TMesh -生成三维形状并计算法线
TMesh -生成三维形状并计算法线
提问于 2021-11-16 16:20:32
我试着理解3d是如何工作的，我已经创建了3d形状，例如多维数据集。
我填写mesh.data.VertexBuffer.Vertices和mesh.data.IndexBuffer。屏幕上一切看上去都很好，但阴影没有问题。
我不明白如何为顶点提供法线？我可以考虑三角形的法线，但我无法想象单个顶点。一个垂直线可以由多个三角形共享，是吗？例如，对于立方体，三面墙可以共用一个角线。
也许我的理解是错的。
问题是：
，
- ，对于立方体，应该像现在一样只有8点吗？在indexbuffer.
- Or中使用它们，我应该对每个三角形都有单独的点，即使它们和其他三角形点有相同的坐标，也能计算法线吗？例如，对于立方体，我应该有：
6 walls * 4 points = 24 points而不是我目前的8只？
更新
unit UnitMain;
interface
uses
System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,
FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs, FMX.Viewport3D, System.Math.Vectors, FMX.Types3D,
FMX.Controls3D, FMX.Objects3D, FMX.MaterialSources;
type
TFormCube = class(TForm)
Viewport3D1: TViewport3D;
Camera1: TCamera;
Light1: TLight;
Mesh1: TMesh;
LightMaterialSource1: TLightMaterialSource;
LightMaterialSource2: TLightMaterialSource;
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
FormCube: TFormCube;
implementation
{$R *.fmx}
procedure TFormCube.FormCreate(Sender: TObject);
Var idx: Integer;
begin
Mesh1.Data.VertexBuffer.Length:= 8;
Mesh1.Data.VertexBuffer.Vertices[0]:= Point3d(1, 1, 1);
Mesh1.Data.VertexBuffer.Vertices[1]:= Point3d(1, -1, 1);
Mesh1.Data.VertexBuffer.Vertices[2]:= Point3d(-1, -1, 1);
Mesh1.Data.VertexBuffer.Vertices[3]:= Point3d(-1, 1, 1);
Mesh1.Data.VertexBuffer.Vertices[4]:= Point3d(1, 1, -1);
Mesh1.Data.VertexBuffer.Vertices[5]:= Point3d(1, -1, -1);
Mesh1.Data.VertexBuffer.Vertices[6]:= Point3d(-1, -1, -1);
Mesh1.Data.VertexBuffer.Vertices[7]:= Point3d(-1, 1, -1);
Mesh1.Data.IndexBuffer.Length:= 8*2*3;
//front
idx:= 0;
Mesh1.Data.IndexBuffer[idx + 0]:= 0;
Mesh1.Data.IndexBuffer[idx + 1]:= 3;
Mesh1.Data.IndexBuffer[idx + 2]:= 2;
inc(idx, 3);
Mesh1.Data.IndexBuffer[idx + 0]:= 0;
Mesh1.Data.IndexBuffer[idx + 1]:= 2;
Mesh1.Data.IndexBuffer[idx + 2]:= 1;
//right
inc(idx, 3);
Mesh1.Data.IndexBuffer[idx + 0]:= 4;
Mesh1.Data.IndexBuffer[idx + 1]:= 0;
Mesh1.Data.IndexBuffer[idx + 2]:= 1;
inc(idx, 3);
Mesh1.Data.IndexBuffer[idx + 0]:= 4;
Mesh1.Data.IndexBuffer[idx + 1]:= 1;
Mesh1.Data.IndexBuffer[idx + 2]:= 5;
//back
inc(idx, 3);
Mesh1.Data.IndexBuffer[idx + 0]:= 7;
Mesh1.Data.IndexBuffer[idx + 1]:= 4;
Mesh1.Data.IndexBuffer[idx + 2]:= 5;
inc(idx, 3);
Mesh1.Data.IndexBuffer[idx + 0]:= 7;
Mesh1.Data.IndexBuffer[idx + 1]:= 5;
Mesh1.Data.IndexBuffer[idx + 2]:= 6;
//left
inc(idx, 3);
Mesh1.Data.IndexBuffer[idx + 0]:= 3;
Mesh1.Data.IndexBuffer[idx + 1]:= 7;
Mesh1.Data.IndexBuffer[idx + 2]:= 6;
inc(idx, 3);
Mesh1.Data.IndexBuffer[idx + 0]:= 3;
Mesh1.Data.IndexBuffer[idx + 1]:= 6;
