Incorrect lookat matrix - c++

Question

I've started working on shadow maps for directional lights and for that I need a lookAt matrix, but when I tried constructing from example of an online tutorial it looked something like this:
It currently looks like this:
https://media.giphy.com/media/QrMnqBBJZuATu/giphy.gif
I've tried multiple ways of constructing it but with no success, I checked if the normalization, cross and translation functions weren't correct but that wasn't the case. I've also tried changing from column-major matrices to row-major matrices but with no luck. Would someone be able to point out what I did wrong?
Lookat matrix constructing:
Center vector = (0, 0, 0),
Up vector = (0, 1, 0)
Matrix4f Matrix4f::lookAt(const Vector3f& position, const Vector3f& center, const Vector3f& up) {
Matrix4f out(1.0f);
Vector3f z = position.substract(center).normalize();
Vector3f y = up;
Vector3f x = y.cross(z).normalize();
y = z.cross(x);
out.mElements[0 * 4 + 0] = x.x;
out.mElements[0 * 4 + 1] = x.y;
out.mElements[0 * 4 + 2] = x.z;
out.mElements[1 * 4 + 0] = y.x;
out.mElements[1 * 4 + 1] = y.y;
out.mElements[1 * 4 + 2] = y.z;
out.mElements[2 * 4 + 0] = z.x;
out.mElements[2 * 4 + 1] = z.y;
out.mElements[2 * 4 + 2] = z.z;
return (out * Matrix4f::translation(Vector3f(-position.x, -position.y, -position.z)));
}
}
Credit for code: https://stackoverflow.com/users/5577765/rabbid76
This is how I pass a matrix to the shader:
void Shader::setMat4(const char* name, const math::Matrix4f& matrix){
glUniformMatrix4fv(getUniformLocation(name), 1, GL_TRUE, matrix.mElements);
}
After I've calculated the lookAt matrix I directly pass it to the vertex shader to the uniform: view and calculate a point like this:
gl_Position = projection * view * model * vec4(vertexPosition, 1.0);
And this is how my matrix multiplication works:
Matrix4f Matrix4f::multiply(const Matrix4f& other) const {
Matrix4f out;
for (int y = 0; y < 4; y++) {
for (int x = 0; x < 4; x++) {
fl32 o = 0;
for (int c = 0; c < 4; c++) {
o += this->mElements[c + y * 4] * other.mElements[x + c * 4]; }
out.mElements[x + y * 4] = o;
}
}
return out;
}
Edit: updated picture
Edit: Added a more detailed description

Answer 1

You need to normalize s before u is calculated. I'm not sure if it is the only problem

Answer 2

If your positions (position, center) and the up vector are in viewport space, then the Z-Axis of the view matrix is the inverse line of sight and the Y-Axis is the up vector. See the following code:
Matrix4f Matrix4f::lookAt(const Vector3f& position, const Vector3f& center, const Vector3f& up)
{
Matrix4f out(1.0f); // I suppose this initilizes a 4*4 identity matrix
// Z-Axis is the line of sight
Vector3f z = position.substract(center).normalize(); // inverse line of sight
// Y-Axis is the up vector
Vector3f y = up;
// X-Axis is the cross product of Y-Axis and Z-Axis
Vector3f x = y.cross(z).normalize();
// orthonormalize the Y-Axis
y = z.cross( x );
out.mElements[0*4 + 0] = x.x;
out.mElements[0*4 + 1] = x.y;
out.mElements[0*4 + 2] = x.z;
out.mElements[1*4 + 0] = y.x;
out.mElements[1*4 + 1] = y.y;
out.mElements[1*4 + 2] = y.z;
out.mElements[2*4 + 0] = z.x;
out.mElements[2*4 + 1] = z.y;
out.mElements[2*4 + 2] = z.z;
return (out * Matrix4f::translation(Vector3f(-position.x, -position.y, -position.z)));
}

Answer 3

After hours of trying to make the lookat matrix working I had given up on way of constructing the lookat matrix, instead I constructed a lookat matrix based on the position of the camera and position the camera should look at, using trigonometry functions I was able to create the result which I was seeking.
My current way of constructing a lookat matrix:
Matrix4f Matrix4f::lookAt(const Vector3f& position, const Vector3f& center) {
Vector3f deltaVector = (position - center).normalize();
fl32 yaw = (fl32)radToDeg(atan(deltaVector.x / deltaVector.z));
fl32 pitch = (fl32)radToDeg(acos(Vector2f(deltaVector.x, deltaVector.z).magnitude()));
if (deltaVector.z > 0)
yaw = yaw - 180.0f;
Matrix4f yRotation = Matrix4f::rotation(Vector3f(0.0f, 1.0f, 0.0f), -yaw);
Matrix4f xRotation = Matrix4f::rotation(Vector3f(1.0f, 0.0f, 0.0f), pitch);
Matrix4f translation = Matrix4f::translation(position);
return (translation * (yRotation * xRotation));
}