Render modes
These are all the rendering modes present in Source.
Normal
This is the normal rendering mode.
Setting the FX Amount (0 - 255) keyvalue will have no effect on entities rendered with in this mode.
This mode is not recommended for sprites. (Will not render sprite alpha transparency.)
Color
This mode is not recommended for sprites. (Will not render sprite alpha transparency.)
Texture
Works exactly like the Color rendering mode.
This mode is not recommended for sprites. (Will not render sprite alpha transparency.)
Glow
This render mode is intended for glow sprites. (It will not make entities glow in the dark - sprites will always glow in the dark.) This mode renders sprite alpha transparency correctly, making it one of the few ideal rendering modes for sprites.
Solid (Obsolete)
This rendering mode is also referred to as Alphatest.
Alphatesting is the process of comparing each pixel of the texture(s), rendering pixels of a certain shade of blue (seen in debug/debugluxels
) as transparent.
This is very useful for rendering see-through grates, bars and fences, that would otherwise require a complex and detailed brushwork to accomplish, using just a single texture.
While this rendering mode was required to alphatest textures in Goldsource, alphatesting is now (in Source) handled automatically by materials, making this rendering mode obsolete.
This mode is not recommended for sprites. (Will not render sprite alpha transparency.)
Additive
The precise formula is: <math>...</math>(?)
This mode renders sprite alpha transparency correctly, making it one of the few rendering modes for sprites. However, as it still tests the Z buffer, rendering sprites as thin layers that will penetrate any surrounding brushwork, it is not ideal for this.

Additive Fractional Frame
Blends between animation frames.
This mode renders sprite alpha transparency correctly, making it one of the few rendering modes for sprites.
Alpha Add
This rendering mode is not in the FGD, but can be achieved through turning SmartEdit off and then giving the rendermode field the value of 8
.
This mode is not recommended for sprites. (Will not render sprite alpha transparency.)
World Space Glow
This mode renders sprite alpha transparency correctly, making it one of the few ideal rendering modes for sprites. It has no Z buffer checks, so it's much like the #Glow mode, except that it is rendered like it has a place in the world, it's size being relative to the world rather than the screen.
This effect is most useful for having lamp props (like bulbs) glow properly.
Dont Render
This rendering mode is also referred to as None.
This rendering mode simply tells the renderer not to render this entity. (The player can still interact with the entity, but it will be 100% transparent.)
rendermode 6
.This is useful for completely invisible entities. You could for instance hide button tool brushes used for interaction with an underlying button model.