Question

在为渲染器实现相机时遇到了一些问题。正如问题所述，我想知道生成这样一个摄像机的必要步骤。包括视野和纵横比。重要的是坐标系左手使得-z将摄像机推离屏幕（如我明白了。）我试过在网上看，但大多数实施都不完整或者让我失望。感谢任何帮助。谢谢。

Answer 1

我遇到了麻烦，花了很长时间才弄明白。这是相机类的代码。

#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

如果您需要Mat4类中的rotateVect（）代码

，请注意

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];
}

这是我们的setRotationRadians代码

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);
}

路径跟踪 - 使用左手坐标系生成摄像机光线

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