 0 ;Destroy shadow FreeEntity Shadow Until KeyHit(1) Function DrawShadow(Entity,SX#,SY#,SZ#,Shadow) ;This works by looping through all triangles, then calculating a line for each vertex to ground (y=0) EX#=EntityX#(Entity,1) EY#=EntityY#(Entity,1) EZ#=EntityZ#(Entity,1) ShadowSurface = CreateSurface(Shadow) Surfaces=CountSurfaces(Entity) For s=1 To Surfaces Surface = GetSurface(Entity,s) Triangles=CountTriangles(Surface)-1 For t=0 To Triangles v1 = TriangleVertex(Surface,t,0) v2 = TriangleVertex(Surface,t,1) v3 = TriangleVertex(Surface,t,2) v1X# = VertexX#(Surface,v1)+EX# v1Y# = VertexY#(Surface,v1)+EY# v1Z# = VertexZ#(Surface,v1)+EZ# K#=-SY#/(SY#-v1Y#) v1XR# = SX# + (SX#-v1X#)*K# v1ZR# = SZ# + (SZ#-v1Z#)*K# v2X# = VertexX#(Surface,v2)+EX# v2Y# = VertexY#(Surface,v2)+EY# v2Z# = VertexZ#(Surface,v2)+EZ# K#=-SY#/(SY#-v2Y#) v2XR# = SX# + (SX#-v2X#)*K# v2ZR# = SZ# + (SZ#-v2Z#)*K# v3X# = VertexX#(Surface,v3)+EX# v3Y# = VertexY#(Surface,v3)+EY# v3Z# = VertexZ#(Surface,v3)+EZ# K#=-SY#/(SY#-v3Y#) v3XR# = SX# + (SX#-v3X#)*K# v3ZR# = SZ# + (SZ#-v3Z#)*K# ;Backface culling works by calculating a camera vector and a surface normal ;If the dot product is > 0 then draw ;Camera vector CX#=SX#-(v1X#+v2X#+v3X#)*0.33333 CY#=SY#-(v1Y#+v2Y#+v3Y#)*0.33333 CZ#=SZ#-(v1Z#+v2Z#+v3Z#)*0.33333 ;Surface normal, create 2 vectors and then create vector W from their cross product UX# = V2X#-V1X# UY# = V2Y#-V1Y# UZ# = V2Z#-V1Z# VX# = V3X#-V1X# VY# = V3Y#-V1Y# VZ# = V3Z#-V1Z# WX# = UY#*VZ#-UZ#*VY# WY# = -(UX#*VZ#-UZ#*VX#) WZ# = UX#*VY#-UY#*VX# ;Add triangle If (SY#>v1Y#) And (SY#>v2Y#) And (SY#>v3Y#) And (CX#*WX#+CY#*WY#+CZ#*WZ#)>0.0 Then AddTriangle(ShadowSurface,AddVertex(ShadowSurface,v1XR#,0,v1ZR#),AddVertex(ShadowSurface,v2XR#,0,v2ZR#),AddVertex(ShadowSurface,v3XR#,0,v3ZR#)) EndIf Next Next End Function ;Create a test object Function GetObject() NewObject = CreateMesh() Cube = CreateCube() ScaleMesh Cube,0.6,2.5,0.6 PositionMesh Cube,-3,0,3 AddMesh Cube,NewObject PositionMesh Cube,6,0,0 AddMesh Cube,NewObject PositionMesh Cube,-6,0,-6 AddMesh Cube,NewObject PositionMesh Cube,6,0,0 AddMesh Cube,NewObject Sphere = CreateSphere(16) PositionMesh Sphere,-3,2.5,3 AddMesh Sphere,NewObject PositionMesh Sphere,6,0,0 AddMesh Sphere,NewObject PositionMesh Sphere,-6,0,-6 AddMesh Sphere,NewObject PositionMesh Sphere,6,0,0 AddMesh Sphere,NewObject FreeEntity Cube FreeEntity Sphere EntityColor NewObject,0,200,0 Return NewObject End Function |