Question

所以我有一个物体（球体），我想将球体的y轴与用于绘制其中点的矢量对齐。

现在，所有创建的对象都有轴＆＃39;如下所示设置，因此在世界空间中创建的所有内容都具有轴方向，如下图所示。但是我希望球体的轴在局部坐标中的y轴在它们的父对象（它们所围绕的球体）的方向上，但是我不确定我可以为每个对象做什么毯子转换为了这个转型发生。

下图是物体的理想方向。

我需要这个方向，所以孩子的球体而不是像他们在下面的两张图片中那样向上指向，根据方向向外突出。因此，如果我要在底部生成一个球体，而不是在其x轴顶部生成子球体，然后将其与大中心球体合并，则它们向外指向远离大中心球体

下面是我生成球体的代码（我在这段代码中产生了比图9更多的球体，但是减少了图片中存在的球体数量，以便澄清并且不会使图像混乱）

bool static CreateSphereLevels(Sphere *parent, float childRadiusRatio, int levels,
            Material** materials)

{
    if (levels == 1) {
        for (int i = 0; i < 6; i++) {
            Sphere * s = new Sphere(childRadiusRatio, materials[i % 6]);
            parent->AddChild(s);
            float rm = parent->GetRadius() + s->GetRadius();
            if (i == 0)
                s->SetPosition(vec3(0.0f, rm, 0.0f));
            if (i >= 1 && i < 6)
                s->SetPosition(vec3(RotationY(60 * i) * vec4(0.0f, rm, 0.0f, 0.0f)));
            if (i == 1 || i == 3 || i == 5) {
                Sphere * sn = new Sphere(childRadiusRatio, materials[i]);
                parent->AddChild(sn);
                sn->SetPosition(vec3(RotationY(60 * i) * RotationZ(60) * vec4(0.0f, rm, 0.0f, 0.0f)));
            }
        }
        return true;
    }
    else {
        for (int i = 0; i < 6; i++) {
            Sphere * s = new Sphere(childRadiusRatio, materials[i % 6]);
            parent->AddChild(s);
            int newLevels = levels - 1;
            CreateSphereLevels(s, (childRadiusRatio / 3), newLevels, materials);
            float rm = parent->GetRadius() + s->GetRadius();
            if (i == 0)
                s->SetPosition(vec3(0.0f, rm, 0.0f));
            if (i >= 1 && i < 6)
                s->SetPosition(vec3(RotationY(60 * i) * vec4(0.0f, rm, 0.0f, 0.0f)));
            if (i == 1 || i == 3 || i == 5) {
                Sphere * sn = new Sphere(childRadiusRatio, materials[i]);
                parent->AddChild(sn);
                CreateSphereLevels(sn, (childRadiusRatio / 3), newLevels, materials);
                sn->SetPosition(vec3(RotationY(60 * i) * RotationZ(60) * vec4(0.0f, rm, 0.0f, 0.0f)));
            }
        }
    }
    return true;
}

下面是可以对我的对象执行的可能转换

#ifndef RAYTRACER_SCENES_SCENEOBJECT_H
#define RAYTRACER_SCENES_SCENEOBJECT_H

#include <Raytracer/Scenes/SceneObjectType.h>

#include <vector>

namespace Raytracer
{
    namespace Scenes
    {
        class SceneObject
        {
        private:

            /**
             * The transformation matrix to transform a point from world coordinates to local
             * coordinates.
             */
            glm::mat4x4 globalTransformation;

            glm::mat4x4 transformation;

            glm::mat4x4 globalToLocal;

            /**
             * Updates the global transformation based on the current transformation. This
             * includes child objects.
             */
            void UpdateTransformations();

            std::vector<SceneObject *> children;
            SceneObject * parent;

        public:

            /**
             * Constructs a new SceneObject.
             */
            SceneObject();

            /**
             * Destructs a SceneObject and deletes all child objects.
             */
            virtual ~SceneObject();

            /**
             * Adds a new child to this object.
             *
             * @param child The new child object. This object becomes child's parent object. This
             *   object takes ownership of child.
             * @return true if the child was added successfully, false otherwise.
             */
            bool AddChild(SceneObject *child);

            /**
             * Retrieves a list of all children of this object.
             *
             * @return A list of all children of this object
             */
            const std::vector<SceneObject *> &GetChildren() const;

            /**
            * Retrieves the position of this object in world space, i.e. the translation component
            * of the global transformation matrix.
            *
            * @return The global position of this object
            */
            const glm::vec3 GetGlobalPosition() const;

            /**
            * Retrieves a matrix that can be used to transform coordinates from world space to
            * object space. This is the inverse of the global transformation matrix.
            *
            * @return The inverse of the global transformation matrix
            */
            const glm::mat4x4 &GetGlobalToLocal() const;

            /**
             * Retrieves the global transformation matrix. The global transformation matrix is used
             * to transform coordinates from object space to world space.
             *
             * @return The global transformation matrix
             */
            const glm::mat4x4 &GetGlobalTransformation() const;

            /**
             * Retrieves the parent object of this object.
             *
             * @param The parent object of this object or NULL if this object has no parent
             */
            SceneObject *GetParent() const;

            /**
             * Retrieves the position of this object, i.e. the translation component of the
             * transformation matrix.
             *
             * @return The position of the object
             */
            const glm::vec3 GetPosition() const;

            /**
             * Retrieves the transformation matrix. The transformation matrix is used to transform
             * coordinates from object space to the object space of the parent object (or world
             * space if this object has no parent).
             *
             * @return The transformation matrix
             */
            const glm::mat4x4 &GetTransformation() const;

            /**
             * Checks whether this instance is of the given type.
             *
             * @param type The type to check against
             * @return true if this object is of type type, false otherwise
             */
            virtual bool IsInstanceOf(SceneObjectType type) const = 0;

            /**
            * Sets the global transformation matrix. The global transformation matrix is used
            * to transform coordinates from object space to world space.
            *
            * @param transformation The new global transformation matrix
            */
            void SetGlobalTransformation(const glm::mat4x4 &transformation);

            /**
             * Sets the position of this object, i.e. the translation component of the
             * transformation matrix.
             *
             * @param position The new position
             */
            void SetPosition(const glm::vec3 &position);

            /**
             * Sets the transformation matrix. The transformation matrix is used to transform
             * coordinates from object space to the object space of the parent object (or world
             * space if this object has no parent).
             *
             * @param transformation The new transformation matrix
             */
            void SetTransformation(const glm::mat4x4 &transformation);

            void ChildRemove(SceneObject * child);
        };
    }
}

#endif // RAYTRACER_SCENES_SCENEOBJECT_H

Answer 1

换句话说，您想要一种方法将您的子球体指向父球体。

通过从父项中减去子项的位置（以获得指向父项中心的Y轴）来计算子项的新Y轴方向并对其进行标准化。通过将新的Y轴向量与现有的Z轴向量（在左手系统中）交叉来计算新的X轴，注意处理它们指向相同方向或彼此完全相反的情况（可能正规化以移除错误）。然后将这个新的X轴向量与新的Y轴向量交叉以获得新的Z轴向量。将其存储在孩子的方向矩阵中。

如何将对象的Y轴与从其父级的中心点终止的向量对齐

1 个答案: