JV ODE _ Newbie Question

Blitz3D Forums/Blitz3D Userlibs/JV ODE _ Newbie Question

Al Meyer (Posted 2008) [#1]

I know that is not very JV ODE related, but i´m using one of their demos to build a little app with physics. I´m a newbie of Blitz3D and getting some trouble to setup my things up. In demo CarDemo-Trimesh-Capsule, the car is always in center of screen. I need the car to be position almost at botton of the screen. here an image what i pretend Thanks in advance

VIP3R (Posted 2008) [#2]

Look at the Blitz3D docs for 'pivots'. You need to create a pivot and parent it to 'CMesh' (the car body), then offset the pivot on the y-axis. ; # Needs to be placed after the 'Create car body' code Global YourPivot=CreatePivot(CMesh) PositionEntity YourPivot,0,5,0 Next, point the camera at the pivot instead of the car body in the UpdateCam() function of the demo... Change... PointEntity Camera,CMesh to... PointEntity Camera,YourPivot

Al Meyer (Posted 2008) [#3]

Thank You very much, Vip3r. It gives me a weird camera move, but it point me to a correct solution. Thanks a lot

VIP3R (Posted 2008) [#4]

Oops, the weird camera movement is because the camera pivot needs changing too... Make sure you create 'YourPivot' before the camera setup code, then... Change... Global CameraPivot=CreatePivot(CMesh) to... Global CameraPivot=CreatePivot(YourPivot)

Al Meyer (Posted 2008) [#5]

Hi, I did it and it is broken the visualization.

VIP3R (Posted 2008) [#6]

