Hmm okay, thx, it's getting a bit more clear now :) Just that I am using OpenGL so no d3dx for me ;) Still though, I was planning to calculate the height and wether it should be blocked by checking the tiles around it. So I have no idea how to go about doing that now.
[Edited by - PinguinDude on June 11, 2007 12:03:14 AM]
Heightmap + Collision detection.
just replace the d3dx calls with your own planeEquation functions. google for planeEquation.
here:
here:
vec3 AB = p1-3p0;vec AC = p2-p0; planeEquation.Pn = AB.crossProduct(AC);planeEquation.Pn.normalize(); planeEquation.D = -planeEquation.Pn.dot(p0);
Author
Yes, but I still didn't quite understand what to do after I did calculate the plane heights... :\ I'm sorry but this is all very new to me.
First, two things that are going to help you:
#1. You need a function that takes the X and Z coordinates of your heightmap as integers and returns a Y value as a float.
#2. You need a second function that takes floats and takes X,Z, and scaling information and returns your Y. It should lerp to get the proper height, eg:
Ok, now you have some options. I think the easiest one would be something like this:
#1. You need a function that takes the X and Z coordinates of your heightmap as integers and returns a Y value as a float.
#2. You need a second function that takes floats and takes X,Z, and scaling information and returns your Y. It should lerp to get the proper height, eg:
// a < b, 0 < x < 1float lerp(float a, float b, float x) { return (b-a)*x+a;}float getHeighti(int x, int z) { return something;}float getHeightf(float x, float z, float scaleXZ, float scaleY) { x /= scaleXZ; z /= scaleXZ; int Xa = (int)floor(x); // x on one side int Xb = (int)floor(x+1.0f); // x on the other side int Za = (int)floor(z); // z on one side int Zb = (int)floor(z+1.0f); // z on the other side float Xd = x-floor(x); if (Xd < 0.0f) Xd *= -1.0f; float Zd = z-floor(z); if (Zd < 0.0f) Zd *= -1.0f; float b = lerp(getHeighti(Xa,Zb),getHeighti(Xb,Zb),Xd); float a = lerp(getHeighti(Xa,Za),getHeighti(Xb,Za),Xd); return scaleY*lerp(a,b,Zd);}Ok, now you have some options. I think the easiest one would be something like this:
float x,z; // Coordinates now float x1,z1; // Where they want to go float rise = getHeightf(x1,z1)-getHeightf(x,z); float run; // How far one step is if (rise/run < some_threshold) move_player_to(x1,z1); else twist_ankle();
Author
Ok, currently I got this code which somewhat works... but it really depends on hte values of the map.. it is far from what I want :( I'm getting really confused and tired of this.
/// MoveEntity. Moves an entity from it's current position to an other position.int EntityManager::MoveEntity(BaseEntity *entity, float speed){ Vector cp, cr, tp, np, op, ha, hb, hc, hd, he, hf, hg, hh, deg; HeightObject *object = NULL; frametime_t *timer = engine->GetTimer(); curframe = timer->curtime * 0.001f; lastframe = timer->lasttime * 0.001f; if (!entity) return 1; // Retrieve entities current position and rotation. cp = entity->GetPosition(); cr = entity->GetRotation(); // Negative speed or positive speed. if ((cr.GetZ() > 90) && (cr.GetZ() < 270)) speed = -speed; // Retrieve vertice position in the map. if (entities.at(0) != NULL) object = ((HeightObject*)(entities[0]->GetModel())); // Calculate new position, check if a hill is steeper than 65 degrees. tp.SetX( tp.GetX() + ( (sin(cr.GetZ() * ANG2RAD) * RAD2ANG) * (speed * (curframe - lastframe)))); tp.SetZ( tp.GetZ() + ( (cos(cr.GetZ() * ANG2RAD) * RAD2ANG) * (speed * (curframe - lastframe)))); // Get the object's current plane position. ha = object->GetVertice(Vector(fabs(cp.GetZ() / 20.0f), fabs(cp.GetX() / 20.0f), 0, 0)); hb = object->GetVertice(Vector(fabs(cp.GetZ() / 20.0f) + 1, fabs(cp.GetX() / 20.0f), 0, 0)); hc = object->GetVertice(Vector(fabs(cp.GetZ() / 20.0f) + 1, fabs(cp.GetX() / 20.0f) + 1, 0, 0)); hd = object->GetVertice(Vector(fabs(cp.GetZ() / 20.0f), fabs(cp.GetX() / 20.0f) + 1, 0, 0)); // Get the object's new plane position. he = object->GetVertice(Vector(fabs(tp.GetZ() / 20.0f), fabs(tp.GetX() / 20.0f), 0, 0)); hf = object->GetVertice(Vector(fabs(tp.GetZ() / 20.0f) + 1, fabs(tp.GetX() / 20.0f), 0, 0)); hg = object->GetVertice(Vector(fabs(tp.GetZ() / 20.0f) + 1, fabs(tp.GetX() / 20.0f) + 1, 0, 0)); hh = object->GetVertice(Vector(fabs(tp.GetZ() / 20.0f), fabs(tp.GetX() / 20.0f) + 1, 0, 0)); // Perform a bilinear interpolation. float tx = cp.GetX() / 20.0f - float(cp.GetX() / 20.0f); float ty = cp.GetZ() / 20.0f - float(cp.GetZ() / 20.0f); float xy = tx * ty; float h = ha.GetY() * (1.0f - ty - tx + xy) + hb.GetY() * (tx - xy) + hc.GetY() * xy + hd.GetY() * (ty - xy); np.SetY(h); // Adjust the Y value so the object is always on top of the terrain. cp.SetY(np.GetY() + entity->GetModel()->GetBoundingBox().GetMax().GetY()); float txa = tp.GetX() / 20.0f - float(tp.GetX() / 20.0f); float tya = tp.GetZ() / 20.0f - float(tp.GetZ() / 20.0f); float xya = txa * tya; float haa = he.GetY() * (1.0f - tya - txa + xya) + hf.GetY() * (txa - xya) + hg.GetY() * xya + hh.GetY() * (tya - xya); std::cout << haa << " " << h << " " << h / haa << std::endl; if (h / haa <= 0.7) { // Update our current position. cp.SetX( cp.GetX() + ( (sin(cr.GetZ() * ANG2RAD) * RAD2ANG) * (speed * (curframe - lastframe)))); cp.SetZ( cp.GetZ() + ( (cos(cr.GetZ() * ANG2RAD) * RAD2ANG) * (speed * (curframe - lastframe)))); } // Set the new position. entity->SetPosition(cp); return 0;}
I've been trying to find a way to allow me to move many units over a height map, but ray tracing the mesh became way to expensive with as many units as I have, and someone thankfully directed me to this thread.
There were a few different ways I saw people doing the math on this, but I decided to go with Bluechip's plane approach. Everything works out great except the values are somehow, just slightly off near the origin, but as I get further away it becomes more apparent.
This is what I'm trying to use now:
//tempPtr is a pointer to a single unit that I am working with at the moment.
I've gone through over and over and checked all of the code(all the math adds up) and I understand and know its all correct up to the point involving the final formula for obtaining the height position. Is it just that this formula isn't correct?
Thanks for any help anyone can give me, I've spent most of the day playing with it. ><
[Edited by - WarisSweet on June 21, 2007 10:00:19 AM]
There were a few different ways I saw people doing the math on this, but I decided to go with Bluechip's plane approach. Everything works out great except the values are somehow, just slightly off near the origin, but as I get further away it becomes more apparent.
This is what I'm trying to use now:
//tempPtr is a pointer to a single unit that I am working with at the moment.
