draw.cpp File Reference

#include "../include/all.hpp"
#include <cmath>
#include <algorithm>
#include <climits>
#include <random>
#include <omp.h>

Macros
#define	EPSILON   0.001

Functions
void	render (Image &img)
	The render function that loops over the screen of pixels. More...
RGBA	shootPrimaryRay (double x, double y)
	Shoots a primary ray into the scene, at pixel location (x,y). More...
ObjectInfo	hitNearest (Ray &ray)
	Gets the nearest object in the path of the ray. More...
ObjectInfo	hitMiss ()
	Does nothing. More...
RGBA	diffuseLight (const ObjectInfo &obj)
	Get the diffuse light color,with shadow checking. More...
RGBA	reflectionLight (const Ray &ray, const ObjectInfo &obj)
	Get the reflection light color. More...
RGBA	refractionLight (const Ray &ray, const ObjectInfo &obj)
	Get the refraction light color. More...
RGBA	globalIllumination (const ObjectInfo &obj, int gi_bounce)
	Get the global illumination light color. More...
ObjectInfo	checkPlane (Ray &ray, bool exit_early)
	Check if any planes are intersecting with the ray. More...
RGBA	getColorSun (double lambert, RGB objColor, RGB lightColor)
	Get the Color of Sun (directional light) More...
RGBA	getColorBulb (double lambert, RGB objColor, RGB lightColor, double t)
	Get the Color of Bulb (scene light) More...

Detailed Description

Author

Jin (jinj2.nosp@m.@ill.nosp@m.inois.nosp@m..edu)

Version

0.1

Date

2024-11-07

Copyright

Copyright (c) 2024

Function Documentation

checkPlane()

ObjectInfo checkPlane	(	Ray &	ray,
		bool	exit_early
	)

Check if any planes are intersecting with the ray.

Parameters

ray	The ray to check against.
exit_early	For shadow checking purposes, exit early if a plane is in the way, casting shadows. Do not set to true with bulb(light in scene).

Returns

ObjectInfo The objectInfo instance which contains all intersection informations.

The parametric distance t is calculated. If t < 0, this means that the ray intersection is behind the ray origin, which means no intersection. Else, calculate the intersection point with t.

diffuseLight()

RGBA diffuseLight

(

const ObjectInfo &

obj

)

Get the diffuse light color,with shadow checking.

Parameters

obj	The objectInfo instance with the intersection information.

Returns

RGBA The RGBA linear color at the location.

The diffuse light color is checked by creating a shadow ray from the intersection point and the normal. This ray is checked against all light sources, and the actual color is found with the lambert light model. If a object totally obstructs a shadow ray, that ray does not contribute to the diffuse lighting.

getColorBulb()

RGBA getColorBulb	(	double	lambert,
		RGB	objColor,
		RGB	lightColor,
		double	t
	)

Get the Color of Bulb (scene light)

Parameters

lambert	The lambert constant.
objColor	The color of the object.
lightColor	The color of the light.

Returns

RGB The linear RGB color, after blending.

This function applies the lambert constant to the light color and get the correct color by blending the colors of the light and the object, and applys light intensity falloff. Also takes care of exposure.`

getColorSun()

RGBA getColorSun	(	double	lambert,
		RGB	objColor,
		RGB	lightColor
	)

Get the Color of Sun (directional light)

Parameters

lambert	The lambert constant.
objColor	The color of the object.
lightColor	The color of the light.

Returns

RGB The linear RGB color, after blending.

This function applies the lambert constant to the light color and get the correct color by blending the colors of the light and the object. Also takes care of exposure.

globalIllumination()

RGBA globalIllumination	(	const ObjectInfo &	obj,
		int	gi_bounce
	)

Get the global illumination light color.

Parameters

obj	The objectInfo instance with the intersection information.
gi_bounce	Remaining bounces for global illumination rays.

Returns

RGBA The RGBA linear color at the location.

A gi ray is created by selecting a new ray in the sphere at the intersection point. This gi ray, after intersection, can create more gi rays based on the remaining gi bounce.

Deprecated:

This version of global illumination is too slow and does not work that well. Will be replaced by something better later.

hitMiss()

ObjectInfo hitMiss

(

)

Does nothing.

Returns

ObjectInfo A default no-hit objectInfo.

hitNearest()

ObjectInfo hitNearest

(

Ray &

ray

)

Gets the nearest object in the path of the ray.

Parameters

ray	The ray to trace.

Returns

ObjectInfo All the related info for the object, if any is hit.

reflectionLight()

RGBA reflectionLight	(	const Ray &	ray,
		const ObjectInfo &	obj
	)

Get the reflection light color.

Parameters

ray	The ray which caused the reflection.
obj	The objectInfo instance with the intersection information.

Returns

RGBA The RGBA linear color at the location.

The reflection ray is calculated and checked against all objects in the scene. If the reflection ray did hit an object, a full light calculation is performed to achieve the reflection lighting effect.

refractionLight()

RGBA refractionLight	(	const Ray &	ray,
		const ObjectInfo &	obj
	)

Get the refraction light color.

Parameters

ray	The ray which caused the refraction.
obj	The objectInfo instance with the intersection information.

Returns

RGBA The RGBA linear color at the location.

The refraction discriminant (k) is calculated and if k < 0, total internal refraction occur, which is treated as reflection. If not, the refraction ray is calculated, and checked against all objects again(this currently only works for spheres and could be optimized). When the ray hits the object again, the final refraction ray is calculated using the inverse of the ior ratio during ray entrance. After the ray exits, full light calculation is performed.

Note

Currently this function only handles air-object intersection. It also assumes that total internal refraction will not happen inside the object itself, and the sphere-intersection could be optimized when the ray is inside the object.

render()

void render

(

Image &

img

)

The render function that loops over the screen of pixels.

Parameters

img	The image to render on.

Loops over all pixels in the canvas and shoots a primary ray at that pixel. Shoot multiple rays if anti-alising is on.

shootPrimaryRay()

RGBA shootPrimaryRay	(	double	x,
		double	y
	)

Shoots a primary ray into the scene, at pixel location (x,y).

Parameters

x	x coordinate of the pixel.
y	y coordinate of the pixel.

Returns

RGBA the final pixel color value, in linear RGB color space.

This function shoots one primary ray for the pixel (x,y). It will calculate the color for the pixel with the nearest object the primary ray hit, and the final color will be the blend of diffuse, reflect, refract and global illumination color. The latter three could create more rays that will bounce in the scene.