Hmm, for some reason I thought you wanted the car slightly to the right before, I must have mis-read it. I've updated the position code above to reflect this. Here's a car demo showing the new camera position... ; ################################################################################################### ; # JV-ODE Car Demo # ; # Code by Jim Williams (VIP3R) # ; # Devious Codeworks - Copyright © 2007 # ; ################################################################################################### AppTitle "JV-ODE Car Demo" Include "JV-ODE.bb" Graphics3D 800,600,0,2 Global CMass#=200 ; ### Car Mass Global WMass#=14 ; ### Wheel Mass Global WorldERP#=1 ; ### World Error Correction Global WorldFriction#=70 ; ### World Friction Global Torque#=24 ; ### Joint Torque Global SuspensionHS#=0.01 ; ### Suspension Hardness/Softness (Higher=Softer - Lower=Harder) Global Force#=0 Global Steer#=0 Global Car Global CGeom Global CMesh Global CarStartY=20 Dim Wheel(4) Dim WGeom(4) Dim Joint(4) Type ODEGeom Field body Field geom Field mesh End Type ; ################################################################################################### ; ### Setup ODE Global World=dWorldCreate() Global Space=dHashSpaceCreate(0) Global ContactGroup=dJointGroupCreate(0) dWorldSetAutoDisableFlag(World,1) dWorldSetGravity(World,0,-0.98,0) dWorldSetERP(World,WorldERP) dContactSetMode(dContactSlip1) dContactSetMu(WorldFriction) ; ### Create car body ode.ODEGeom=New ODEGeom ode\body=dBodyCreate(World) Car=ode\body dBodySetRotation(ode\body,0,0,0) dBodySetPosition(ode\body,0,CarStartY,0) mass=dMassCreate() dMassSetBoxTotal(mass,CMass,3,1,4) dBodySetMass(ode\body,mass) dMassDestroy(mass) ode\geom=dCreateBox(Space,3,1,4) CGeom=ode\geom dGeomSetBody(ode\geom,ode\body) ode\mesh=CreateCube() CMesh=ode\mesh ScaleMesh ode\mesh,1.5,0.5,2 RotateMesh ode\mesh,0,0,0 PositionMesh ode\mesh,0,0,0 EntityColor ode\mesh,40,80,255 EntityAlpha ode\mesh,1 ; ### Create wheels For count=1 To 4 ode.ODEGeom=New ODEGeom ode\body=dBodyCreate(World) Wheel(count)=ode\body dBodySetRotation(ode\body,0,0,0) dBodySetPosition(ode\body,0,0,0) mass=dMassCreate() dMassSetSphereTotal(mass,WMass,0.7) dBodySetMass(ode\body,mass) dMassDestroy(mass) ode\geom=dCreateSphere(Space,0.7) WGeom(count)=ode\geom dGeomSetBody(ode\geom,ode\body) ode\mesh=CreateCylinder(8) ScaleMesh ode\mesh,0.7,0.25,0.7 RotateMesh ode\mesh,0,0,90 PositionMesh ode\mesh,0,0,0 EntityColor ode\mesh,255,255,255 Next dBodySetPosition(Wheel(1),-2,CarStartY-0.5,+2) dBodySetPosition(Wheel(2),+2,CarStartY-0.5,+2) dBodySetPosition(Wheel(3),-2,CarStartY-0.5,-2) dBodySetPosition(Wheel(4),+2,CarStartY-0.5,-2) ; ### Create some objects SeedRnd MilliSecs() For spheres=1 To 20 ode.ODEGeom=New ODEGeom ode\body=dBodyCreate(World) dBodySetRotation(ode\body,0,0,0) dBodySetPosition(ode\body,Rnd(-100,100),30,Rnd(-100,100)) ode\geom=dCreateSphere(Space,4) dGeomSetBody(ode\geom,ode\body) ode\mesh=CreateSphere() ScaleMesh ode\mesh,4,4,4 RotateMesh ode\mesh,0,0,0 PositionMesh ode\mesh,0,0,0 EntityColor ode\mesh,Rnd(255),Rnd(255),Rnd(255) EntityAlpha ode\mesh,1 EntityShininess ode\mesh,0.7 Next For capsules=1 To 20 ode.ODEGeom=New ODEGeom ode\body=dBodyCreate(World) dBodySetRotation(ode\body,90,0,0) dBodySetPosition(ode\body,Rnd(-100,100),30,Rnd(-100,100)) ode\geom=dCreateCapsule(Space,1,8) dGeomSetBody(ode\geom,ode\body) ode\mesh=CreateCylinder(8) ScaleMesh ode\mesh,1,5,1 RotateMesh ode\mesh,90,0,0 ; <<< Mesh X-Axis must be rotated 90 degrees to fix cylinder alignment PositionMesh ode\mesh,0,0,0 EntityColor ode\mesh,Rnd(255),Rnd(255),Rnd(255) EntityAlpha ode\mesh,1 EntityShininess ode\mesh,0.7 Next ; ### Create light Global Light=CreateLight() RotateEntity Light,45,-90,0 LightColor Light,255,255,255 AmbientLight 130,130,130 ; ### Create camera Global OffsetPivot=CreatePivot(CMesh) PositionEntity OffsetPivot,0,5,0 Global CameraPivot=CreatePivot(OffsetPivot) PositionEntity CameraPivot,0,2,-7 Global Camera=CreateCamera() CameraClsColor Camera,0,0,0 CameraRange Camera,1,1000 ; ### Create plane dCreatePlane(Space,0,1,0,0) Plane=CreatePlane() EntityAlpha Plane,0.8 PlaneTexture=CreateTexture(128,128,9) ClsColor 0,200,80 Cls Color 255,255,255 Rect 0,0,64,64,1 Rect 64,64,64,64,1 CopyRect 0,0,128,128,0,0,BackBuffer(),TextureBuffer(PlaneTexture) ScaleTexture PlaneTexture,20,20 EntityTexture Plane,PlaneTexture,0,0 Mirror=CreateMirror() ; ################################################################################################### ; ### BLITZ STATIC OBJECT (White) blitzobject=CreateCube() ScaleMesh blitzobject,1,4,20 RotateMesh blitzobject,-10,8,4 PositionMesh blitzobject,10,5,40 EntityColor blitzobject,255,255,255 EntityAlpha blitzobject,1 ; ### ODE STATIC OBJECT (Blue) ode.ODEGeom=New ODEGeom ode\geom=dCreateBox(Space,2,8,40) dGeomSetRotation(ode\geom,-10,8,4) dGeomSetPosition(ode\geom,20,5,40) ode\mesh=CreateCube() ScaleMesh ode\mesh,1,4,20 RotateMesh ode\mesh,0,0,0 PositionMesh ode\mesh,0,0,0 EntityColor ode\mesh,0,100,200 EntityAlpha ode\mesh,1 ; ### ODE STATIC OBJECT (Red) ode.ODEGeom=New ODEGeom ode\geom=dCreateBox(Space,18,0.2,40) dGeomSetRotation(ode\geom,-14,0,0) dGeomSetPosition(ode\geom,-20,4.9,40) ode\mesh=CreateCube() ScaleMesh ode\mesh,9,0.1,20 RotateMesh ode\mesh,0,0,0 PositionMesh ode\mesh,0,0,0 EntityColor ode\mesh,200,0,100 EntityAlpha ode\mesh,1 ; ################################################################################################### SetupCar() While Not KeyHit(1) UpdateKeys() PTime=MilliSecs() UpdateCar() UpdateGeoms() dSpaceCollide(Space,World,ContactGroup) dWorldQuickStep(World,0.1) dJointGroupEmpty(ContactGroup) PhysicsTime#=MilliSecs()-PTime UpdateCam() UpdateWorld RenderWorld Text 0,0,"JV-ODE Version "+dGetVersion() Text 0,15,"Physics Time:"+PhysicsTime Text 0,50,"Force:"+Force Text 0,65,"Torque:"+Torque Text 640,0,"A - Accelerate" Text 640,15,"Z - Brake/Reverse" Text 640,30,"Arrows - Steering" Text 640,45,"Space - Reset Car" Flip Wend dJointGroupDestroy(ContactGroup) dSpaceDestroy(Space) dWorldDestroy(World) dCloseODE() End ; ################################################################################################### Function SetupCar() For count=1 To 4 Joint(count)=dJointCreateHinge2(World,0) dJointAttach(Joint(count),Car,Wheel(count)) dJointSetHinge2Anchor(Joint(count),dBodyGetPositionX(Wheel(count)),dBodyGetPositionY(Wheel(count)),dBodyGetPositionZ(Wheel(count))) dJointSetHinge2Axis1(Joint(count),0,1,0) dJointSetHinge2Axis2(Joint(count),-1,0,0) dJointSetHinge2Param(Joint(count),dParamSuspensionERP,0.8) dJointSetHinge2Param(Joint(count),dParamSuspensionCFM,SuspensionHS) If count>2 dJointSetHinge2Param(Joint(count),dParamLoStop,0) dJointSetHinge2Param(Joint(count),dParamHiStop,0) End If Next Force=0 End Function ; ################################################################################################### Function UpdateKeys() If KeyDown(30)=1 Force=Force+0.08 If Force>30 Then Force=30 End If If KeyDown(44)=1 Force=Force-0.1 If Force<-10 Then Force=-10 If Force>0 Then Force=Force*0.97 End If If KeyDown(30)=0 And KeyDown(44)=0 Then Force=Force*0.99 If KeyDown(203)=1 Or KeyDown(205)=1 If KeyDown(203)=1 Steer=0.5 Else Steer=-0.5 End If Else Steer=0 End If If KeyHit(57)=1 Force=0 dBodySetRotation(Car,dGeomGetPitch#(CGeom),dGeomGetYaw#(CGeom),0) End If End Function ; ################################################################################################### Function UpdateCar() For count=1 To 4 dBodyEnable(Wheel(count)) Next dBodyEnable(Car) For count=1 To 4 dJointSetHinge2Param(Joint(count),dParamVel2,Force) dJointSetHinge2Param(Joint(count),dParamFMax2,Torque) Next For count=1 To 2 angle#=Steer-dJointGetHinge2Angle1(Joint(count)) dJointSetHinge2Param(Joint(count),dParamVel,angle) dJointSetHinge2Param(Joint(count),dParamFMax,400) Next End Function ; ################################################################################################### Function UpdateCam() PositionEntity CameraPivot,0,-2,-12 camx#=EntityX(CameraPivot,1)-EntityX(Camera) camy#=EntityY(CameraPivot,1)-EntityY(Camera) camz#=EntityZ(CameraPivot,1)-EntityZ(Camera) TranslateEntity Camera,camx*0.5,camy*0.5,camz*0.5 PointEntity Camera,OffsetPivot End Function ; ################################################################################################### Function UpdateGeoms() For ode.ODEGeom=Each ODEGeom RotateEntity ode\mesh,dGeomGetPitch#(ode\geom),dGeomGetYaw#(ode\geom),dGeomGetRoll#(ode\geom) PositionEntity ode\mesh,dGeomGetPositionX#(ode\geom),dGeomGetPositionY#(ode\geom),dGeomGetPositionZ#(ode\geom) Next End Function ; ################################################################################################### Look for 'OffsetPivot' to view the new code. You can adjust the camera height by changing the y-axis value (currently 5) here... PositionEntity OffsetPivot,0,5,0 You can adjust the camera angle by changing the y-axis value in the UpdateCam() function... PositionEntity CameraPivot,0,-2,-12