D3DXVECTOR3 A, B, C, D;A = B = C = D = D3DXVECTOR3(0.0f, 0.0f, 0.0f);A.x = ((int)(tempPtr->m_position.x / 10)) * 10;A.y = this->m_objectManager.m_map.m_heightMap[(int)(tempPtr->m_position.x/10)][(int)(tempPtr->m_position.z/10) + 1];A.z = ((int)(tempPtr->m_position.z / 10)) * 10 + 10;B.x = ((int)(tempPtr->m_position.x / 10)) * 10 + 10;B.y = this->m_objectManager.m_map.m_heightMap[(int)(tempPtr->m_position.x/10) + 1][(int)(tempPtr->m_position.z/10) + 1];B.z = ((int)(tempPtr->m_position.z / 10)) * 10 + 10;C.x = ((int)(tempPtr->m_position.x / 10)) * 10;C.y = this->m_objectManager.m_map.m_heightMap[(int)(tempPtr->m_position.x/10)][(int)(tempPtr->m_position.z/10)];C.z = ((int)(tempPtr->m_position.z / 10)) * 10;D.x = ((int)(tempPtr->m_position.x / 10)) * 10 + 10;D.y = this->m_objectManager.m_map.m_heightMap[(int)(tempPtr->m_position.x/10) + 1][(int)(tempPtr->m_position.z/10)];D.z = ((int)(tempPtr->m_position.z / 10)) * 10;float coefX = B.x - tempPtr->m_position.x;float coefZ = B.z - tempPtr->m_position.z;D3DXPLANE plane;if(coefX >= coefZ){ D3DXPlaneFromPoints(&plane, &A,&B,&D);}else{ D3DXPlaneFromPoints(&plane, &A,&D,&C);}tempPtr->m_targetPosition.y = (-tempPtr->m_position.x * plane.a - tempPtr->m_position.z * plane.c - plane.d) / plane.b;I've gone through over and over and checked all of the code(all the math adds up) and I understand and know its all correct up to the point involving the final formula for obtaining the height position. Is it just that this formula isn't correct?
Thanks for any help anyone can give me, I've spent most of the day playing with it. ><
[Edited by - WarisSweet on June 21, 2007 10:00:19 AM]
2PinguinDude
You build terrain as triangles based on hights. So, at any moment your model positioned on single triangle. Than you performe moving. Your moving is plane, as a fact. Let's examine Y as hight. So you move your point in ZX plane. Let's assume your speed in ZX constant (does not depend on plane angle). Then your move is
pos_new = pos_old + Vx*dt + Vy*dt. So you have fraction (pos_old, pos_new). Equation for this fraction is:
pos(t) = pos_old + t*(pos_new-pos_old); where t = {0,1};
After we found our fraction, we should find all triangles we intersect. Remember - intersection is flat! Result of intersection gives us list of such data structures:
struct sItersectionData{
double t; // time of intersection
sTringle triangle; // triangle we were intersected
};
Now we should sort this list by minimum t. That gives us information, what triangles we where intersect first. Let us point, that we have still one triangle, we are not intrested in - triangle we are on! We just drop it from list.
Let's itarate intersections list. Iteration element has triangle. We check that triangle to be too stepp. If it is not too steep - continue iteration. If it is steep enough, we found our stop point. It calcucates from pos(t). For reason to have no problems on the edge, lets assume that stop point is pos(t-delta).
Problem solved.
Here is algo. Now you have to implement intersection function and check function for triangle. Check function is quite easy, but you need some optimisation for interseption function for fast work.
Cheers.
You build terrain as triangles based on hights. So, at any moment your model positioned on single triangle. Than you performe moving. Your moving is plane, as a fact. Let's examine Y as hight. So you move your point in ZX plane. Let's assume your speed in ZX constant (does not depend on plane angle). Then your move is
pos_new = pos_old + Vx*dt + Vy*dt. So you have fraction (pos_old, pos_new). Equation for this fraction is:
pos(t) = pos_old + t*(pos_new-pos_old); where t = {0,1};
After we found our fraction, we should find all triangles we intersect. Remember - intersection is flat! Result of intersection gives us list of such data structures:
struct sItersectionData{
double t; // time of intersection
sTringle triangle; // triangle we were intersected
};
Now we should sort this list by minimum t. That gives us information, what triangles we where intersect first. Let us point, that we have still one triangle, we are not intrested in - triangle we are on! We just drop it from list.
Let's itarate intersections list. Iteration element has triangle. We check that triangle to be too stepp. If it is not too steep - continue iteration. If it is steep enough, we found our stop point. It calcucates from pos(t). For reason to have no problems on the edge, lets assume that stop point is pos(t-delta).
Problem solved.
Here is algo. Now you have to implement intersection function and check function for triangle. Check function is quite easy, but you need some optimisation for interseption function for fast work.
Cheers.
This topic is closed to new replies.
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