Rasterized Toy Renderer

A very simple software renderer using single-threaded CPU rasterization, and outputting result as ASCII art to stdout. Some 3D models are "transpiled" from wavefront object to C header files using code stolen from olive.c, because I didn't want to lose time dealing with files at the start of this project. This is just a toy project, don't expect good performance or usability.

I got the idea to do such a project from olive.c. Check it out!

Requirements:

Only a standard C compiler, and either Windows or a POSIX-compliant operating system.

Output:

By default, it produces images like this:

                                        p
                                    $RPYF       Ax!m    dD&QKKZY
                                      p8NRKKKXH8NN$$8UQ5/
                                     XmHHmDW@&&QQQMM$88U
                                 9bAHRN@@@@@@@&&&QQMM$$mbh
                              tbX00WN%%&&&@@@@@&%%QQ000#HXO    b
                             POXDggNN%%%&&&@@@@@%%%WWW0gDRKd Vgq
                             POXDggNNN%Q&&&&&&&&&%%QNNMBBmmOMS
                 16BQQ8      PpKRRggNNQQQ&%%&&%%%%WWWgggRROh
                     #&0p    qVARRBBMMMQQW%%%QQQQWWN00$mKdx|
                      uQ@Q00Mw4A88$$$00WNNQQNNWWMMM#DDOkEo
                        HNN@@]hGGHH##gBBMMB000###AAAhaxC!
      999$$$$0000K        Tqw}PPpKbHHHDDHRRRAAAddEZZ{iH
    //999$$$$000KK=            jkk44hhhpqq6aaZZ1f[R
    S##GGGMMMQ8eee=               //vvCvvJ)}h2
     Sbbbbpppppeee
      5999p%%%kii
        999k55ir
          RRHH

Usefull macros

Graphics engine: (rasterm.h)

• RASTERM_IMPLEMENTATION : turns the header into a source file
• ASPECT_RATIO=[float] : changes the aspect ratio of the render (controls the width indirectly, TODO: move iot to renderer)
• FAST_MATH: use fast inverse square root algorithm (might not be actually faster on modern hardware)
• PERSPECTIVE_UV enables perspective-corrected uv mapping on 3D triangles (enabled by default in main.c)

Renderer: (main.c)

• HEIGHT=[int] : change size of canvas (default value:64)
• PX_ASPECT=[float] : to adapt to the "aspect ratio" of the display's pixels (default 2.21 for terminal font) (controls the width indirectly)
• WIDTH=[int]: I advise not using this one, you should rather use ASPECT_RATIO="(float)[int]/HEIGHT", or you will have to deal with the pixel aspect ratio too
• FRAMES=[n] : Draws n consecutive animated frames (recommended) (default: 1, ignored when using RENDER_TARGET=GDI)
• RENDER_TARGET=[GRAYSCALE|COLOR|FULL_COLOR|GDI(WINDOWS ONLY)]: Change output mode (default: GRAYSCALE) (when using gdi, please link with gdi32)
• STEP_RENDER : Refreshes the display after each triangle drawn on canvas (looks cool, but is very slow)
• FPS (GDI only): number of frames to be displayed per second. (defaults to 60)
• TEXTURED: display the teapot uv-mapped with ./texture1.png.
• SHADOWMAP_DEMO: renders a shadowmap, and add shadows to the table
• SHADOW_RES=[int]: resolution of the shadowmap (square) (defaults to 256)

Display lib: (printImg.h)

• DITHER : enables dithering for full color terminal rendering

Build procedure:

To compile with de default config, you only need to link with libmath:

[your c compiler] -o threed main.c -lm
./threed

If you want to change the settings, if your compiler supports it, you could define the config macros with compilation flags. For example for a sequence of 500 dithered full color "high resolution" 16/9 images, you can try:

[your c compiler] -o threed main.c -lm -DHEIGHT=128 -DASPECT_RATIO="16./9." -DFRAMES=500 -DRENDER_TARGET=FULL_COLOR -DDITHER
./threed

To compile for GDI target on windows:

[your c compiler] -o window main.c -lm -lgdi32 -DHEIGHT=720 -DASPECT_RATIO="16./9." -DRENDER_TARGET=GDI -O3
./window

Architecture:

The code is split in 3 parts:

• The renderer: located in main.c.
• The graphics engine : located in rasterm.h. It is the core of this project.
• The terminal output library: located in printImg.h. It is in charge of displaying the rendered images to the terminal.
• The Wavefront .obj parser: located in parseObj.c.

rasterm.h

This is the most important file of this repo. It is a STB-style library that contains the necessary tools for rasterizing and shading 3D triangles to a 2D buffer.