用C++写一个三维空间拖拽器

好的，我可以为您提供一个基本的三维空间拖拽器的C代码。请注意，此代码仅用于演示和教育目的，并未在实际应用中进行严格测试和验证。代码如下：

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#define PI 3.1415926535

// 定义三维向量结构体
typedef struct {
    float x;
    float y;
    float z;
} Vector3;

// 定义四元数结构体
typedef struct {
    float w;
    Vector3 v;
} Quaternion;

// 将角度转换为弧度
float ToRadians(float degrees) {
    return degrees * PI / 180.0f;
}

// 计算向量的模长
float Vector3Magnitude(Vector3 v) {
    return sqrtf(v.x * v.x + v.y * v.y + v.z * v.z);
}

// 将向量归一化
Vector3 Vector3Normalize(Vector3 v) {
    float magnitude = Vector3Magnitude(v);
    if (magnitude > 0) {
        v.x /= magnitude;
        v.y /= magnitude;
        v.z /= magnitude;
    }
    return v;
}

// 计算向量点积
float Vector3Dot(Vector3 v1, Vector3 v2) {
    return v1.x * v2.x + v1.y * v2.y + v1.z * v2.z;
}

// 计算向量叉积
Vector3 Vector3Cross(Vector3 v1, Vector3 v2) {
    Vector3 v;
    v.x = v1.y * v2.z - v1.z * v2.y;
    v.y = v1.z * v2.x - v1.x * v2.z;
    v.z = v1.x * v2.y - v1.y * v2.x;
    return v;
}

// 计算四元数的模长
float QuaternionMagnitude(Quaternion q) {
    return sqrtf(q.w * q.w + q.v.x * q.v.x + q.v.y * q.v.y + q.v.z * q.v.z);
}

// 将四元数归一化
Quaternion QuaternionNormalize(Quaternion q) {
    float magnitude = QuaternionMagnitude(q);
    if (magnitude > 0) {
        q.w /= magnitude;
        q.v.x /= magnitude;
        q.v.y /= magnitude;
        q.v.z /= magnitude;
    }
    return q;
}

// 计算四元数共轭
Quaternion QuaternionConjugate(Quaternion q) {
    Quaternion result;
    result.w = q.w;
    result.v.x = -q.v.x;
    result.v.y = -q.v.y;
    result.v.z = -q.v.z;
    return result;
}

// 计算四元数乘法
Quaternion QuaternionMultiply(Quaternion q1, Quaternion q2) {
    Quaternion result;
    result.w = q1.w * q2.w - Vector3Dot(q1.v, q2.v);
    result.v = Vector3Add(Vector3Add(Vector3Cross(q1.v, q2.v), Vector3Multiply(q2.v, q1.w)), Vector3Multiply(q1.v, q2.w));
    return result;
}

// 根据旋转轴和旋转角度计算四元数
Quaternion QuaternionFromAxisAngle(Vector3 axis, float angle) {
    Quaternion result;
    angle = ToRadians(angle);
    result.w = cosf(angle / 2.0f);
    result.v = Vector3Multiply(axis, sinf(angle / 2.0f));
    return result;
}

// 根据欧拉角计算四元数
Quaternion QuaternionFromEulerAngles(float pitch, float yaw, float roll) {
    pitch = ToRadians(pitch);
    yaw = ToRadians(yaw);
    roll = ToRadians(roll);

    float cy = cosf(yaw / 2.0f);
    float sy = sinf(yaw / 2.0f);
    float cr = cosf(roll / 2.0f);
    float sr = sinf(roll / 2.0f);
    float cp = cosf(pitch / 2.0f);
    float sp = sinf(pitch / 2.0f);

    Quaternion result;
    result.w = cy * cr * cp + sy * sr * sp;
    result.v.x = cy * sr * cp - sy * cr * sp;
    result.v.y = cy * cr * sp + sy * sr * cp;
    result.v.z = sy * cr * cp - cy * sr * sp;

    return result;
}

// 根据四元数计算旋转矩阵
void Matrix4FromQuaternion(float* matrix, Quaternion q) {
    matrix[0] = 1 - 2 * q.v.y * q.v.y - 2 * q.v.z * q.v.z;
    matrix[1] = 2 * q.v.x * q.v.y - 2 * q.w * q.v.z;
    matrix[2] = 2 * q.v.x * q.v.z + 2 * q.w * q.v.y;
    matrix[3] = 0;

    matrix[4] = 2 * q.v.x * q.v.y + 2 * q.w * q.v.z;
    matrix[5] = 1 - 2 * q.v.x * q.v.x - 2 * q.v.z * q.v.z;
    matrix[6] = 2 * q.v.y * q.v.z - 2 * q.w * q.v.x;
    matrix[7] = 0;

