Delta Force 2 Hardware Renderer

[edbarber]

In Delta Force 2 the 3D objects such as buildings and trees are visible through the terrain. This appears to not be the case many years ago as shown in this video https://youtu.be/kG8cOEVP3Vc. I also remember this game working fine on my Nvidia GeForce 7600 GS on Windows XP back in the day with the correct drivers. Last I remember, the driver was likely released around June 2008. It looks like the game is feeding the GPU wrong depth values for the terrain, causing the 3D objects to overlap. Perhaps it maybe possible to wrap the Z-buffer values in a way that is compatible on modern GPUs like the Nvidia GeForce RTX 3070.

[elishacloud]

I wonder if this is a shadow map issue. #75

[edbarber]

This forum adds more depth to the problem https://www.vogons.org/viewtopic.php?t=52136. dgVoodoo 2 fixes the shadow buffer issues in the first 2 Splinter Cell games but the creator of dgVoodoo attempted to fix Delta Force 2 to some avail. After digging around I believe that the way the engine calculates the depth values for the voxels before passing it to Direct3D is done in a very specific way (not in Direct3D traditional ways) that is compatible with video cards released during Delta Force's 2 development. Specifically the Nvidia TNT cards or the ATI Rage 128 cards.

[elishacloud]

I believe that the way the engine calculates the depth values for the voxels before passing it to Direct3D is done in a very specific way (not in Direct3D traditional ways) that is compatible with video cards released during Delta Force's 2 development.

If that is the case it could be related to Revenant, which also has depth value issues: #107

[edbarber]

I was able to somewhat mitigate this issue by using DDrawCompat. Changing the Z-buffer depth to 32-bit will fix the models showing through the UI. Editing the Hw dll file will let me adjust the normalizing coefficient that controls how the voxel depth value scales. It seems like either the terrain will always be visible through the 3D models or the opposite.

Dege's edit to the same dll aligns the water with the terrain perfectly but for some reason some of the voxels show through the water.

This seems like an issue with various chipsets not longer after the game's launch too.
https://youtu.be/nXmrP29WSuM?si=aO5ihOjttqV6BH6N

Without reworking parts of the dll file and/or the the game's main exe, it seems the only way to fix this is by emulating whatever Nvidia did in their drivers to force the game to render correctly like in this video: https://youtu.be/kG8cOEVP3Vc

[elishacloud]

Changing the Z-buffer depth to 32-bit will fix the models showing through the UI.

You can do this with dd7to9 using the DdrawOverrideStencilFormat and setting it to 75.

Editing the Hw dll file will let me adjust the normalizing coefficient that controls how the voxel depth value scales.

You could also try setting DdrawClampVertexZDepth to 2. This fixes depth value issues with some games.

Furthermore, you could adjust the DepthBiasFactor and the DepthBiasDropOffValue. The DepthBiasFactor could be any float value. This value gets multiples by the DepthBias render state. Some games like Freelancer requires this.

For DepthBiasDropOffValue you can use any float value. When the game sets a value that is smaller than this value it is dopped (or turned to 0.0f). Since DX7/8 use ZBIAS rather than DepthBias it is converted to DepthBias. Since the game uses a 16bit buffer the smallest value is around 0.00001526. So setting the cutoff to this value will basically drop all values where the game sets the ZBIAS to 1. Silent Hill 2 requires this on Nvidia graphics cards.

[edbarber]

Changing the Z-buffer depth to 32-bit will fix the models showing through the UI.

You can do this with dd7to9 using the DdrawOverrideStencilFormat and setting it to 75.

Editing the Hw dll file will let me adjust the normalizing coefficient that controls how the voxel depth value scales.

You could also try setting DdrawClampVertexZDepth to 2. This fixes depth value issues with some games.

Furthermore, you could adjust the DepthBiasFactor and the DepthBiasDropOffValue. The DepthBiasFactor could be any float value. This value gets multiples by the DepthBias render state. Some games like Freelancer requires this.

For DepthBiasDropOffValue you can use any float value. When the game sets a value that is smaller than this value it is dopped (or turned to 0.0f). Since DX7/8 use ZBIAS rather than DepthBias it is converted to DepthBias. Since the game uses a 16bit buffer the smallest value is around 0.00001526. So setting the cutoff to this value will basically drop all values where the game sets the ZBIAS to 1. Silent Hill 2 requires this on Nvidia graphics cards.

None of these adjustments had any effect. Also, the same adjustments to the Hw dll file made the game more broken with the DxWrapper. 😕

[elishacloud]

According to Dege:

This game has a voxel based software terrain renderer. The main problem for most hw I guess is that this game write the rendered terrain and its depth values to the back- and Z-buffer by the CPU, prior to rendering objects by D3D.

If that is the case it sounds similar to Revenant. I need to spend some time to work on this. dxwrapper doesn't handle zbuffer reads, writes or copies very good.