Path Tracing - Generate Camera Rays with a Left Handed coordinate system - rendering

Question

Been having some issues implementing a camera for my renderer. As the question states,I would like to know the necessary steps to generate such a camera.With field of view and aspect ratio included.Its important that the Coordinate system be left handed such that -z pushes the camera away from the screen(as I understand it).I have tried looking online but most of the implementations are incomplete or have failed me.Any help is appreciated.Thank You.

Answer 1

I had trouble with this and took a long time to figure out. Here is the code for camera class.
#ifndef CAMERA_H_
#define CAMERA_H_
#include "common.h"
struct Camera {
Vec3fa position, direction;
float fovDist, aspectRatio;
double imgWidth, imgHeight;
Mat4 camMatrix;
Camera(Vec3fa pos, Vec3fa cRot, Vec3fa cDir, float cfov, int width, int height) {
position = pos;
aspectRatio = width / (float)height;
imgWidth = width;
imgHeight = height;
Vec3fa angle = Vec3fa(cRot.x, cRot.y, -cRot.z);
camMatrix.setRotationRadians(angle * M_PI / 180.0f);
direction = Vec3fa(0.0f, 0.0f, -1.0f);
camMatrix.rotateVect(direction);
fovDist = 2.0f * tan(M_PI * 0.5f * cfov / 180.0);
}
Vec3fa getRayDirection(float x, float y) {
Vec3fa delta = Vec3fa((x-0.5f) * fovDist * aspectRatio, (y-0.5f) * fovDist, 0.0f);
camMatrix.rotateVect(delta);
return (direction + delta);
}
};
#endif
Incase if you need the rotateVect() code in the Mat4 class
void Mat4::rotateVect(Vector3& vect) const
{
Vector3 tmp = vect;
vect.x = tmp.x * (*this)[0] + tmp.y * (*this)[4] + tmp.z * (*this)[8];
vect.y = tmp.x * (*this)[1] + tmp.y * (*this)[5] + tmp.z * (*this)[9];
vect.z = tmp.x * (*this)[2] + tmp.y * (*this)[6] + tmp.z * (*this)[10];
}
Here is our setRotationRadians code
void Mat4::setRotationRadians(Vector3 rotation)
{
const float cr = cos(rotation.x);
const float sr = sin(rotation.x);
const float cp = cos(rotation.y);
const float sp = sin(rotation.y);
const float cy = cos(rotation.z);
const float sy = sin(rotation.z);
(*this)[0] = (cp * cy);
(*this)[1] = (cp * sy);
(*this)[2] = (-sp);
const float srsp = sr * sp;
const float crsp = cr * sp;
(*this)[4] = (srsp * cy - cr * sy);
(*this)[5] = (srsp * sy + cr * cy);
(*this)[6] = (sr * cp);
(*this)[8] = (crsp * cy + sr * sy);
(*this)[9] = (crsp * sy - sr * cy);
(*this)[10] = (cr * cp);
}