绕 Y 轴旋转 gluLookAt

Question

我正在尝试围绕 y 轴旋转查看器。我有一个名为tranform_eye() 的函数，它将在每次更新后计算eyex、eyey 和eyez 的下一个位置。

谁能帮我弄清楚如何计算eyex、eyey 和eyez 的值？

我的代码：

float eyex = 5;
float eyey = 5;
float eyez = 5;

void display() {

    transform_eye();

    glMatrixMode(GL_PROJECTION);     // To operate on model-view matrix
    glLoadIdentity();
    gluPerspective(40.0, 1.0, 1.0, 10000.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    gluLookAt(eyex, eyey, eyez,
              0.0, 0.0, 0.0,
              0.0, 1.0, 0.0);

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear color and depth buffers

    drawTriangles();

    glutSwapBuffers();  // Swap the front and back frame buffers (double buffering)
}

void transform(){
    /// calculate new eyex, y z.
}

Answer 1

从例如应用数学this answer 给我们：

void transform()
{
    float theta = 0.01; //angle in radians to rotate every frame
    float cosTheta = cos(theta);
    float sinTheta = sin(theta);
    float newX = cosTheta * eyeX + sinTheta * eyeZ;
    eyeZ = -sinTheta * eyeX + cosTheta * eyeZ;
    eyeX = newX;
}