如何更新Raylib中的屏幕/重新绘制屏幕？

Question

作为学习C++的一种方法，我想使用图形框架进行双摆模拟，所以我选择了Raylib，因为它是我唯一需要的框架。到目前为止，我已经能够画出一个双摆，并且我能够修改角度，这样每当θ被修改时，它就会改变摆的位置。但是，每当我试图在主within循环中更新theta1或theta2时，我就无法对其进行动画化。在我真正实现一些物理之前，我需要知道我将能够根据它的不同角度来动画这个钟摆。只有当我第一次设定角度时，它才会改变。我不能重新设置其他地方的角度，只是刚开始，我是新的C++.

pendulum.h

#ifndef DOUBLE_PENDULUM_SIM_PENDULUM_H
#define DOUBLE_PENDULUM_SIM_PENDULUM_H


class pendulum {
public:

    float pLength{};
    float pMass{};
    float x{};
    float y{};
    float pAngle{};

public:

    [[nodiscard]] float getX() const ;
    [[nodiscard]] float getY() const ;

    [[nodiscard]] float getAngle() const ;

    void setX(float length, float angle);
    void setY(float length, float angle);

    void setLength(float length);
    void setMass(float mass);
    void setAngle(float angle);

    pendulum();

    pendulum(float length, float mass, float angle) : pLength(length), pMass(mass), pAngle(angle) {}

    ~pendulum();


};

#endif //DOUBLE_PENDULUM_SIM_PENDULUM_H

pendulum.cpp

#include "includes/pendulum.h"
#include <cmath>
#include <iostream>
#include <raylib.h>

void pendulum::setX(float length, float angle) {
    x = length * sin(angle);
}

void pendulum::setY(float length, float angle) {
    y = length * cos(angle);
}

float pendulum::getX() const {
    return x;
}

float pendulum::getY() const {
    return y;
}

void pendulum::setLength(float length) {
    pLength = length;
}

void pendulum::setMass(float mass) {
    pMass = mass;
}

float pendulum::getAngle() const {
    return pAngle;
}

pendulum::~pendulum() {
    std::cout << "Pendulum destroyed" << std::endl;
}

void pendulum::setAngle(float angle) {
    pAngle = angle * DEG2RAD;
}

//Default constructor
pendulum::pendulum() = default;

main.cpp

#include <iostream>
#include "raylib.h"
#include "includes/pendulum.h"
#include <rlgl.h>
#include <cmath>

void _testPendulum();

pendulum pen1;
pendulum pen2;

int main() {

    float theta1 = 0.0f;
    float theta2 = 0.0f;

    pen1.setMass(20.0f);
    pen1.setLength(150.0f);
    pen1.setAngle(theta1); //Can only set this once and cant anywhere else, why?
    pen1.setX(pen1.pLength,pen1.getAngle());
    pen1.setY(pen1.pLength, pen1.getAngle());

    std::cout << "X coord: " << pen1.getX() << " Y coord: " << pen1.getY() << std::endl;

    pen2.setMass(50.0f);
    pen2.setLength(150.0f);
    pen2.setAngle(theta2); //Can only set this once and cant anywhere else, why?
    pen2.setX( pen2.pLength,pen2.getAngle());
    pen2.setY( pen2.pLength,pen2.getAngle());
    pen2.x = pen1.getX() + pen2.getX();
    pen2.y = pen1.getY() + pen2.getY();

    std::cout << "X coord: " << pen2.getX() << " Y coord: " << pen2.getY() << std::endl;

    Vector2 origin{0,0};

    double screenWidth = 800;
    double screenHeight = 800;

    float px1 = pen1.getX();
    float py1 = pen1.getY();

    float px2 = pen2.getX();
    float py2 = pen2.getY();

    Vector2 rod1{px1,py1};
    Vector2 rod2 {px2, py2};

    /**--------------------------TEST VARIABLES--------------------------*/
    //Pendulum 1 & 2 properties:
    float l1 = 150.0f; //Length 1
    float l2 = 150.0f; //Length 2

    float m1 = 20.0f;
    float m2 = 20.0f;

    static float angle1 = 0.0f * DEG2RAD;
    static float angle2 = 0.0f * DEG2RAD;

