使用 Unity 绘制应用程序

Question

在过去的一周里，我一直在寻找一种使用 Unity 创建应用程序的方法，我将能够在其中创建绘图。是这样的：我尝试了几种模拟绘图的方法，但都没有达到我的预期。您认为实现这一目标的推荐方法是什么？我尝试使用 SetPixel 和 GetPixel，但由于在运行时编辑纹理可能非常慢，我正在寻找更好的方法（如果有的话）。谢谢。

Answer 1

我没有用相对较大的纹理对此进行测试，但我用它画了一张快乐的脸，我有评论解释代码中发生了什么，使用它的最佳方法是使用 Unity 菜单并创建一个 RawImage，然后附加此脚本:

using UnityEngine;

using UnityEngine.UI;

[RequireComponent(typeof(RawImage))]

public class PaintCanvas : MonoBehaviour

{

    RectTransform rt;

    RawImage ri;

    Vector3 bottomLeft = Vector3.zero;

    Vector3 topRight = Vector3.zero;

    Texture2D canvas;

    int width = 0;

    int height = 0;

    // Start is called before the first frame update

    void Start()

    {

        // Getting the RectTransform, since this is a RawImage, which exists on the canvas and should have a rect transform

        rt = GetComponent<RectTransform>();

        if (rt != null)

        {

            GetWorldCorners();

        }

        // RawImage that we are going to be updating for our paint application.

        ri = GetComponent<RawImage>();

        if (ri != null)

        {

            CreateTexture2D();

        }

    }

    // Update is called once per frame

    void Update()

    {

        // Make sure our stuff is valid

        if (rt != null)

        {

            if(ri != null)

            {

                HandleInput();

            }

        }

    }

    void HandleInput()

    {

        // Since we can only paint on the canvas if the mouse button is press

        // May be best to revise this so the tool has a call back for example a 

        // fill tool selected would call its own "Handle" method,

        if(Input.GetMouseButtonDown(0) || Input.GetMouseButton(0))

        {

            Vector2Int mousePos = Vector2Int.zero;

            // We have input, lets convert the mouse position to be relative to the canvas

            ConvertMousePosition(ref mousePos);

            // Checking that our mouse is in bounds, which is stored in our height and width variable and as long as it has a "positive value"

            if(MouseIsInBounds(mousePos))

            {

                // This method could be removed to be the tool method I mention above

                // you would pass in the mousePosition, and color similar to this.

                // This way each tool would be its "own" component that would be activated

                // through some form of UI.

                PaintTexture(mousePos, Color.black); // Also the color you want would be here to...

            }

            Debug.Log(mousePos);

        }

    }

    void PaintTexture(Vector2Int pos, Color color)

    {

        // In our method we don't allow transparency and we are just replacing the pixel,

        canvas.SetPixel(pos.x, pos.y, color);

        // Applying out change, we dont want to mip levels.

        // If you are doing some blending or transparency stuff that would be handled by your tool

        canvas.Apply(false);

    }

    bool MouseIsInBounds(Vector2Int mousePos)

    {

        // The position is already relative to the texture so if it is >= to 0 and less then the texture

        // width and height it is in bounds.

        if(mousePos.x >= 0 && mousePos.x < width)

        {

            if (mousePos.y >= 0 && mousePos.y < height)

            {

                return true;

            }

        }

        return false;

    }

    void ConvertMousePosition(ref Vector2Int mouseOut)

    {

        // The mouse Position, and the RawImage position are returned in the same space

        // So we can just update based off of that

        mouseOut.x = Mathf.RoundToInt(Input.mousePosition.x - bottomLeft.x);

        mouseOut.y = Mathf.RoundToInt(Input.mousePosition.y - bottomLeft.y);

    }

    void CreateTexture2D()

    {

        // Creating our "Draw" texture to be the same size as our RawImage.

        width = Mathf.RoundToInt(topRight.x - bottomLeft.x);

        height = Mathf.RoundToInt(topRight.y - bottomLeft.y);

        canvas = new Texture2D(width, height);

        ri.texture = canvas;

    }

    void GetWorldCorners()

    {

        if (rt != null)

        {

            Vector3[] corners = new Vector3[4];

            rt.GetWorldCorners(corners);

            // Setting our corners  based on the fact GetCorners returns them in clockwise order starting from BL TL TR BR.

            bottomLeft = corners[0];

            topRight = corners[2];

        }

    }

}

我只想指出，取决于你的规模，你移动鼠标的速度有多快，你最终可能会得到点，这是因为这个算法只更新每帧鼠标经过的像素，如果你移动鼠标快于 1 px每帧你都会有间隙，这可以通过存储最后一帧的 mousePosition 来解决，获取这一帧的新位置，并创建一条线，然后更新该线上的所有点。