如何在 Raylib 中制作具有厚度的 3D 三角形

Posted 2023-02-17

【中文标题】如何在 Raylib 中制作具有厚度的 3D 三角形

【英文标题】：How to make 3D triangle with thickness in Raylib

【发布时间】：2021-04-09 14:48:19

【问题描述】：

我可以在 Raylib 中制作一个 3D 三角形，但现在我希望那个三角形有厚度。

Raylib 如何做到这一点？

这是 C# 中的代码，它只显示一个没有厚度的三角形：

using System;
using Raylib_cs;
using System.Numerics;

namespace Triangle


    class Program
    

        static void Main(string[] args)
        



            Raylib.InitWindow(800, 480, "Hello World");
            Camera3D camera;
            camera.position = new Vector3(10.0f, 10.0f, 10.0f); // Camera3D position
            camera.target = new Vector3(0.0f, 0.0f, 0.0f);      // Camera3D looking at point
            camera.up = new Vector3(0.0f, 1.0f, 0.0f);          // Camera3D up vector (rotation towards target)
            camera.fovy = 120.0f;                                // Camera3D field-of-view Y
            camera.type = CameraType.CAMERA_PERSPECTIVE;        // Camera3D mode type



            Vector3 point1 = new Vector3(0.0f, 0.0f, 0.0f);
            Vector3 point2 = new Vector3(10.0f, 0.0f, 0.0f);
            Vector3 point3 = new Vector3(10.0f, 10.0f, 0.0f);

            Raylib.SetCameraMode(camera, CameraMode.CAMERA_FREE); // Set a free camera mode
            Raylib.SetTargetFPS(60);

            Rlgl.rlDisableBackfaceCulling();
            while (!Raylib.WindowShouldClose())
            
                Raylib.UpdateCamera(ref camera);
                Raylib.BeginDrawing();
                Raylib.ClearBackground(Color.RAYWHITE);

                Raylib.BeginMode3D(camera);


                Raylib.DrawTriangle3D(point1, point2, point3, Color.BLACK);



                Raylib.EndMode3D();


                //text
                Raylib.DrawRectangle(10, 10, 320, 133, Raylib.ColorAlpha(Color.SKYBLUE, 0.5f));
                Raylib.DrawRectangleLines(10, 10, 320, 133, Color.BLUE);

                Raylib.DrawText("Free camera default controls:", 20, 20, 10, Color.BLACK);
                Raylib.DrawText("- Mouse Wheel to Zoom in-out", 40, 40, 10, Color.DARKGRAY);
                Raylib.DrawText("- Mouse Wheel Pressed to Pan", 40, 60, 10, Color.DARKGRAY);
                Raylib.DrawText("- Alt + Mouse Wheel Pressed to Rotate", 40, 80, 10, Color.DARKGRAY);
                Raylib.DrawText("- Alt + Ctrl + Mouse Wheel Pressed for Smooth Zoom", 40, 100, 10, Color.DARKGRAY);


                Raylib.EndDrawing();
            

            Raylib.CloseWindow();
        
    

如果有人知道如何实现这一点，我将不胜感激。

【参考方案1】：

我不太确定您所说的 3D 三角形是什么意思，但我假设您的意思是三角棱镜。为此，您需要明确地绘制每个面。要绘制矩形边，您需要绘制两个三角形。此外，由于我们只使用三角形的正面，我们不需要禁用背面剔除。绘制三角形时，点需要排列，以便在看脸时，点按顺时针顺序排列。

这里是 C++ 实现，但它应该会给你一些想法；

    Camera3D camera;
    camera.position = (Vector3)10.0f, 10.0f, 10.0f; // Camera3D position
    camera.target = (Vector3)0.0f, 0.0f, 0.0f;      // Camera3D looking at point
    camera.up = (Vector3)0.0f, 1.0f, 0.0f;          // Camera3D up vector (rotation towards target)
    camera.fovy = 120.0f;                                // Camera3D field-of-view Y
    camera.type = CAMERA_PERSPECTIVE;        // Camera3D mode type

    Vector3 point1 = (Vector3)0.0f, 0.0f, 0.0f;
    Vector3 point2 = (Vector3)10.0f, 0.0f, 0.0f;
    Vector3 point3 = (Vector3)10.0f, 10.0f, 0.0f;

    Vector3 thickness = (Vector3)0, 0, -5.0f;

    Vector3 back1 = Vector3Add(point1, thickness);
    Vector3 back2 = Vector3Add(point2, thickness);
    Vector3 back3 = Vector3Add(point3, thickness);

    SetCameraMode(camera, CAMERA_FREE); // Set a free camera mode
    //rlDisableBackfaceCulling();       

    // Main game loop
    while (!WindowShouldClose())    // Detect window close button or ESC key
    
        // Update
        //----------------------------------------------------------------------------------
        // TODO: Update your variables here
        //----------------------------------------------------------------------------------
        

        // Draw
        //----------------------------------------------------------------------------------
        UpdateCamera(&camera);
        BeginDrawing();
        ClearBackground(RAYWHITE);

        BeginMode3D(camera);

            // Front face
            DrawTriangle3D(point1, point2, point3, BLACK);

            // Back face
            DrawTriangle3D(back3, back2, back1, BLACK);

            // Slanted side
            DrawTriangle3D(back1, point1, back3, BLACK);
            DrawTriangle3D(point1, point3, back3, BLACK);

            // Back side
            DrawTriangle3D(point2, back2, back3, BLACK);
            DrawTriangle3D(back3, point3, point2, BLACK);

            // Bottom side
            DrawTriangle3D(back1, back2, point2, BLACK);
            DrawTriangle3D(point2, point1, back1, BLACK);


            DrawGrid(100, 10.0);
        EndMode3D();


        EndDrawing();
        //----------------------------------------------------------------------------------
    

这是在轨道模式下的样子。

【讨论】：

非常感谢您的帮助