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Glide vs. Direct3D


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Glide versus Direct3D

Excerpt from F-22_Install_Decision_Aid.mht, included in the TAW 2008 installation.

Glide versus Direct3D: Which renderer suspends your disbelief?

This is the big decision for your install (but don’t worry; you can always change your mind later), and why this guide was written. The following sections compare the relative strengths and weaknesses of both renderers in the major categories.

Resolution:

The winner in this category is based on your personal preference.

Glide supports up to 800x600 native resolution, but with the included Glide wrapper the program can be forced to render at whatever your graphics card can support. Textures and fonts will remain at 800x600, but 3D objects are rendered at the resolution you select. Depending on your video card, higher resolutions may incur a FPS penalty due to the increased workload of the Glide wrapper. Additionally, since the Glide wrapper actually renders in Direct3D (DirectX7 or DirectX9, selectable), you can force hardware-based enhancements such as anti-aliasing (multisampling, supersampling, or combinations), anisotropic filtering, image quality, LOD bias clamping, etc. on top of your Glide rendering.

Direct3D under normal circumstances supports up to 800x600, but there is a hex-edited exe that allows for a fixed resolution of 1024x768. However, the options menu cannot be accessed from within the program while the 1024x768 resolution is enabled. A command line utility has been included with the 1024x768 executable to allow for configuration. The current 1024x768 version has been improved over past versions by correcting graphic artifacts that were once present in the zoomed IRST view.

image001.jpg

Direct3D in 1024x768 resolution. This is the ideal resolution for a 4:3 monitor.

Aspect Ratio:

Due to the default resolution of the original game, the aspect ratio at 800x600 appears stretched top to bottom on a 4:3 monitor, but looks proportionally correct on a widescreen monitor. As demonstrated in the previous screenshot, 1024x768 is ideal for a 4:3 monitor. If you have a widescreen monitor, I recommend using one of the 800x600 versions. Running in Glide mode and forcing your widescreen monitor’s native resolution is particularly effective, as the following screenshot demonstrates.

image002.jpg

Glide upscaled to 1440x900. 800x600 native resolution is ideal for widescreen monitors.

Terrain and Haze Effects:

Glide is given the edge here due to improved haze and better terrain texture smoothing, but the difference is slight and highly subjective. All screenshots were done at 800x600 for comparative consistency. The following screenshots are Glide and D3D terrain renders, respectively.

image003.jpg

Glide Terrain and Haze

image004.jpg

Direct3D Terrain and Haze

Lighting Effects:

Direct3D beats out Glide here, hands down. The AGP textures allow for enhanced and colored lighting with D3D, while the Glide renderer is limited to white. The following are comparisons of Glide and D3D lighting effects:

image006.jpgimage008.jpg

Glide and D3D Lighting Effects: AA Missiles

image010.jpgimage012.jpg

Glide and D3D Lighting Effects: AG Rockets

image014.jpgimage016.jpg

Glide and D3D Lighting Effects: Air Target Explosions

image018.jpgimage020.jpg

Glide and D3D Lighting Effects: Ground Target Explosions

Artifacts and Bugs:

Glide soundly beats D3D in this category, primarily because newer video hardware and more recent versions of DirectX make data calls differently now than in 1998. Since the Glide renderer doesn’t use AGP, it is not subject to these incompatibilities.

There are two specific large issues and one small issue with D3D rendering. The first issue is a corrupted view in the zoomed in Moving Map MFD. This first image (in Glide mode) shows how the moving map should look:

image022.jpg

Moving Map in Glide

The following is how the map is rendered in D3D mode on modern video hardware (i.e. video cards from the past eight years):

image024.jpg

Moving Map in D3D (on modern cards)

Likewise, the SmartView system (the F12 view) causes system lockups or CTDs in D3D mode, but not in Glide mode. Even if you don’t use the F12 view, often the game will default to the view upon player “death”. There is a workaround in DirectX that will permit the use of the F12 view in D3D, which is detailed in the FAQ and in the Known Issues thread.

Lastly, there is a known issue with Direct3D rendering when Light Sourcing is enabled from the options menu. When light sourcing is selected, lines where separate textures meet show as transparencies. This occurs on 3D objects (such as the aircraft) as well as in scenery. The following are screenshots of the F-22 and its surrounding terrain rendered in Glide (note that all screenshots are done at 800x600 using the original 1998 aircraft textures for a consistent baseline comparison):

GlideLightSourceNoSeams.jpg

GlideNoBanding.jpg

And in Direct3D:

D3DLightSourceSeams.jpg

Note that the seam is highlighted in the following image, as it is difficult to see in a still shot.

D3DCyanBanding.jpg

Mod Support:

I have to give Glide the edge here, primarily because the NVG mod is much more robust in Glide than in D3D. This is a direct result of the AGP textures, and enhancements made to D3D support by modifying the executable rather than datafiles. The bottom line is that any graphical enhancements will be fully supported in Glide mode, but may require tweaking for use in D3D. The following screenshot is the new Full Moon NVG palette in Glide mode:

image025.jpg

New Full Moon NVG Palette rendered in Glide

And here is the same mod in D3D, with a palette workaround to allow for the green hue from the AGP calls:

image027.jpg

New NVG Palette (modified to accomodate Green AGP hue) in D3D

Oh, and in case you were wondering, the F-22 Promotional Video was rendered in Glide (1600x1200), then downscaled to 720x480 for streaming.

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