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Sunday, August 14, 2011

Introducing SRT

A few weeks ago I finished an early version of a ray tracer written in completely standard ANSI C.  I undertook this small project for a number of reasons.  It dawned on me that most of the work I had been doing involved an environment with an IDE and an object oriented language.  While this isn't an inherently bad thing, it is healthy to stay proficient in as many paradigms as possible.  Therefore, I decided I was going to do a project in straight C with MinGW and Notepad++ to remind myself that you can do everything without polymorphism, inheritance, and encapsulation.  The end goal was a simple raytracer with an interface that mimicked Open GL.  Since I decided to use SDL for software pixel operations I decided to call the project SRT, for "SDL Ray Tracer."  The acronym is just as viable for "Simple Ray Tracer."  Feel free to browse the project in its early form on Google Code at the link below.  Hopefully the project will be seen on GitHub someday too.

Basic features of SRT include the following:
  • Raycasting support for multiple shapes, including spheres, 3D planar polygons, and oriented bounding boxes (OBBs)
  • Support for typical 3D transformations, vector, and matrix operations.  The "Projection" and "ModelView" matrices can be translated, rotated, and scaled.
  • Material and lighting support, with full RGBA channels for ambient, diffuse, and specular colors.  Materials also include scalar values for reflectivity and transmission (transparency).  Phong illumination included by default.
  • Optional support for super sampling, control over recursive depth and other parameters for scene lighting.
  • Although only tested on Windows, should support all the platforms and resolutions that SDL supports.
  • Typedefs and macros provide support for single or double floating point precision, and assertions which can be omitted from "release" code.
  • Future releases will hopefully support multiple light sources, orthographic projections, manipulation of the matrix stack, texture mapping, and thread support.
A typical program for SRT might resemble the following.  Note the resemblance to a typical Open GL program.
-- Init Function --
srtCreateWindow(800, 600, "SRT: SDL Ray Tracer");
srtPerspective(45.0, 800.0 / 600.0, 1.0);

-- Draw Function--
/* clear buffer */
srtClearColor3(0.05f, 0.05f, 0.05f);

/* move camera 4.5 units backs */
srtTranslate(0.0, 0.0, 4.5);

/* load identity modelview */

/* setup a light */
srtLightAmbient4(0.065f, 0.065f, 0.065f, 0.15f);
srtLightDiffuse4(0.35, 0.35, 0.35, 0.35);
srtLightSpecular4(0.25, 0.25, 0.25, 0.85);
srtLightPosition3(-1.0, 1.1, -0.75);

/* setup a material */
srtMatAmbient4(1.0, 0.0, 0.0, 1.0);
srtMatDiffuse4(0.45, 0.45, 0.45, 0.75);
srtMatSpecular4(0.3, 0.3, 0.3, 0.35);

/* sphere: x, y, z, radius */
srtCreateSphere4(1.1, -0.85, -4.5, 0.65);

/* finish the scene */