I am using GLM to do some stuff and a function I wrote doesn't have the effect I intended, so I looked at a matrix while debugging to see what values it had in it. Surprisingly, it contains 4 arrays (vec4's?) of 12 values each! In each array, the values repeat. I am guessing that I should take the first 4 values of each array to be the actual values in the matrix. Do these become the rows? Or the columns? Do I not take the first 4 values?
Thanks!
Edit: While I do want to know the answer to the above I tried a different tack on debugging and I have a new question about the same problem that prompted the above question. Rather than make a new post I will add the question here.
I have objects I wish to calculate the centres of. Because of the way they were written in the Collada file, I need to rotate them -90 degrees on the X axis to make them sit on the ground. I had success by swapping the Y and Z axes, then multiplying the new Z axis by -1, while calculating their centres.
Then I found out about GLM and wrote a function to rotate a vector to replace the bulky code. It did not work. After looking at the points that came out on each way, realised that my old way had been rotating it +90 instead of -90, so tried sending -1* the angle into my function instead. Looked at the points and it gets the same values (approximately --- one value is 0.00097.. instead of 0.0012..) as the old way, except the world is wrong. A little less wrong than before (the floor is only five or so units off in the y and z directions instead of a thin line in the distance) but still wrong.
I just cannot figure out what might be going wrong. Can anyone shed some light on this?
Here is the function that rotates a vector in case it's wrong (I don't think it is). The find centre function is below it, it seems if I post 2 things with code tags, one of them disappears. The "working" and "try sections are the old way/new way respectively. m_Rot.x is always -90 and y and x 0.
vec4 RotateVec (float XAngle, float YAngle, float ZAngle, vec4 Pivot, vec4 P)
{
//TEST
mat4 test = mat4(1.0f);
//..Translate to origin
mat4 RotationMatrix = translate(test, vec3(-Pivot.x, 0.0f, 0.0f));
RotationMatrix = translate(RotationMatrix, vec3(0.0f, -Pivot.y, 0.0f));
RotationMatrix = translate(RotationMatrix, vec3(0.0f, 0.0f, -Pivot.z));
//..Do rotations
RotationMatrix = rotate(RotationMatrix, XAngle, vec3(1,0,0));
RotationMatrix = rotate(RotationMatrix, YAngle, vec3(0,1,0));
RotationMatrix = rotate(RotationMatrix, ZAngle, vec3(0,0,1));
//..Put back
RotationMatrix = translate(RotationMatrix, vec3(Pivot.x, 0.0f, 0.0f));
RotationMatrix = translate(RotationMatrix, vec3(0.0f, Pivot.y, 0.0f));
RotationMatrix = translate(RotationMatrix, vec3(0.0f, 0.0f, Pivot.z));
vec4 ResultVec = P * RotationMatrix;
return ResultVec;
}
void ColladaObject::FindRotCentre (vec4 Pivot, float XAngle, float YAngle, float ZAngle, Pos& Max, Pos& Min)
{
m_pCollada->m_MaterialMap.StartIterator ();
while(m_pCollada->m_MaterialMap.Get()->m_Mesh.size () == 0)
{
m_pCollada->m_MaterialMap.MoveNext ();
}
//***working? with no random angles
/*TPos<int> Axes (X_AXIS, Y_AXIS, Z_AXIS);
TPos<float> Angles (XAngle, YAngle, ZAngle);
int mult = 1;
if(m_Rot.x == 90 || m_Rot.x == -90) //this section may need tweaking if things end up facing backward or upside down or anything
{
Axes.y = Z_AXIS;
Angles.y = ZAngle;
Axes.z = Y_AXIS;
Angles.z = YAngle;
if(m_Rot.x == -90)
{
mult = -1;
}
}
if(m_Rot.y == 90 || m_Rot.y == -90)
{
Axes.x = Z_AXIS;
Angles.x = ZAngle;
Axes.z = X_AXIS;
Angles.z = XAngle;
}
if(m_Rot.z == 90 || m_Rot.z == -90)
{
Axes.y = X_AXIS;
Angles.y = XAngle;
Axes.x = Y_AXIS;
Angles.x = YAngle;
}*/
vec4 P; //dont comment out this line
/*P.x = m_pCollada->m_MaterialMap.Get()->m_Mesh.at(0).m_Positions[Axes.x];
P.y = m_pCollada->m_MaterialMap.Get()->m_Mesh.at(0).m_Positions[Axes.y];
P.z = mult*m_pCollada->m_MaterialMap.Get()->m_Mesh.at(0).m_Positions[Axes.z];
P.w = 1;
//P = RotateVec (Angles.x, Angles.y, Angles.z, Pivot, P);*/
//***end working?
//***try
P.x = m_pCollada->m_MaterialMap.Get()->m_Mesh.at(0).m_Positions[0];
P.y = m_pCollada->m_MaterialMap.Get()->m_Mesh.at(0).m_Positions[1];
P.z = m_pCollada->m_MaterialMap.Get()->m_Mesh.at(0).m_Positions[2];
P.w = 1;
P = RotateVec (-1*m_Rot.x, -1*m_Rot.y, -1*m_Rot.z, Pivot, P);
//P = RotateVec (XAngle, YAngle, ZAngle, Pivot, P);
//***end try
float MaxX = P.x;
float MinX = P.x;
float MaxY = P.y;
float MinY = P.y;
float MaxZ = P.z;
float MinZ = P.z;
while(!m_pCollada->m_MaterialMap.IsEOM ())
{
shared_ptr<Material> pMaterial = m_pCollada->m_MaterialMap.Get();
for (int i = 0; i < pMaterial->m_Mesh.size (); i ++)
{
//***working?
/*P.x = m_pCollada->m_MaterialMap.Get()->m_Mesh.at(0).m_Positions[Axes.x];
P.y = m_pCollada->m_MaterialMap.Get()->m_Mesh.at(0).m_Positions[Axes.y];
P.z = mult*m_pCollada->m_MaterialMap.Get()->m_Mesh.at(0).m_Positions[Axes.z];
P.w = 1;
//P = RotateVec (Angles.x, Angles.y, Angles.z, Pivot, P);*/
//***end working?
//***try
P.x = m_pCollada->m_MaterialMap.Get()->m_Mesh.at(0).m_Positions[0];
P.y = m_pCollada->m_MaterialMap.Get()->m_Mesh.at(0).m_Positions[1];
P.z = m_pCollada->m_MaterialMap.Get()->m_Mesh.at(0).m_Positions[2];
P = RotateVec (-1*m_Rot.x, -1*m_Rot.y, -1*m_Rot.z, Pivot, P);
//P = RotateVec (XAngle, YAngle, ZAngle, Pivot, P);
//***end try
if(MaxX < P.x)
{
MaxX = P.x;
}
else if(MinX > P.x)
{
MinX = P.x;
}
if(MaxY < P.y)
{
MaxY = P.y;
}
else if(MinY > P.y)
{
MinY = P.y;
}
if(MaxZ < P.z)
{
MaxZ = P.z;
}
else if(MinZ > P.z)
{
MinZ = P.z;
}
}
m_pCollada->m_MaterialMap.MoveNext ();
}
m_Centre.x = MinX + (MaxX - MinX)/2;
m_Centre.y = MinY + (MaxY - MinY)/2;
m_Centre.z = MinZ + (MaxZ - MinZ)/2;
Min.x = MinX - m_Centre.x;
Max.x = MaxX - m_Centre.x;
Min.y = MinY - m_Centre.y;
Max.y = MaxY - m_Centre.y;
Min.z = MinZ - m_Centre.z;
Max.z = MaxZ - m_Centre.z;
}