    //First pendulum x & y
    float x1 = l1 * sin(theta1);
    float y1 = l1 * cos(theta1);

    //Second pendulum x & y
    float x2 = x1 + (l2 * sin(theta2));
    float y2 = y1 + (l2 * cos(theta2));
    /**--------------------------TEST VARIABLES--------------------------*/

    InitWindow((int) screenWidth, (int) screenHeight, "Double-Pendulum-Sim");

    int state = 0;
    int frameCounter = 0;

    SetTargetFPS(60);


    while (!WindowShouldClose()) {

        /**------------------Update------------------*/
        if(state == 0) {

            frameCounter++;
            theta1 = (float) frameCounter;
            pen1.setAngle(theta1);

            if(frameCounter >= 500) {
                frameCounter = 0;
                state = 1;
            }

        } else if(state == 1) {

            frameCounter++;
            theta2 = (float) frameCounter;
            pen2.setAngle(theta2);

            if(frameCounter >= 600) {
                frameCounter = 0;
                state = 2;
            }
        }

    /**---------------------------------Draw-Pendulums---------------------------------- */
        BeginDrawing();

            ClearBackground(BLACK);

            DrawFPS(-350, -200);

            rlTranslatef(400,250,0);

            DrawLineEx(origin, rod1, 5.0f, RAYWHITE);
            DrawCircle(px1,py1,pen1.pMass,RAYWHITE);

            DrawLineEx(rod1, rod2, 5.0f, RAYWHITE);
            DrawCircle(px2,py2,pen2.pMass,RAYWHITE);

            std::cout << "Pendulum 1 X & Y: " << pen1.getX() << " " << pen1.getY() << std::endl;
            std::cout << "Pendulum 2 X & Y: " << pen2.getX() << " " << pen2.getY() << std::endl;

        EndDrawing();
    }


    CloseWindow();


    return 0;
}

//Test function
void _testPendulum() {

    try {
        pen1.setMass(20.0f);
        pen1.setLength(150.0f);
        pen1.setAngle(0.0f);
        pen1.setX(pen1.pLength,pen1.getAngle());
        pen1.setY(pen1.pLength, pen1.getAngle());

        std::cout << "X coord: " << pen1.getX() << " Y coord: " << pen1.getY() << std::endl;

        pen2.setMass(50.0f);
        pen2.setLength(150.0f);
        pen2.setAngle(0.0f);
        pen2.setX( pen2.pLength,pen2.getAngle());
        pen2.setY( pen2.pLength,pen2.getAngle());
        pen2.x = pen1.getX() + pen2.getX();
        pen2.y = pen1.getY() + pen2.getY();

        std::cout << "X coord: " << pen2.getX() << " Y coord: " << pen2.getY() << std::endl;

    } catch (const std::exception & e) {
        std::cout << e.what();
    }

}

Answer 1

在看完之后，我注意到要画出实际的形状，我需要使用变量px1, px2, py1, py2的摆x和y分量。因此，我需要更新这些变量，同时增加角度。这不是完整的钟摆模拟器，这只是使它在增加角度时移动的修正，完成后将发布Github链接。而且，唯一修改的文件是main.cpp，因此它是唯一将被共享的文件。

main.cpp：

#include <iostream>
#include "raylib.h"
#include "includes/pendulum.h"
#include <rlgl.h>
#include <cmath>

void _testPendulum();

pendulum pen1;
pendulum pen2;


int main() {


    //Prompt to make the initial values themselves
    float uLength1, uLength2, uMass1, uMass2, uAngle1, uAngle2;

    try {

        std::cout << "Please choose the length of each pendulum, starting with Pendulum 1, then Pendulum 2. Each value provided can be up to 7 decimal digits" << "\n";
        std::cin >> uLength1 >> uLength2;
        std::cout << "Please choose the mass of each pendulum, starting with Pendulum 1, then Pendulum 2. Each value provided can be up to 7 decimal digits" << "\n";
        std::cin >> uMass1 >> uMass2;
        std::cout << "Please choose the starting angle of each pendulum, starting with Pendulum 1, then Pendulum 2. Each value provided can be up to 7 decimal digits" << "\n";
        std::cin >> uAngle1 >> uAngle2;

