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Height field terrain shape fixes from tomva1@yahoo.com

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This commit is contained in:
john.mccutchan
2009-02-09 16:28:44 +00:00
parent 0a94209df1
commit cd126aae8f
2 changed files with 23 additions and 10 deletions
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20
src/BulletCollision/CollisionShapes/btHeightfieldTerrainShape.cpp
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@@ -144,7 +144,12 @@ void btHeightfieldTerrainShape::getAabb(const btTransform& t,btVector3& aabbMin,
aabbMax = center + extent; aabbMax = center + extent;
} }
btScalar btHeightfieldTerrainShape::getHeightFieldValue(int x,int y) const
/// This returns the "raw" (user's initial) height, not the actual height.
/// The actual height needs to be adjusted to be relative to the center
/// of the heightfield's AABB.
btScalar
btHeightfieldTerrainShape::getRawHeightFieldValue(int x,int y) const
{ {
btScalar val = 0.f; btScalar val = 0.f;
switch (m_heightDataType) switch (m_heightDataType)
@@ -181,24 +186,22 @@ btScalar btHeightfieldTerrainShape::getHeightFieldValue(int x,int y) const
/// this returns the vertex in bullet-local coordinates
void btHeightfieldTerrainShape::getVertex(int x,int y,btVector3& vertex) const void btHeightfieldTerrainShape::getVertex(int x,int y,btVector3& vertex) const
{ {
btAssert(x>=0); btAssert(x>=0);
btAssert(y>=0); btAssert(y>=0);
btAssert(x<m_heightStickWidth); btAssert(x<m_heightStickWidth);
btAssert(y<m_heightStickLength); btAssert(y<m_heightStickLength);
btScalar height = getRawHeightFieldValue(x,y);
btScalar height = getHeightFieldValue(x,y);
switch (m_upAxis) switch (m_upAxis)
{ {
case 0: case 0:
{ {
vertex.setValue( vertex.setValue(
height, height - m_localOrigin.getX(),
(-m_width/btScalar(2.0)) + x, (-m_width/btScalar(2.0)) + x,
(-m_length/btScalar(2.0) ) + y (-m_length/btScalar(2.0) ) + y
); );
@@ -208,7 +211,7 @@ void btHeightfieldTerrainShape::getVertex(int x,int y,btVector3& vertex) const
{ {
vertex.setValue( vertex.setValue(
(-m_width/btScalar(2.0)) + x, (-m_width/btScalar(2.0)) + x,
height, height - m_localOrigin.getY(),
(-m_length/btScalar(2.0)) + y (-m_length/btScalar(2.0)) + y
); );
break; break;
@@ -218,7 +221,7 @@ void btHeightfieldTerrainShape::getVertex(int x,int y,btVector3& vertex) const
vertex.setValue( vertex.setValue(
(-m_width/btScalar(2.0)) + x, (-m_width/btScalar(2.0)) + x,
(-m_length/btScalar(2.0)) + y, (-m_length/btScalar(2.0)) + y,
height height - m_localOrigin.getZ()
); );
break; break;
} }
@@ -230,7 +233,6 @@ void btHeightfieldTerrainShape::getVertex(int x,int y,btVector3& vertex) const
} }
vertex*=m_localScaling; vertex*=m_localScaling;
} }

13
src/BulletCollision/CollisionShapes/btHeightfieldTerrainShape.h
View File

@@ -30,6 +30,17 @@ subject to the following restrictions:
center (as determined by width and length and height, with each center (as determined by width and length and height, with each
axis multiplied by the localScaling). axis multiplied by the localScaling).
\b NOTE: be careful with coordinates. If you have a heightfield with a local
min height of -100m, and a max height of +500m, you may be tempted to place it
at the origin (0,0) and expect the heights in world coordinates to be
-100 to +500 meters.
Actually, the heights will be -300 to +300m, because bullet will re-center
the heightfield based on its AABB (which is determined by the min/max
heights). So keep in mind that once you create a btHeightfieldTerrainShape
object, the heights will be adjusted relative to the center of the AABB. This
is different to the behavior of many rendering engines, but is useful for
physics engines.
Most (but not all) rendering and heightfield libraries assume upAxis = 1 Most (but not all) rendering and heightfield libraries assume upAxis = 1
(that is, the y-axis is "up"). This class allows any of the 3 coordinates (that is, the y-axis is "up"). This class allows any of the 3 coordinates
to be "up". Make sure your choice of axis is consistent with your rendering to be "up". Make sure your choice of axis is consistent with your rendering
@@ -88,7 +99,7 @@ protected:
btVector3 m_localScaling; btVector3 m_localScaling;
virtual btScalar getHeightFieldValue(int x,int y) const; virtual btScalar getRawHeightFieldValue(int x,int y) const;
void quantizeWithClamp(int* out, const btVector3& point,int isMax) const; void quantizeWithClamp(int* out, const btVector3& point,int isMax) const;
void getVertex(int x,int y,btVector3& vertex) const; void getVertex(int x,int y,btVector3& vertex) const;