Software 3D rendering a cube with Python and SDL2. I ported some javascript code from there: http://www.cores2.com/3D_Tutorial/

gistfile1.py

#!/usr/bin/python2
from math import sin, cos
from sdl2 import SDL_QUIT, SDL_MOUSEMOTION, SDL_MOUSEWHEEL
import sdl2.ext as sdl2ext
from sys import stdout
import time

BLACK = sdl2ext.Color(0, 0, 0)
WHITE = sdl2ext.Color(255, 255, 255)

sdl2ext.init()
CanvasWidth = 800
CanvasHeight = 600
win = sdl2ext.Window("PySDL2 test", size=(CanvasWidth, CanvasHeight))
win.show()
winsurf = win.get_surface()

def line(x0, y0, x1, y1):
    #print "x0:{} y0:{} x1:{} y1:{}".format(x0, y0, x1, y1)
    """draw a line 
    
    http://en.wikipedia.org/wiki/Bresenham%27s_line_algorithm"""
    #sdl2ext.fill(winsurf, BLACK)
    pixelview = sdl2ext.PixelView(winsurf)
    #pixelview[event.motion.y][event.motion.x] = WHITE
    
    # dont draw put of screen
    # this check should be in "while true" loop but for some reason it 
    # didn't work there
    x0 = 0 if x0 < 0 else x0
    x0 = CanvasWidth -1 if x0 >= CanvasWidth else x0
    x1 = 0 if x1 < 0 else x1
    x1 = CanvasWidth -1 if x1 >= CanvasWidth else x1
    y0 = 0 if y0 < 0 else y0
    y0 = CanvasHeight -1 if y0 >= CanvasHeight else y0
    y1 = 0 if y1 < 0 else y1
    y1 = CanvasHeight -1 if y1 >= CanvasHeight else y1
    
    
    dx = abs(x1-x0)
    dy = abs(y1-y0) 
    sx = 1 if (x0 < x1) else -1
    sy = 1 if (y0 < y1) else -1
    err = dx-dy
 
    while True:
        pixelview[y0][x0] = WHITE
        if x0 == x1 and y0 == y1: break
        e2 = 2*err
        if e2 > -dy:
           err = err - dy
           x0  = x0 + sx
        if x0 == x1 and y0 == y1: 
            pixelview[y0][x0] = WHITE
            break
        if e2 < dx: 
            err = err + dx
            y0  =y0 + sy 
   
    del pixelview

def draw_box(CameraPos = {"x": 0, "y": 0, "z": -15}, 
             CameraRot = {"x": 0, "y": 0, "z": 0}):
    """Draws a rotating box, CameraRot variable is presistant if nobody
    outside this function doesn't touch it
    
    http://www.cores2.com/3D_Tutorial/"""
    sdl2ext.fill(winsurf, BLACK) #fill screen with black
    
    # draw a 2D box
    #box={"x0":100,"y0":100, "x1":200, "y1":200}
    #line(box["x0"], box["y0"], box["x0"], box["y1"])
    #line(box["x0"], box["y0"], box["x1"], box["y0"])
    #line(box["x1"], box["y1"], box["x0"], box["y1"])
    #line(box["x1"], box["y1"], box["x1"], box["y0"])
    
    # our 3D model
    CubeVertex = [
        {"x":-1, "y":-1, "z":1},
        {"x":-1, "y":1,  "z":1},
        {"x":1,  "y":1,  "z":1},
        {"x":1,  "y":-1, "z":1},
        {"x":-1, "y":-1, "z":-1},
        {"x":-1, "y":1,  "z":-1},
        {"x":1,  "y":1,  "z":-1},
        {"x":1,  "y":-1, "z":-1},
    ]
    CubeEdges = [
        {"i":0, "j":1},
        {"i":1, "j":2},
        {"i":2, "j":3},
        {"i":3, "j":0},
        
        {"i":4, "j":5},
        {"i":5, "j":6},
        {"i":6, "j":7},
        {"i":7, "j":4},
        
        {"i":0, "j":4},
        {"i":1, "j":5},
        {"i":2, "j":6},
        {"i":3, "j":7},
    ]
    