    } catch (const std::exception & e) {
        std::cout << e.what();
    }



    pen1.setMass(uMass1);
    pen1.setLength(uLength1);
    pen1.setAngle(uAngle1); //Can only set this once and cant anywhere else, why?
    pen1.setX(pen1.pLength,pen1.getAngle());
    pen1.setY(pen1.pLength, pen1.getAngle());

    std::cout << "X coord: " << pen1.getX() << " Y coord: " << pen1.getY() << std::endl;

    pen2.setMass(uMass2);
    pen2.setLength(uLength2);
    pen2.setAngle(uAngle2); //Can only set this once and cant anywhere else, why?
    pen2.setX( pen2.pLength,pen2.getAngle());
    pen2.setY( pen2.pLength,pen2.getAngle());
    pen2.x = pen1.getX() + pen2.getX();
    pen2.y = pen1.getY() + pen2.getY();

    std::cout << "X coord: " << pen2.getX() << " Y coord: " << pen2.getY() << std::endl;

    Vector2 origin{0,0};

    double screenWidth = 800;
    double screenHeight = 800;

    InitWindow((int) screenWidth, (int) screenHeight, "Double-Pendulum-Sim");

    int frameCounter = 0;

    SetTargetFPS(60);

    float px1 = pen1.getX();
    float py1 = pen1.getY();

    float px2 = pen2.getX();
    float py2 = pen2.getY();

    while (!WindowShouldClose()) {


        Vector2 rod1{px1,py1};
        Vector2 rod2 {px2, py2};

        /**------------------Update------------------*/

            frameCounter++;
            uAngle1 = (float) frameCounter;
            pen1.setAngle(uAngle1); //Can only set this once and cant anywhere else, why?
            pen1.setX(pen1.pLength,pen1.getAngle());
            pen1.setY(pen1.pLength, pen1.getAngle());

            px1 = pen1.getX();
            py1 = pen1.getY();

            uAngle2 += 5.0f;
            pen2.setAngle(uAngle2); //Can only set this once and cant anywhere else, why?
            pen2.setX( pen2.pLength,pen2.getAngle());
            pen2.setY( pen2.pLength,pen2.getAngle());
            pen2.x = pen1.getX() + pen2.getX();
            pen2.y = pen1.getY() + pen2.getY();

            px2 = pen2.getX();
            py2 = pen2.getY();


    /**---------------------------------Draw-Pendulums---------------------------------- */
        BeginDrawing();

            ClearBackground(BLACK);

            DrawFPS(-350, -200);

            rlTranslatef(400,250,0);

            DrawLineEx(origin, rod1, 5.0f, RAYWHITE);
            DrawCircle(px1,py1,pen1.pMass,RAYWHITE);

            DrawLineEx(rod1, rod2, 5.0f, RAYWHITE);
            DrawCircle(px2,py2,pen2.pMass,RAYWHITE);

            std::cout << "Pendulum 1 X & Y: " << pen1.getX() << " " << pen1.getY() << std::endl;
            std::cout << "Pendulum 2 X & Y: " << pen2.getX() << " " << pen2.getY() << std::endl;

        EndDrawing();
    }

    CloseWindow();

    return 0;
}

//Test function
void _testPendulum() {

    try {
        pen1.setMass(20.0f);
        pen1.setLength(150.0f);
        pen1.setAngle(0.0f);
        pen1.setX(pen1.pLength,pen1.getAngle());
        pen1.setY(pen1.pLength, pen1.getAngle());

        std::cout << "X coord: " << pen1.getX() << " Y coord: " << pen1.getY() << std::endl;

        pen2.setMass(50.0f);
        pen2.setLength(150.0f);
        pen2.setAngle(0.0f);
        pen2.setX( pen2.pLength,pen2.getAngle());
        pen2.setY( pen2.pLength,pen2.getAngle());
        pen2.x = pen1.getX() + pen2.getX();
        pen2.y = pen1.getY() + pen2.getY();


        std::cout << "X coord: " << pen2.getX() << " Y coord: " << pen2.getY() << std::endl;

    } catch (const std::exception & e) {
        std::cout << e.what();
    }

}