driedee engine

A Duke Nukem 3D-like game engine which will eventually result in a prototype for a possbily roguelike game.

The progress is visually displayed in this playlist.

To install you need libccore-dev libccfont-dev libccterm-dev libglew-dev libpng12-dev

Pseudocode for renderring using sectors & edges (inspired by the Build Engine and @fabiensanglard his Chocolate Duke Nukem 3D, article):

Scan the sector for bunches to possibly draw

	Create empty stack of linked-edges (bunches)
	Create stack of sectors with the first sector
	while sector stack is not empty:
		for each edge in sector:
			if not facing camera (potentially visible):
				Continue
			if there is a bunch in the stack which shares a vertex:
				Add edge to bunch
			else:
				Create new bunch with this edge
			if portal:
				Add neighbor sector to sector stack
		Pop sector from stack

Sort bunches on distance from player and call draw functions

	while bunch-amount > 0:
		for all bunches defined by the bunch-amount except the first one:
			Compare two bunches by overlap in screen-space perspective
			if no overlap:
				Set other bunch as not closest
			else if this bunch is in front of the other:
				Set oldest bunch-closest flag in temporary buffer as not closest
				Set this one as the closest one

		for all other bunches defined by the bunch-amount:
			if bunch is already not the closest:
				Continue

			Compare two bunches by overlap in screen-space perspective
			if no overlap:
				Set other bunch as not closest
			else if this bunch is in front of the other:
				Set oldest bunch-closest flag in temporary buffer as not closest
				Set this one as the closest one
				Reset for loop (i = 0)

		Call draw function for the closest one
		Decrement bunch-amount
		Put the closest on top of the bunch stack so it won't be iterated over again

Drawing the edges

	Create two arrays for all the highest and lowest drawn pixels for each x value of the screen
	
	Draw function:
		for each edge in bunch:
			if edge is wall:
				Render ceiling if visible
				Render floor if visible
				Render wall if visible
				Mark as occluded in the two arrays
			else if edge is portal:
				Render ceiling if visible
				Render floor if visible
				if next sector's ceiling is lower than this sector's ceiling:
					Render wall between sector heights
				if next sector's floor is higher than this sector's floor:
					Render wall between sector heights
				Update occlusion array according to portal height

Drawing the sprites
	for each sprite:
		Calculate distance from sprite to player
	Sort sprites by distance
	for each sorted sprite:
		Render sprite