如何在Raylib中跟踪带有像素的路径？

Question

我正在用Raylib制作一个双摆模拟器，在深入了解它的工作原理之前，我想完成它的图形创建。

到目前为止，我创建了一个窗口，制作了一个双摆，可以任意旋转摆，但在研究物理之前，我最不需要做的事情是跟踪它的路径，我使用RenderTexture2D变量使用纹理来实现它。

然而，当这样做时，它确实跟踪路径，但只跟踪整个窗口的1/4，我不知道为什么。

它很可能与rltranslatef有关，但我不知道如何修复它。我有一个pendulum.h & .cpp文件，但它们与为此绘制图形无关。任何帮助都是非常感谢的。

摆：

#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 << "\nPendulum destroyed" << std::endl;
}

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

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

绘制主要图形的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" << "length MUST BE greater than 50 and less than 200" << "\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" << "mass MUST BE greater than 20 and less than 100" << "\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();
    }

    //Pendulum 1 settings

    pen1.setMass(uMass1);
    pen1.setLength(uLength1);
    pen1.setAngle(uAngle1);
    pen1.setX(pen1.pLength,pen1.getAngle());
    pen1.setY(pen1.pLength, pen1.getAngle());

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

    //Pendulum 2 settings

    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};

    const double screenWidth = 1440;
    const double screenHeight = 1080;


    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();

    RenderTexture2D target = LoadRenderTexture((int) screenWidth, (int) screenHeight);

    BeginTextureMode(target);
    ClearBackground(RAYWHITE);
    EndTextureMode();

    while (!WindowShouldClose()) {


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

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

            frameCounter++;
            uAngle1 += 1.0f;
            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 -= 1.0f;
            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();

            std::cout << frameCounter << std::endl;


    /**---------------------------------Draw-Pendulums & Path---------------------------------- */
    //TODO: Get pathing to work

    BeginDrawing();


            BeginTextureMode(target);
            DrawPixelV(rod2, RED);
            EndTextureMode();

            rlTranslatef((float) screenWidth/2,(float) screenHeight/4,0);

            DrawTextureRec(target.texture, (Rectangle){0,0, (float) target.texture.width, (float) -target.texture.height}, (Vector2){0,0}, WHITE);

            ClearBackground(RAYWHITE);

            DrawFPS(-350, -200);


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

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


            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

您的问题来自于DrawPixelV(rod2, RED);，它无法写出位置为负值的位置(尝试不使用rlTranslatef来查看这个想法)。

解决方案：

• 不使用以屏幕中心为中心的origin、px1、py1、px2和py2 (不是0，0)。

在main.cpp中，我更改了这些行，问题就消失了。

    Vector2 origin{700,200}; //  was origin{0,0};
...

    float px1 = pen1.getX() + 700; // +700 was not here
    float py1 = pen1.getY() + 200; // +200 was not here
    float px2 = pen2.getX() + 700;
    float py2 = pen2.getY() + 200;

...
    px1 = pen1.getX() + 700;
    py1 = pen1.getY() + 200;
...
    px2 = pen2.getX() + 700;
    py2 = pen2.getY() + 200;