    matrix[8] = 2 * q.v.x * q.v.z - 2 * q.w * q.v.y;
    matrix[9] = 2 * q.v.y * q.v.z + 2 * q.w * q.v.x;
    matrix[10] = 1 - 2 * q.v.x * q.v.x - 2 * q.v.y * q.v.y;
    matrix[11] = 0;

    matrix[12] = 0;
    matrix[13] = 0;
    matrix[14] = 0;
    matrix[15] = 1;
}

// 根据旋转矩阵计算四元数
Quaternion QuaternionFromMatrix4(float* matrix) {
    float trace = matrix[0] + matrix[5] + matrix[10];
    float w, x, y, z;

    if (trace > 0) {
        float s = 0.5f / sqrtf(trace + 1.0f);
        w = 0.25f / s;
        x = (matrix[9] - matrix[6]) * s;
        y = (matrix[2] - matrix[8]) * s;
        z = (matrix[4] - matrix[1]) * s;
    } else {
        if (matrix[0] > matrix[5] && matrix[0] > matrix[10]) {
            float s = 2.0f * sqrtf(1.0f + matrix[0] - matrix[5] - matrix[10]);
            w = (matrix[9] - matrix[6]) / s;
            x = 0.25f * s;
            y = (matrix[1] + matrix[4]) / s;
            z = (matrix[2] + matrix[8]) / s;
        } else if (matrix[5] > matrix[10]) {
            float s = 2.0f * sqrtf(1.0f + matrix[5] - matrix[0] - matrix[10]);
            w = (matrix[2] - matrix[8]) / s;
            x = (matrix[1] + matrix[4]) / s;
            y = 0.25f * s;
            z = (matrix[6] + matrix[9]) / s;
        } else {
            float s = 2.0f * sqrtf(1.0f + matrix[10] - matrix[0] - matrix[5]);
            w = (matrix[4] - matrix[1]) / s;
            x = (matrix[2] + matrix[8]) / s;
            y = (matrix[6] + matrix[9]) / s;
            z = 0.25f * s;
        }
    }

    Quaternion result;
    result.w = w;
    result.v.x = x;
    result.v.y = y;
    result.v.z = z;

    return result;
}

// 根据鼠标事件计算旋转四元数
Quaternion CalculateRotationQuaternion(int x, int y, int lastX, int lastY, int width, int height) {
    float dx = (float)(x - lastX) / (float)width;
    float dy = (float)(y - lastY) / (float)height;

    float angle = sqrtf(dx * dx + dy * dy) * 180.0f;
    Vector3 axis = Vector3Normalize(Vector3Cross(Vector3Normalize(Vector3Make(dx, dy, 0)), Vector3Make(0, 0, 1)));

    return QuaternionMultiply(QuaternionFromAxisAngle(axis, angle), g_rotation);
}

// 根据鼠标事件计算平移向量
Vector3 CalculateTranslationVector(int x, int y, int lastX, int lastY, int width, int height) {
    float dx = (float)(x - lastX) / (float)width;
    float dy = (float)(y - lastY) / (float)height;

    float distance = sqrtf(dx * dx + dy * dy) * 10.0f;
    Vector3 direction = Vector3Normalize(Vector3Make(dx, dy, 0));

    return Vector3Add(g_translation, Vector3Multiply(direction, distance));
}

// 主循环
void MainLoop() {
    while (1) {
        // 处理鼠标事件
        // ...

        // 计算旋转四元数
        Quaternion rotation = CalculateRotationQuaternion(x, y, lastX, lastY, width, height);

        // 计算平移向量
        Vector3 translation = CalculateTranslationVector(x, y, lastX, lastY, width, height);

        // 更新旋转和平移状态
        g_rotation = QuaternionMultiply(rotation, g_rotation);
        g_translation = translation;

        // 计算模型视图矩阵
        float modelViewMatrix[16];
        Matrix4FromQuaternion(modelViewMatrix, QuaternionConjugate(g_rotation));
        modelViewMatrix[12] = -g_translation.x;
        modelViewMatrix[13] = -g_translation.y;
        modelViewMatrix[14] = -g_translation.z;

        // 渲染场景
        // ...
    }
}

int main() {
    // 初始化旋转和平移状态
    g_rotation = QuaternionFromEulerAngles(0, 0, 0);
    g_translation = Vector3Make(0, 0, 0);

    // 进入主循环
    MainLoop();

    return 0;
}

这个代码实现了一个简单的三维空间拖拽器，可以通过鼠标事件来控制模型的旋转和平移。请注意，这个代码只是一个示例，实际应用中可能需要做更多的优化和改进，以满足特定的需求。