R_PrecacheLevel Preloads all relevant graphics for the level.

R_ProjectSprite Generates a vissprite for a thing if it might be visible.

RenderBSPNode Renders all subsectors below a given node, traversing subtree recursively. Just call with BSP root.

R_RenderView

R_RenderSegLoop Draws zero, one, or two textures (and possibly a masked texture) for walls. Can draw or mark the starting pixel of floor and ceiling t

R_SetupFrame

R_SortVisSprites

This is a not-very-pretty routine which handles the face states and their timing. the precedence of expressions is: dead > evil grin > turned head > s

A fairly efficient way to draw a number based on differences from the old number. Note: worth the trouble?

Initializes sound stuff, including volume Sets channels, SFX and music volume, allocates channel buffer, sets S_sfx lookup.

Stop and resume music, during game PAUSE.

Per level startup code. Kills playing sounds at start of level, determines music if any, changes music.

Updates music & sounds

S_getChannel : If none available, return -1. Otherwise channel #.

TryRunTics

V_DrawBlock Draw a linear block of pixels into the view buffer.

V_DrawPatchFlipped Masks a column based masked pic to the screen. Flips horizontally, e.g. to mirror face.

V_Init

Updates stuff each tick

W_AddFile All files are optional, but at least one file must be found (PWAD, if all required lumps are present). Files with a .wad extension are wadli

W_Reload Flushes any of the reloadable lumps in memory and reloads the directory.

WritePCXfile

Z_CheckHeap

Z_FreeTags

Z_Init

This function adds a sound to the list of currently active sounds, which is maintained as a given number (eight, usually) of internal channels. Return

This function loads the sound data from the WAD lump, for single sound.

Calculates the slope and slope according to the x-axis of a line segment in map coordinates (with the upright y-axis n' all) so that it can be used wi

A_BFGSpray Spawn a BFG explosion on every monster in view

A_BFGsound

A_BossDeath Possibly trigger special effects if on first boss level