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I begin to learn graphic programming on directx12. I try to make a camera wich can move dans rotate around the world.

I take this code as a basis: https://www.braynzarsoft.net/viewtutorial/q16390-transformations-and-world-view-projection-space-matrices

I try lot of method, but every time I finish on the same problem, my camera move and can rotate (on Y only for the moment). But when I move after the control still relative to my basis orientation than my new one.

I dunno if it come from how I handle movement (During waiting answer I will try to make my movement base on a target vector) Or how I multiply martix.

This is the actual point of my code. I use this source to not use LookAtLH(): https://www.3dgep.com/understanding-the-view-matrix/

void UpdateCamera() {

    XMVECTOR cUp = XMLoadFloat4(&cameraUp);

    if (GetAsyncKeyState('Z')) {

        cameraPosition.y += 0.001f;

    }
    else if (GetAsyncKeyState('S')) {
        cameraPosition.y -= 0.001f;
    }

    if (GetAsyncKeyState('Q')) {
        cameraPosition.x -= 0.001f;
    }
    else if (GetAsyncKeyState('D')) {
        cameraPosition.x += 0.001f;
    }
    if (GetAsyncKeyState('A')) {
        rotation += 0.0001f;

    }
    else if (GetAsyncKeyState('E')) {
        rotation -= 0.0001f;
    }

   if (GetAsyncKeyState('P')) {
        cameraPosition.z += 0.001f;

   }
    else if (GetAsyncKeyState('M')) {
        cameraPosition.z -= 0.001f;

    }
    XMMATRIX translationMat =     XMMatrixTranslationFromVector(XMLoadFloat4(&cameraPosition));
    /* XMMATRIX rotYMat = XMMatrixRotationAxis(cUp, rotation);*/

    float cosPitch = cos(0.0f);
    float sinPitch = sin(0.0f);
    float cosYaw = cos(rotation);
    float sinYaw = sin(rotation);

    XMFLOAT3 xaxis = { cosYaw, 0, -sinYaw };
    XMFLOAT3 yaxis = { sinYaw * sinPitch, cosPitch, cosYaw * sinPitch };
    XMFLOAT3 zaxis = { sinYaw * cosPitch, -sinPitch, cosPitch * cosYaw };

    XMVECTOR eye = XMLoadFloat4(&cameraPosition);


// Create a 4x4 view matrix from the right, up, forward and eye position vectors
    XMMATRIX viewMatrix = {
        xaxis.x,yaxis.x,zaxis.x,0.0f,
        xaxis.y,yaxis.y,zaxis.y,0.0f,
        xaxis.z,yaxis.z,zaxis.z,00.0f,
        -XMVectorGetX(XMVector3Dot(XMLoadFloat3(&xaxis), eye)), -XMVectorGetX(XMVector3Dot(XMLoadFloat3(&yaxis), eye)), -XMVectorGetX(XMVector3Dot(XMLoadFloat3(&zaxis), eye)), 1.0f
    };


    XMStoreFloat4x4(&cameraViewMat, viewMatrix);// XMMatrixInverse(nullptr, translationMat * rotXMat));


}

void Update()
{

    UpdateCamera();
     ///....

}
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1 Answer 1

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My hint was good, it's come from how I do the position update. There is the correct code. By this way I can keep the local coordonate with cUp, cTarg and cPos

void UpdateCamera() {

    // Get Datas
    XMMATRIX viewMatrix = XMLoadFloat4x4(&cameraViewMat);

    //Move Up and bottom
    if (GetAsyncKeyState('Z')) {
        viewMatrix *= XMMatrixTranslation(0.0f,-0.0001f,0.0f);
    }
    else if (GetAsyncKeyState('S')) {
        viewMatrix *= XMMatrixTranslation(0.0f, 0.0001f, 0.0f);
    }

    //Move Right and Left
    if (GetAsyncKeyState('Q')) {
        viewMatrix *= XMMatrixTranslation(0.0001f, 0.0f, 0.0f);
    }
    else if (GetAsyncKeyState('D')) {
        viewMatrix *= XMMatrixTranslation(-0.0001f, 0.0f, 0.0f);
    }

    //Move forward/Backward
    if (GetAsyncKeyState('P')) {
        viewMatrix *= XMMatrixTranslation(0.0f, 0.0f, -0.0001f);
    }
    else if (GetAsyncKeyState('M')) {
        viewMatrix *= XMMatrixTranslation(0.0f, 0.0f, 0.0001f);
    }

    //Rotate Y axis
    if (GetAsyncKeyState('A')) {
        viewMatrix *= XMMatrixRotationY(0.0001f);
    }
    else if (GetAsyncKeyState('E')) {
        viewMatrix *= XMMatrixRotationY(-0.0001f);
    }

    //Rotate X axis
    if (GetAsyncKeyState('R')) {
        viewMatrix *= XMMatrixRotationX(0.0001f);
    }
    else if (GetAsyncKeyState('T')) {
        viewMatrix *= XMMatrixRotationX(-0.0001f);
    }

    //Rotate Z axis
    if (GetAsyncKeyState('F')) {
        viewMatrix *= XMMatrixRotationZ(0.0001f);
    }
    else if (GetAsyncKeyState('G')) {
        viewMatrix *= XMMatrixRotationZ(-0.0001f);
    }

    //Update View Matrix of Camera
    XMStoreFloat4x4(&cameraViewMat, viewMatrix);
}

Link to the project : https://github.com/Zeldarck/TrainingDx12

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