Accurate Collision Detection with Terrains

[DarkWhoppy]

Is there a way to get more accurate collision detection when using a terrain (model) or heightmap file? I've been trying... but when I use a heightmap file I can't actually get ahold of the mesh for the triangle selector so that doesn't work.

When using a terrain generated with MilkShape the model I use for testing 'floats' over the terrain making the shadow appear afew 100 units to the left/right (depending on what position I move to) of the model.
ScreenShot: www.phyer.net/whoppyarts/temp/shadow_funny.JPG

Yes, I tried decreasing the radius of the ellipsoid, that didn't work. But, the model does move "up and down" along with the hills of the terrain.

If anyone has a solution to this please let me know.

[Peter Müller]

I take an ITriangleSelector to get the current hight of the terrain for characters and for jeeps for something you should use an physik engine

[DarkWhoppy]

Jeeps? I didn't mention anything about a vehicle...

[Peter Müller]

This was only an example

Edit:
My models stand on the floor, using the method, I explained:
http://raf.games-forge.de/v07/source/pr ... 20aussieht.

[DarkWhoppy]

I take an ITriangleSelector to get the current hight of the terrain for characters

I don't understand what you're doing there, could you explain further?

[thesmileman]

DarkWhoopy, if you are using a TerrainSceneNode you can just modify the models Z cordinates and set it equal to the height of the terrain at that point

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//Move node in the direction you want then:

vector3df pos3d = fairyNode->getPosition();
pos3d.z = terNode->getHeight(vector2d(pos3d.X,pos3d.Y))  //modify height to match terrain height
fairyNode->setPosition(pos3d);

Oh and don't trust my sintax.

[DarkWhoppy]

Ah dammit, didn't check the API for a getHeight function

Thanks

[DarkWhoppy]

Now she falls right through the terrain but stops at the bottom of its bounding box...

Code: Select all

mTerrain = mhandle->getSmgr()->addTerrainSceneNode(0,1,
                    mhandle->driver->createImageFromFile("Data/maps/grassplain_sk.bmp"),
                    mhandle->driver->createImageFromFile("Data/maps/terrian1.bmp"),0,
                    core::dimension2d< f32 >(10.0f, 10.0f), 150.0f, core::dimension2d< s32 >(64, 64));
mTerrain->setMaterialFlag(EMF_LIGHTING, false);

//Inside update function

vector3df pos3d = vector3df(mPlayerNode->getPosition()); 
    mTerrain->getHeight(core::vector2d<f32>(pos3d.X,pos3d.Z),pos3d.Y);  
    mPlayerNode->setPosition(pos3d); 

I can't get the mesh for the triangle selector
Someone have a terrian/collision example?

[thesmileman]

I wouldn't think bounding box collision would work very well with terrains onless they are flat have you tried the other types of collision detection?

[DarkWhoppy]

The engine has other types besides BoundingBox collision?

(been a while since I last used Irrlicht)

[Peter Müller]

Get the hight of the terrain at an position (x/z) using the ITriangleSelector an any other getHeight method.
Then get the relative vector form the cradle (origin) of your model to the position, where the model should stand on the floor.

Then
amsnModel->setPosition(vector3df(x + vRelVector.X, fTerrainHeight + vRelVector.Y, z + vRelVector.Z));

[thesmileman]

The engine has other types besides BoundingBox collision?

(been a while since I last used Irrlicht)

Yea check out the tutorials on colission detection all three types are shown I think.

[Peter Müller]

Three? I thougt, two, BoundingBox and TriangleSelection

[thesmileman]

Plus "manual scene node picking"

[DarkWhoppy]

No wonder! I checked the source files and.... I guess i'll have to find another solution for now

Code: Select all

//! Calculates height of a point in the terrain
bool CTerrainSceneNode::getHeight(core::vector2d<f32> pos, f32& outHeight)
{
	return false;
}