    
    #CameraPos = {"x": 0, "y": 0, "z": -10};
    #CameraRot = {"x": 0, "y": 0, "z": 0};
    RatioConst = 320
    
    CenterX = CanvasWidth / 2
    CenterY = CanvasHeight / 2
    
    #Rotate camera
    CameraRot["x"] += 0.02
    CameraRot["y"] += 0.02
    CameraRot["z"] += 0.02
    
    PointList = []
    
    for ccv in CubeVertex:
        WorkingVertex = { "x":ccv["x"], "y":ccv["y"], "z":ccv["z"] }
        
        Temp = WorkingVertex["z"]
        WorkingVertex["z"] = -WorkingVertex["x"] * sin(CameraRot["y"]) - WorkingVertex["z"] * cos(CameraRot["y"])
        WorkingVertex["x"] = -WorkingVertex["x"] * cos(CameraRot["y"]) + Temp * sin(CameraRot["y"])
        
        Temp = WorkingVertex["z"]
        WorkingVertex["z"] = -WorkingVertex["y"] * sin(CameraRot["x"]) + WorkingVertex["z"] * cos(CameraRot["x"])
        WorkingVertex["y"] = WorkingVertex["y"] * cos(CameraRot["x"]) + Temp * sin(CameraRot["x"])
        
        Temp = WorkingVertex["x"]
        WorkingVertex["x"] = WorkingVertex["x"] * cos(CameraRot["z"]) - WorkingVertex["y"] * sin(CameraRot["z"])
        WorkingVertex["y"] = WorkingVertex["y"] * cos(CameraRot["z"]) + Temp * sin(CameraRot["z"])
        
        WorkingVertex["x"] -= CameraPos["x"];
        WorkingVertex["y"] -= CameraPos["y"];
        WorkingVertex["z"] -= CameraPos["z"];
        
        # Convert from x,y,z to x,y
        # This is called a projection transform
        # We are projecting from 3D back to 2D
        ScreenX = (RatioConst * (WorkingVertex["x"])) / WorkingVertex["z"];
        ScreenY = (RatioConst * (WorkingVertex["y"])) / WorkingVertex["z"];
        
        # Save this on-screen position to render the line locations
        PointList.append({"x":int(CenterX + ScreenX), "y":int(CenterY + ScreenY)})
        
    for cce in CubeEdges:
        # Find the two points we are working on
        Point1 = PointList[cce["i"]];
        Point2 = PointList[cce["j"]];
        
        # Render the edge by looking up our vertex list
        line(Point1["x"], Point1["y"], Point2["x"], Point2["y"]);
        

draw_box() 
running = True
lastm=(0,0) #last mouse position
CameraPos = {"x": 0, "y": 0, "z": -5}
CameraRot = {"x": 0, "y": 0, "z": 0}
print "hold down mouse button to move camera"
print "use scroll wheel to change how far camera is"
fps=0
while running:
    t = time.time()
    events = sdl2ext.get_events()
    for event in events:
        if event.type == SDL_QUIT:
            running = False
            break
        if event.type == SDL_MOUSEMOTION:
            if event.motion.state == 1:# 1st mouse button is down
                # paint a line
                #line(lastm[0], lastm[1], event.motion.x, event.motion.y)
                
                # change camera pos
                mouse_sens = 50.0 # mouse sensitivity
                CameraPos["x"] = (event.motion.x - CanvasHeight / 2)/ mouse_sens
                CameraPos["y"] = (event.motion.y - CanvasWidth / 2)/ mouse_sens
                lastm=event.motion.x, event.motion.y
            else: #no buttons pressed
                lastm=event.motion.x, event.motion.y
                
        elif event.type == SDL_MOUSEWHEEL:
            # change how far camera is 
            CameraPos["z"] += event.motion.x 
    print "fps:", fps, " CameraPos:", CameraPos, "\r",
    stdout.flush()
    draw_box(CameraPos=CameraPos)
    win.refresh()
    fps = 1000 / int((time.time() - t)*1000)
sdl2ext.quit()
print # make a empty line