Al Meyer (Posted 2008) [#7]

Amazing! Many thanks. I studying all the codes deeply. :) All the best

Al Meyer (Posted 2008) [#8]

Hi Jim, I´m getting lots of progress with JV-ODE (excellent) and Blitz3D. I have stuck with one question, if you can help me: how can avoid camera penetrations in trimeshes? I put a mesh (a room) and made it a trimesh, but camera penetrates it sometimes. How can I avoid it?

VIP3R (Posted 2008) [#9]

Parent the camera to a small Blitz sphere and use Blitz collision checking against the visible room mesh entity (not the TriMesh). When the sphere comes into contact with the room mesh, both it and the camera will not be able to penetrate it. You will probably find much more info about this in the Blitz3D programming forums, as it applies whether physics are used or not.

Al Meyer (Posted 2008) [#10]

Thanks for the guide.

Al Meyer (Posted 2008) [#11]

"Parent the camera to a small Blitz sphere and use Blitz collision checking against the visible room mesh entity (not the TriMesh). When the sphere comes into contact with the room mesh, both it and the camera will not be able to penetrate it." I lost my entire day in this subject. No success :((( Thanks for the help

VIP3R (Posted 2008) [#12]

You need to look into 3rd person cameras, a quick search reveals these threads... http://www.blitzmax.com/Community/posts.php?topic=52890 http://www.blitzmax.com/Community/posts.php?topic=68571 If you still need help with it, post the question in the programming forums, you won't get much help on 3rd person cameras in the userlibs forum. Don't get too disheartened, some of this stuff is really hard for a beginner.