WoD Depth Buffer/3D clipping madness

[Master674]

Hey everyone!

Since patch 6.0 hit last week, I started working on WoW again and I encountered something that's quite strange.
When I draw 3D objects with clipping, they're kinda broken now. The clipping only looks okay when my camera is zoomed in. When I zoom out my camera, all objects start to disappear behind the terrain.

Okay: https://i.imgur.com/ZEKBXIu.jpg
Not okay (slightly zoomed out): https://i.imgur.com/gNNjfBa.jpg

My near clip and far clip values are taken from World::GetNearClip & World::GetFarClip. Viewport Depth is still constant 0.94f.
The depth target is taken from a hook in CWorldSceneRender::Render; it's the depth buffer that the game uses to draw the world.

The projection matrix that I use is taken from GxuXformCreateProjection_Exact (0x77A89; 19034), which looks like this:

static Matrix PerspectiveFovWoW(float fovy, float aspect, float zn, float zf) {
    float xs = tanf(fovy * 0.5f) * zn;
    float xn = zn / (xs * aspect);

    Matrix mat = {
          xn,    0.0f,                            0.0f,  0.0f,
        0.0f, zn / xs,                            0.0f,  0.0f,
        0.0f,    0.0f,           (zn + zf) / (zf - zn),  1.0f,
        0.0f,    0.0f, ((zf * -2.0f) * zn) / (zf - zn),  0.0f
    };

    return mat;
}

The look at matrix for WoW's coordinate system looks like:

static Matrix LookAtWoW(const Vector3 &eye, const Vector3 &at, const Vector3 &up) {
    Vector3 zaxis = (at - eye).normalize();
    Vector3 xaxis = Vector3::Cross(zaxis, up).normalize();
    Vector3 yaxis = Vector3::Cross(xaxis, zaxis);

    Matrix mat = {
                xaxis.x,         yaxis.x,         zaxis.x, 0.0f,
                xaxis.y,         yaxis.y,         zaxis.y, 0.0f,
                xaxis.z,         yaxis.z,         zaxis.z, 0.0f,
        -xaxis.dot(eye), -yaxis.dot(eye), -zaxis.dot(eye), 1.0f
    };

    return mat;
}

GetNearClip/GetFarClip offsets:

uintptr_t GetNearClip = 0x4F847C; // 19034
uintptr_t GetFarClip = 0x4F8452; // 19034

Camera offsets:

struct CameraHolder {
    struct VMTHolder {
        uint32_t FOV = 0;
        uint32_t Forward = 1;
        uint32_t Right = 2;
        uint32_t Up = 3;
    } VMT;

    uintptr_t Position = 0x8;
} CGCamera;

I was wondering if anyone of you guys did anything drawing related since MoP/WoD and if you have similar issues.
Without Z-testing everything looks fine ofcourse.

Thanks

[namreeb]

It is very, very early here, so I may be missing something obvious, but I don't see the problem?

[Master674]

It is very, very early here, so I may be missing something obvious, but I don't see the problem?

Take a look at the second screenshot. If I zoom out with the camera the white circle below my character completely disappears "behind" the terrain. In the second screenshot it's already half behind the terrain when it should actually be at the character position.

[Master674]

The issue is in GxuXformCreateProjection. I've adjusted this projection matrix a little and it seems to work now.

Feel free to use it:

static Matrix PerspectiveFov(float fovy, float aspect, float zn, float zf) {
    float ys = 1.0f / tanf(fovy / 2.0f);
    float xs = ys / aspect;

    Matrix mat = {
          xs,  0.0f,                 0.0f,  0.0f,
        0.0f,    ys,                 0.0f,  0.0f,
        0.0f,  0.0f,       zf / (zf - zn),  1.0f,
        0.0f,  0.0f, -zn * zf / (zf - zn),  0.0f
    };

    return mat;
}