The ray tracing aspect of my program works by storing triangle objects in a vector
called world. It then passes the world to the render function, which can use
either orthographic of perspective views. A camera is created, and rays from the camera
are passed to the intersectTriangle function along with the world, in order to find
intersections. The closest triangle is found, and the color of that intersection pixel is computed
using a combination of Phong shading, and base color calculation from textures.
Texture and lighting calculations are made by the FetchColor and Texture classes.
FetchColor has a method for calculating Phong shading based on the light position, intersection
position, and camera vector origin. It combines ambient, diffuse, and specular shading. Phong shading is always
applied after the calculation of the base color. Another method in FetchColor, getBaseColorBary, calculates a base
color values using Barycentric coordinates, and vertex color values.
Finally, the other methods in FetchColor rely on the Texture class, which I used for procedural texture generation.
The Texture class works by generating an array of random numbers with values between 0 and 1.
Although 1 dimensional, the array also works for 2 dimensional grids of random
numbers by setting the array length to the grid width squared (for a square grid), and using, "row * width + column"
to access grid positions. The lerp method performs linear interpolation given two values, and
the fraction of the way from one to the other. The method sample1DTexture
is used to sample noise along one axis. The method sample2DTexture is used to
sample noise across 2 dimensions. Both sampling methods use a combination of linear interpolation,
and smoothing with the cosine function to generate gradients between random values.
The FetchColor class utilizes
the Texture class in a number of ways. Its method get1DTextureColor uses one dimensional samples
to generate color gradients in the x, y, and z directions. The method get2DFractalSumColor can be used
for a variety of purposes. A simple 2D noise texture with linear interpolation and smoothing can be generated
by setting the number of layers to 1. Adding additional layers allows for fractal patterns with decreasing scale.
The parameter turbulence can be set to true to achieve a smokey effect, which works by shifting the noise function
down, scaling it, and taking the absolute value. The wood parameter can be set to true to achieve a topographic result by multiplying the function
by 10, and getting the decimal value left after subtracting its integer portion. Results can be further tweaked
by changing some other variables:
- baseScale: The starting scale of the noise function. Higher values correspond to zooming out on the function.
- offset: Sets one's reference point on the function. Can be changed to view different portions of the noise function.
- baseAmp: Starting amplitude. An amplitude of 1 gives color values between 0 and 255 when using a single layer.
- scaleMultiplier: Reduces scale by this factor for each layer.
- ampMultiplier: Reduces amplitude by this factor for each layer, so you may want to use a high baseScale for layering.
See pdf, and SavedImages.zip for examples of textures generated.