19  Rendering: Initialization and Frame Setup

This tour explores rendering initialization and frame setup in r_main.c, covering R_Init, R_SetupFrame, R_RenderPlayerView, R_SetViewSize, R_ExecuteSetViewSize, and R_AddPointToBox.

19.0.1 R_Init (r_main.c:773–794)

Initializes the renderer: - Sets up data tables (R_InitData, R_InitPointToAngle, R_InitTables) - Applies default view size (R_SetViewSize) - Initializes planes, lights, sky map, translation tables - Resets framecount

19.0.2 R_SetupFrame (r_main.c:829–863)

Prepares per-frame view state: - Assigns viewplayer - Computes viewx, viewy, viewangle (with offset) - Sets extralight, viewz, viewsin, viewcos - Manages fixedcolormap and walllights - Increments framecount and validcount

19.0.3 R_RenderPlayerView (r_main.c:871–898)

Drives the frame render: - Calls R_SetupFrame - Clears segmentation buffers: - R_ClearClipSegs - R_ClearDrawSegs - R_ClearPlanes - R_ClearSprites - Updates network events - Traverses BSP: R_RenderBSPNode - Draws planes: R_DrawPlanes - Renders masked objects: R_DrawMasked - Interleaves with NetUpdate checks

19.0.4 R_SetViewSize (r_main.c:658–665)

Defers view resizing: - Sets setsizeneeded flag - Stores desired block scale and detail shift for the next refresh

19.0.5 R_ExecuteSetViewSize (r_main.c:671–680)

Applies view parameters: - Computes scaledviewwidth, viewheight - Derives detailshift, viewwidth, centerx, centery - Calculates projection: projection = centerxfrac

19.0.6 Rendering Function Selection (r_main.c:702–708)

  • Sets column and span functions:
    • colfunc, basecolfunc, fuzzcolfunc, transcolfunc, spanfunc
  • Based on detailshift (high vs. low detail)

19.0.7 Buffer and Sprite Setup (r_main.c:717–724)

  • Initializes drawing buffer: R_InitBuffer
  • Configures texture mappings: R_InitTextureMapping
  • Sets pspritescale for player sprites

19.0.8 R_AddPointToBox (r_main.c:143–152)

Expands a bounding box to include a point (x, y): - Clamps box edges if the point is outside the current bounds

This completes the walk through of rendering initialization and frame setup in r_main.c.