View matrix in opengl

Question

Sorry for my clumsy question. But I don't know where I am wrong at creating view matrix.

I have the following code:

 createMatrix(vec4f(xAxis.x, xAxis.y, xAxis.z, dot(xAxis,eye)), 
 vec4f(  yAxis.x_, yAxis.y_, yAxis.z_, dot(yAxis,eye)), 
 vec4f(-zAxis.x_, -zAxis.y_, -zAxis.z_, -dot(zAxis,eye)), 
 vec4f(0, 0, 0, 1)); //column1, column2,...

I have tried to transpose it, but with no success. I have also tried to use gluLookAt(...) with success. At the reference page, I watched the remarks about the to-be-created matrix, and it seems the same as mine. Where I am wrong?

Answer 1

In openGl matrices are transposed in memory. So transpose the matrix is OK. But your code doesn't look correct.

So you are in OpenGl. OpenGl uses right handed coordinate system. And for RH is lookat function defined like this:

zaxis = normal(cameraPosition - cameraTarget)
xaxis = normal(cross(cameraUpVector, zaxis))
yaxis = cross(zaxis, xaxis)

 xaxis.x           yaxis.x           zaxis.x          0
 xaxis.y           yaxis.y           zaxis.y          0
 xaxis.z           yaxis.z           zaxis.z          0
-dot(xaxis, cameraPosition)  -dot(yaxis, cameraPosition)  -dot(zaxis, cameraPosition)  1

Especialy take care about zaxis = normal(cameraPosition - cameraTarget) because it is the only difference between RH and LH system.

Save it transposed and that's it

Answer 2

I don't know what is wrong with your code, but it looks different to mine. Here's what I've been using in my projects for the past few years.

    return new float4x4(
        Xax.X, Yax.X, Zax.X, 0,
        Xax.Y, Yax.Y, Zax.Y, 0,
        Xax.Z, Yax.Z, Zax.Z, 0,
        -float3.Dot(pos, Xax), -float3.Dot(pos, Yax), -float3.Dot(pos, Zax), 1
    );

I hope this helps somewhat.