Mesh1.Data.IndexBuffer[idx + 2]:= 2;
//top
inc(idx, 3);
Mesh1.Data.IndexBuffer[idx + 0]:= 4;
Mesh1.Data.IndexBuffer[idx + 1]:= 7;
Mesh1.Data.IndexBuffer[idx + 2]:= 3;
inc(idx, 3);
Mesh1.Data.IndexBuffer[idx + 0]:= 4;
Mesh1.Data.IndexBuffer[idx + 1]:= 3;
Mesh1.Data.IndexBuffer[idx + 2]:= 0;
//bottom
inc(idx, 3);
Mesh1.Data.IndexBuffer[idx + 0]:= 1;
Mesh1.Data.IndexBuffer[idx + 1]:= 2;
Mesh1.Data.IndexBuffer[idx + 2]:= 6;
inc(idx, 3);
Mesh1.Data.IndexBuffer[idx + 0]:= 1;
Mesh1.Data.IndexBuffer[idx + 1]:= 6;
Mesh1.Data.IndexBuffer[idx + 2]:= 5;
end;
end.和dfm
object FormCube: TFormCube
Left = 0
Top = 0
Caption = 'Cube'
ClientHeight = 823
ClientWidth = 1166
FormFactor.Width = 320
FormFactor.Height = 480
FormFactor.Devices = [Desktop]
OnCreate = FormCreate
DesignerMasterStyle = 0
object Viewport3D1: TViewport3D
Align = Client
Camera = Camera1
Color = claBlack
Size.Width = 1166.000000000000000000
Size.Height = 823.000000000000000000
Size.PlatformDefault = False
UsingDesignCamera = False
object Camera1: TCamera
AngleOfView = 45.000000000000000000
Position.X = -2.000000000000000000
Position.Y = -2.000000000000000000
Position.Z = -10.000000000000000000
Width = 1.000000000000000000
Height = 1.000000000000000000
Depth = 1.000000000000000000
end
object Light1: TLight
Color = claWhite
LightType = Directional
SpotCutOff = 180.000000000000000000
Position.X = -9.222618103027344000
Position.Y = 2.758471012115479000
RotationAngle.Y = 21.211906433105470000
Width = 1.000000000000000000
Height = 1.000000000000000000
Depth = 1.000000000000000000
Quanternion = '(0,-0.184053480625153,0,-0.982916116714478)'
end
object Mesh1: TMesh
Width = 1.000000000000000000
Height = 1.000000000000000000
Depth = 1.000000000000000000
TwoSide = True
MaterialSource = LightMaterialSource2
end
object LightMaterialSource1: TLightMaterialSource
Diffuse = claRed
Ambient = claBlue
Emissive = claGreen
Specular = claWhite
Shininess = 30
Left = 280
Top = 168
end
end
object LightMaterialSource2: TLightMaterialSource
Diffuse = claWhite
Ambient = xFF202020
Emissive = claNull
Specular = xFF606060
Shininess = 30
Left = 248
Top = 256
end
end回答 1
Stack Overflow用户
发布于 2021-11-16 21:07:15
看起来第二个选项是真的。
我认为这是浪费资源，需要更多的点数。
而不是8点，后者从第一个角度描述了qube good
我需要24积分(6 walls * 4 points = 24 points)。
在此基础上，通过乘积法得到简单的法线。
结果现在看起来很好，对于更复杂的形状也是如此。
结论与Blender 2.93一致，为立方体出口24分。
<float_array id="Cube-mesh-positions-array" count="24">1 1 1 1 1 -1 1 -1 1 1 -1 -1 -1 1 1 -1 1 -1 -1 -1 1 -1 -1 -1</float_array>页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/69992685
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