Tire brakes trace on road
Blitz3D Forums/Blitz3D Programming/Tire brakes trace on road
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| ..hi guys...could some give me some hints or maybe some piece of code, how to achieve tire marks on road during intense use of breaks or sliding/drifting?? I really dont have clue where to start, so i would appreciate explanation and maybe some piece of code if anyone willing to share...thank you.. |
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| I used a system where I had 2 pivots attached to each rear wheel (but you could use a local t-formed coord system here to remove the need for pivot entities) I place one pivot at the point where the inside wheel edge contacts the floor, the other at the point where the outside edge contacts the floor. Done for both rear wheels this gives you 4 pivots. I then created an empty mesh with a single surface with an appropriate material on it, such as a 50% black blend or something, as I wasn't going to texture map the skids, although that's fairly easy to do. When a skidmark is triggered I added 4 new vertices to the surface at the position of the 4 pivots (call these L1 and L2 for the left wheel, and R1 and R2 for the right wheel) then setup a counter that decreases. Once the counter reaches zero (ie. allowing the car to skid certain distance) I add 4 more verts (L3 and L4, and R3 and R4) and create a quad polygon using L1,L2,L3 and L4, and another polygon using R1,R2,R3 and R4. I then repeat this process for as long as the skid continues, creating 2 curved polygon skidmarks that roughly follow the path of the 2 wheels. Varying the counter adjusts the blockiness of the skidmarks - a lower counter adds vertices more often, creating a smoother look but using more verts and polys over a certain distance - balance it to get the right look depending upon how long your skids are and how often they occur, and how close the camera is. The only tricky bit is telling when a skid starts and ends and therefore creating a new set of start verts for each seperate skid to ensure you don't get big stretched polys across the world. You also need to keep an eye on the number of verts in the new mesh to ensure it doesn't get too high, perhaps removing the verts in order of oldest first or culling them after a certain time. |
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| I sometimes use particles aligned to the floor and with a short lifetime, enough to drive on and spin a little, before they disappear. OR As Vordeman suggests use something like the trails code (possibly in the archive) as superbly used in RocketBoards. I can probably dig out the code if you should need it. IPete2. |
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| hi Ipete, I would apprechiate that function-code if you dont mind...is it possible to texture generated trails you talking about Ipete2?? |
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| hi, there is a sample, in blitz samples, in Mark directory -> Tron... this is part of the code, creating a mesh with vertexs... If add_flag AddVertex trail_surf,EntityX(bike),2,EntityZ(bike),0,0 AddVertex trail_surf,EntityX(bike),0,EntityZ(bike),0,1 AddTriangle trail_surf,trail_vert,trail_vert+2,trail_vert+3 AddTriangle trail_surf,trail_vert,trail_vert+3,trail_vert+1 AddTriangle trail_surf,trail_vert,trail_vert+3,trail_vert+2 AddTriangle trail_surf,trail_vert,trail_vert+1,trail_vert+3 trail_vert=trail_vert+2 Else VertexCoords trail_surf,trail_vert,EntityX(car),EntityY(car),EntityZ(car) VertexCoords trail_surf,trail_vert+1,EntityX(car),EntityY(car),EntityZ(car) EndIf |
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| Hiya Naughty, I used particles to create a tyre texture in snow - see here:  This was generated by particle candy. But the trails ones were using this code and no textures were employed: THIS CODE IS FROM ROCKET BOARDERS a brilliant little game but I forgot who developed it sorry - but they should have credit for developing the functions, I just used them. :) [edit thanks to Gabriel for this info: Rocket Boards was developed by Ben Gillbanks ] To begin in your set up you need this: ; TRAILS ********************** Const trail_update=1 ; trail update frequency (lower number updates more often) Const maxVerts=200 ; maximum number of verts per trail object (polygons * 2) Global Trailson= False Type trail Field id Field tdx#[maxVerts], tdy#[maxVerts], tdz#[maxVerts] Field update Field surface Field point1, point2 Field Trailson End Type ; TRAILS ********************** Then call the CREATE function and pass parameteres to it to start trails. Every update call the UPDATE TRAILS function, and should you wish to stop the trails call the free trails function. i.e. if your car leaps a cravass or flies off a ramp etc. The update takes care of keeping a lid on the max number of polys used (200 in my game). ;----------------- ;update all trails ;----------------- Function UpdateTrails() Local x#,y#,z# ;loop through all trails For t.trail = Each trail If Trailson = True Then ; Move the trail pieces along. t\update=t\update+1 : If t\update=trail_update Then t\update=0 ;update If t\update=0 For i=2 To CountVertices(t\surface)-1 t\tdx[i] = (VertexX(t\surface,i-2) - VertexX(t\surface,i))/trail_update t\tdy[i] = (VertexY(t\surface,i-2) - VertexY(t\surface,i))/trail_update t\tdz[i] = (VertexZ(t\surface,i-2) - VertexZ(t\surface,i))/trail_update Next End If For i=2 To CountVertices(t\surface)-1 VertexCoords(t\surface,i,VertexX(t\surface,i)+t\tdx[i],VertexY(t\surface,i)+t\tdy[i],VertexZ(t\surface,i)+t\tdz[i]) Next EntityAlpha t\id,Abs(movespeed)/50 ;position the first two verts at the back of yourCharacter VertexCoords(t\surface,0,EntityX(t\point1,1),EntityY(t\point1,1),EntityZ(t\point1,1)) VertexCoords(t\surface,1,EntityX(t\point2,1),EntityY(t\point2,1),EntityZ(t\point2,1)) End If Next End Function ;--------------------- ;create a trail object ;--------------------- Function CreateTrail(point1,point2,polys=100,alpha#=1) Local x#,y#,z# Trailson = True ; ensure TRAILS are turned on t.trail=New trail ;create mesh and set properties mesh = CreateMesh() t\surface = CreateSurface(mesh) t\id = mesh ;check there are two trail strat points If point1=False Then RuntimeError "You must specify 'point1' for one side of the trail" Else t\point1=point1 If point2=False Then RuntimeError "You must specify 'point2' for one side of the trail" Else t\point2=point2 ;mid pount between two trial objects x=(EntityX(t\point1,1)+EntityX(t\point2,1))/2 y=(EntityY(t\point1,1)+EntityY(t\point2,1))/2 z=(EntityZ(t\point1,1)+EntityZ(t\point2,1))/2 ;create polygons For i=0 To polys AddVertex t\surface,x,y,z,Float(i)/Float(polys),1,0 AddVertex t\surface,x,y,z,Float(i)/Float(polys),0,0 If i>0 AddTriangle t\surface,i*2,i*2-1,i*2-2 AddTriangle t\surface,i*2,i*2+1,i*2-1 End If Next ;set trail properties EntityFX mesh,17 EntityAlpha mesh,alpha Return mesh End Function ;-------------------------------- ;free trail and delete trail type ;-------------------------------- Function free_trail(id) For t.trail=Each trail If t\id=id t\Trailson = False ; turn trails off PMC FreeEntity t\id Delete t EndIf Next Return True End Function |
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| thank you a lot Ipete2... cheers man ;) |
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| my pleasure Naughty! I have to say that I used this code to great extent to produce some wonderful snow and ice trails in a 'little' game I did last year, there was a level based in the winter, and this code really added to the feel of speed and snow/ice. I am not allowed to post images of that particular project here, but I may put some on my website for you guys to oggle at. IPete2. |
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| Rocket Boards was developed by Ben Gillbanks. Still one of my favourite Blitz games of all time. |
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| Thanks Gabriel, I have edited the above post to give proper credit as it should be. IPete2. |
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