I have something I don’t understand during the rotation of a 3D object.
The idea is that I want to rotate my object around the X and Y axes. Initially, at the initial position of the object, I can rotate it around X and around Y normally. As soon as I rotate my object 90 degrees around X, I can no longer rotate it around Y (it rotates around Z instead)! I tried the same thing by first rotating it 90 degrees around Y, then I rotate it around X and I see that it rotates around x !

Is this a matter of relative axis? But if that’s the case, it should be the same in the second case, right?

const char* vertexShaderSource = R"(
    #version 330 core
    layout (location = 0) in vec3 aPos;
    layout (location = 1) in vec3 aNormal;
    layout (location = 2) in vec2 aTexCoord;

    out vec3 FragPos;
    out vec3 Normal;
    out vec2 TexCoord;

    uniform mat4 model;
    uniform mat4 view;
    uniform mat4 projection;

    void main()
    {
        FragPos = vec3(model * vec4(aPos, 1.0));
        Normal = mat3(transpose(inverse(model))) * aNormal;
        TexCoord = aTexCoord;
        gl_Position = projection * view * model * vec4(aPos, 1.0);
    }
)";

void OpenGlWidget::paintGL()
{ 
    glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glBindTexture(GL_TEXTURE_2D, mPushButton->texture);
    glBindVertexArray(mPushButton->vao);
    glm::mat4 model = glm::rotate(glm::mat4(1.0f), glm::radians(m_rotationAngleX), glm::vec3(1.0f, 0.0f, 0.0f));
    model = glm::rotate(model, glm::radians(m_rotationAngleY), glm::vec3(0.0f, 1.0f, 0.0f));
    glUniformMatrix4fv(glGetUniformLocation(m_shaderProgram, "model"), 1, GL_FALSE, glm::value_ptr(model));
    glDrawElements(GL_TRIANGLES, mPushButton->indices.size(), GL_UNSIGNED_INT, 0);
    glBindVertexArray(0);      
}

void OpenGlWidget::mouseMoveEvent(QMouseEvent* event)
{
    if (event->buttons() & Qt::LeftButton) {
        int deltaX = event->x() - m_lastMousePos.x();
        int deltaY = event->y() - m_lastMousePos.y();
        m_lastMousePos = event->pos();

        m_rotationAngleX += deltaY * 0.5f;
        m_rotationAngleY += deltaX * 0.5f;

        update();
    }
}