Question

我一直在尝试使用光线追踪和phong来实现飞机。我还没能让它出现。

我目前有3个阴影效果的球体，但似乎无法使飞机起作用。任何人都可以发现为什么我的飞机没有显示以及为什么发生segFault的问题？（我解释了确切的行以及我如何避免在下面获得segFault，所以我觉得我已经找到了问题）

我希望这架飞机能够像地板一样可以看到阴影。我只包括相关的平面代码，并省略了球体的东西以便于阅读。如果有人要求，我可以加入。（Sphere stuff working：http://imgur.com/i936UID，squarePlane代码的行“tmin = t”已注释掉以显示此内容。）

SegFault发生在

上的implementPhong函数中

vec3 R = vec3 (0,0,0);
//normalize(reflect(-L, N));
//vec3 (0,0,0);

如果我使用注释掉的normalize函数而不是我的临时vec3(0,0,0)。

如果我移动

，它也将是segFault

squarePlane.normal = normalize(vec3(0,0.5,3)); // to (vec3(0,1,0))

//********** Global Variables *********
RgbImage * myImage;
vec3 nEye(0.0,0.0,-5.0);
vec3 lightSource1(-2.0,-1.5,0.0);
vec3 lightSource2(0.0,-2.0,0.0);
float tmin=100.0;


struct Ray
{
    vec3 pt;
    vec3 vecDir;
};

struct Prim
{
    vec3 origin;
    double radius;
    double underSquare;
    vec3 ambient;
    vec3 diffuse_albedo;
    vec3 specular_albedo;
    float specular_power;
    vec3 light_intensity;
    vec3 normal;
    vec3 pt1;
    vec3 pt2;
    vec3 pt3;
};


vec3 trace(Ray ray){
    Prim squarePlane;
    Prim pickSphere;
    tmin = 100;
    vec3 pixelColor(0,0,1);
    squarePlane.pt1 = vec3(-0.2,0.0,0.0);
    squarePlane.pt2 = vec3(0.2,0.0,0.0);
    squarePlane.pt3 = vec3(-0.2,0.1,0.0);
    squarePlane.ambient=vec3(0.329412, 0.223529, 0.027451);
    squarePlane.diffuse_albedo=vec3(0.780392, 0.568627, 0.113725);
    squarePlane.specular_albedo = vec3(0.992157,0.941176,0.807843);
    squarePlane.specular_power = 27.8974;
    squarePlane.light_intensity = vec3(1,1,1);
    squarePlane.normal = normalize(vec3(0,1,0));

    float D = 0;
    float denom = dot(squarePlane.normal, nVecDir);
    float numer = dot(squarePlane.normal, nEye) + D;
    vec3 hitTemp;
    vec3 hitPoint;
    if (denom!=0){
        float t= -(dot(squarePlane.normal, nEye) + D) / denom;
        if (t>=0){
            tmin=t;
        }
    }
    //pickSphere = squarePlane;

    pickSphere = checkForIntersection(nEye, nVecDir, spheres, false);  // last parameter is for print debugging

    if (tmin != 100){ //if tmin has changed, we found and intersection, send shadow ray
        vec3 hitTemp(nVecDir.x*tmin, nVecDir.y*tmin, nVecDir.z*tmin);
        vec3 hitPoint = (nEye + hitTemp);
        shadowRay.vecDir = (normalize(lightSource1 - (hitPoint)));

        tmin = 100;  // Set tmin for a new ray trace.
        checkForIntersection(hitPoint, shadowRay.vecDir, spheres, true);

        if (tmin != 100){ //if tmin does not equal 100, we found an intersection, this point is in shadow, return ambient.
            pixelColor = pickSphere.ambient;
            return pixelColor;
        }
        else {
            pickSphere.normal = hitPoint - pickSphere.origin;
            pixelColor = implementPhong(pickSphere,nEye,hitPoint);
            //pixelColor = vec3(0,1,0);
            return pixelColor;
        }
    }
    else{
        return pixelColor;
    }
}


vec3 implementPhong(Prim drawSphere, vec3 camera, vec3 hitPoint){ 
    vec3 L = drawSphere.light_intensity * normalize(lightSource1 - hitPoint);
    vec3 N = normalize(drawSphere.normal);
    vec3 V = normalize(camera - hitPoint);
    vec3 R = vec3 (0,0,0); //normalize(reflect(-L, N)); //vec3 (0,0,0);
    float zero = 0;

    vec3 diffuse = std::max<float>(dot(N, L), zero) * drawSphere.diffuse_albedo;

    vec3 specular = pow(std::max<float>(dot(R, V), zero), drawSphere.specular_power) * drawSphere.specular_albedo; 

    vec3 color = drawSphere.ambient + diffuse + specular;

    return color;
}

C ++使用光线跟踪创建一个方形楼层平面。段错误

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