using OpenTK.Graphics.OpenGL;
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using OpenTK.Mathematics;
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namespace Yw.WinFrmUI.Hydro
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{
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/// <summary>
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/// 正交转换辅助类
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/// </summary>
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internal class OrthoTransformHelper
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{
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/// <summary>
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/// 屏幕坐标 To NDC坐标
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/// </summary>
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/// <param name="screenX">屏幕X坐标（左上角为原点）</param>
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/// <param name="screenY">屏幕Y坐标（左上角为原点）</param>
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/// <param name="depth">深度值（范围[0, 1]，可选）</param>
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/// <param name="viewportWidth">视口宽度</param>
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/// <param name="viewportHeight">视口高度</param>
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/// <returns></returns>
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public static Vector3 ScreenToNDC(float screenX, float screenY, float depth, int viewportWidth, int viewportHeight)
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{
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// 归一化到 [0, 1]
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float normalizedX = screenX / viewportWidth;
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float normalizedY = screenY / viewportHeight;
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// 映射到 [-1, 1]
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float ndcX = 2.0f * normalizedX - 1.0f;
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float ndcY = 1.0f - 2.0f * normalizedY; // 翻转Y轴
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float ndcZ = 2.0f * depth - 1.0f; // 深度值转换
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return new Vector3(ndcX, ndcY, ndcZ);
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}
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/// <summary>
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/// NDC坐标 To 屏幕坐标
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/// </summary>
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/// <param name="ndc">NDC坐标（X,Y ∈ [-1, 1], Z ∈ [-1, 1]）</param>
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/// <param name="viewportWidth">视口宽度</param>
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/// <param name="viewportHeight">视口高度</param>
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/// <returns></returns>
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public static Vector2 NDCToScreen(Vector3 ndc, int viewportWidth, int viewportHeight)
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{
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// X轴：[-1, 1] → [0, viewportWidth]
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float screenX = (ndc.X + 1.0f) * 0.5f * viewportWidth;
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// Y轴：[-1, 1] → [0, viewportHeight]（翻转Y轴）
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float screenY = (1.0f - (ndc.Y + 1.0f) * 0.5f) * viewportHeight;
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// Z轴（可选）：[-1, 1] → [0, 1]
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float screenZ = (ndc.Z + 1.0f) * 0.5f;
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return new Vector2(screenX, screenY);
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}
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/// <summary>
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/// 读取鼠标位置对应的深度值
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/// </summary>
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/// <param name="mouseX">屏幕坐标X（左上角为原点）</param>
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/// <param name="mouseY">屏幕坐标Y（左上角为原点）</param>
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/// <param name="viewportHeight">视口高度</param>
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/// <returns>深度值（范围[0, 1]）</returns>
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public static float GetScreenPointDepth(int mouseX, int mouseY, int viewportHeight)
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{
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// 调整Y坐标：屏幕坐标系（左上原点） → OpenGL视口坐标系（左下原点）
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int glY = viewportHeight - mouseY;
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// 读取深度值
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float[] depth = new float[1];
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GL.ReadPixels(
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mouseX, // 鼠标X坐标
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glY, // 调整后的Y坐标
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1, 1, // 读取1x1像素
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PixelFormat.DepthComponent, // 像素格式为深度分量
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PixelType.Float, // 数据类型为浮点数
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depth // 存储结果的数组
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);
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return depth[0];
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}
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/// <summary>
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/// 屏幕坐标 To 世界坐标
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/// </summary>
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/// <param name="mouseX">屏幕坐标X（左上角为原点）</param>
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/// <param name="mouseY">屏幕坐标Y（左上角为原点）</param>
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/// <param name="depth">深度值（范围[0, 1]，可选）</param>
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/// <param name="mview">视图矩阵</param>
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/// <param name="proj">投影矩阵</param>
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/// <param name="viewportWidth">视口宽度</param>
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/// <param name="viewportHeight">视口高度</param>
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/// <returns></returns>
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public static Vector3 ScreenToWorld(float mouseX, float mouseY, float depth, Matrix4 mview, Matrix4 proj, int viewportWidth, int viewportHeight)
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{
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var ndc = ScreenToNDC(mouseX, mouseY, depth, viewportWidth, viewportHeight);
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var matrix = mview * proj;
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var invert = matrix.Inverted();
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// 将NDC坐标转换为世界坐标
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var wp = Vector4.TransformRow(new Vector4(ndc, 1f), invert);
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wp /= wp.W; // 透视除法
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return new Vector3(wp.X, wp.Y, wp.Z);
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}
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/// <summary>
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/// 世界坐标 To 屏幕坐标
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/// </summary>
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/// <param name="wp">世界坐标</param>
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/// <param name="mview">视图矩阵</param>
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/// <param name="proj">投影矩阵</param>
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/// <param name="wiewportWidth">视口宽度</param>
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/// <param name="viewportHeight">视口高度</param>
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/// <returns></returns>
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public static Vector2 WorldToScreen(Vector3 wp, Matrix4 mview, Matrix4 proj, int wiewportWidth, int viewportHeight)
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{
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// 转换为齐次坐标
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var wph = new Vector4(wp, 1.0f);
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//应用矩阵
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var mvp = mview * proj;
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//裁剪坐标
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var clip = Vector4.TransformRow(wph, mvp);
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//NDC
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clip /= clip.W;
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return NDCToScreen(clip.Xyz, wiewportWidth, viewportHeight);
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}
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/// <summary>
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/// 创建射线
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/// </summary>
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/// <param name="mouseX">屏幕坐标X（左上角为原点）</param>
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/// <param name="mouseY">屏幕坐标Y（左上角为原点）</param>
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/// <param name="depth">深度值（范围[0, 1]，可选）</param>
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/// <param name="forward">观察方向</param>
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/// <param name="model">模型矩阵</param>
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/// <param name="view">视图矩阵</param>
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/// <param name="proj">投影矩阵</param>
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/// <param name="viewportWidth">视口宽度</param>
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/// <param name="viewportHeight">视口高度</param>
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public static Ray3 CreateRay
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(
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float mouseX,
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float mouseY,
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float depth,
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Vector3 forward,
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Matrix4 model,
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Matrix4 view,
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Matrix4 proj,
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int viewportWidth,
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int viewportHeight
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)
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{
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var mview = view * model;
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var origins = ScreenToWorld(mouseX, mouseY, depth, mview, proj, viewportWidth, viewportHeight);
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return new Ray3(origins, forward);
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}
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/// <summary>
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/// 创建射线
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/// </summary>
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/// <param name="mouseX">屏幕坐标X（左上角为原点）</param>
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/// <param name="mouseY">屏幕坐标Y（左上角为原点）</param>
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/// <param name="model">模型矩阵</param>
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/// <param name="view">视图矩阵</param>
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/// <param name="proj">投影矩阵</param>
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/// <param name="viewportWidth">视口宽度</param>
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/// <param name="viewportHeight">视口高度</param>
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public static Ray3 CreateRay2
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(
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float mouseX,
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float mouseY,
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Matrix4 model,
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Matrix4 view,
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Matrix4 proj,
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int viewportWidth,
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int viewportHeight
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)
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{
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var mview = view * model;
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var near = ScreenToWorld(mouseX, mouseY, 0f, mview, proj, viewportWidth, viewportHeight);
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var far = ScreenToWorld(mouseX, mouseY, 1f, mview, proj, viewportWidth, viewportHeight);
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var direction = (far - near).Normalized();
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return new Ray3(near, direction);
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}
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}
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}
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