以前写的一个类，用OPENGL导入MD2模型，带关键桢动画

关键桢动画的原理就是每一桢都保存一组模型的顶点
优点是实现起来简单，缺点明显,浪费空间,动画不算逼真
现在已经被骨骼动画取代了,但是骨骼动画里也有关键桢(骨骼节点的)
所以了解一下关键桢的实现也有必要
MD2、MD3这种流行的格式就不多废话了
MD2只支持关键桢,并且面数有限制,现在已经被支持骨骼动画的MD3取代了,MD3的实现在http://www.sulaco.co.za/opengl.htm上有下载
MD2的我没找到(难道是过时了?呵呵)
索性自己找了个MD2的格式说明，自己写了一个
比起MD3和3DS等模型的导入,MD2就简单多了(感觉比OBJ还简单,虽然OBJ没有动画)

用MD2来学习关键桢动画,感觉还比较合适
好了，废话不多说了,看代码吧
unit MD2Loader;
interface
uses
Windows, Dialogs, OpenGL, SysUtils, Classes, Textures;
const
MAX_TRIANGLES = 4096;
MAX_VERTS = 2048;
MAX_FRAMES = 512;
MAX_MD2SKINS = 32;
MAX_SKINNAME = 64;
MD2Magic=844121161;//MD2的标志

type
//MD2开头的就是MD2文件里的块结构
//Header比较重要，基本上MD2所有的信息都在这里面了
//不过也很简单，对于不关心的块，根据各自的Offset跳过去就行了
//Header
TMD2Header = record
MagicNum: GLint;
Version: GLint;
SkinWidth: GLint;
SkinHeight: GLint;
FrameSize: GLint;
SkinsNum: GLint;
VerticesNum: GLint;
TexCoordsNum: GLint;
TrianglesNum: GLint;
GLCommandsNum: GLint;
FramesNum: GLint;
SkinsOffset: GLint;
TexCoordsOffset: GLint;
TrianglesOffset: GLint;
FramesOffset: GLint;
GlCommandsOffset: GLint;
FileSize: GLint;
end;
//顶点结构
TMD2Ver = record
x, y, z, l: Byte;
end;
TVertice = record
x, y, z: GLfloat;
end;
TTexCoord = record
u, v: GLshort;
end;
TMD2TexCoord = record
u, v: GLfloat;
end;

//桢
TMD2Frame = record
Scale: TVertice;
Trans: TVertice;
Name: array[0..15] of Char;
Verts: array[0..MAX_VERTS - 1] of TMD2Ver;
end;
TFrame = record
Name: string;
Verts: array of TVertice;
end;
//三角形
TMD2Tri = record
VertIndex: array[0..2] of GLushort; //顶点索引
TexIndex: array[0..2] of GLushort; //纹理索引
end;
TMD2 = class(TObject)
//private
FHeader: TMD2Header;
FFrames: array of TFrame; //桢
FTriangles: array of TMD2Tri; //三角形
FTexCoords: array of TMD2TexCoord;
Texture: gluint;
ModelZoom: glfloat;
public
constructor Create; //构造函数
destructor Destroy; override; //析构函数
function LoadFile(fname: string; texName: string): Boolean;
procedure MD2Draw(frameID: integer); virtual;
procedure MD2Init; virtual;
end;
procedure glBindTexture(Target: GLenum; Texture: GLuint); stdcall; external opengl32;
implementation
{ TMD2File }
constructor TMD2.Create;
begin
ModelZoom := 2;
end;
destructor TMD2.Destroy;
begin
end;
function TMD2.LoadFile(fname: string; texName: string): Boolean;
var
modelfile: THandle;
i, j: integer;
Tri: TMD2Tri;
tex: array[0..MAX_VERTS] of TTexCoord;
frame: TMD2Frame;
begin
result := false;
glEnable(GL_TEXTURE_2D);
LoadTexture(texName, Texture, False);
modelfile := FileOpen(fname, fmOpenRead);
if modelfile <= 0 then
begin
showmessage('load file erro');
exit;
end;
//读入Header
if FileRead(modelfile, FHeader, sizeof(FHeader)) <= 0 then
begin
showmessage('Read Header erro');
exit;
end;
if FHeader.MagicNum <> MD2Magic then
begin
showmessage('Not MD2 File');
exit;
end;
//设置Frame长度
setlength(FFrames, FHeader.FramesNum);
//设置Tri长度
setlength(FTriangles, FHeader.TrianglesNum);
//
SetLength(FTexCoords, FHeader.TexCoordsNum);
for i := 0 to FHeader.FramesNum - 1 do
//设置每个 Frame的Verts长度
setlength(FFrames[i].Verts, FHeader.VerticesNum);
//定位到TexCoords
if FileSeek(modelfile, FHeader.TexCoordsOffset, 0) <= 0 then
begin
showmessage('Seek TexCoords erro');
exit;
end;
if FileRead(modelfile, Tex, FHeader.TrianglesOffset - FHeader.SkinsOffset) <= 0 then
begin
showmessage('tex erro');
exit;
end;
for i := 0 to FHeader.TexCoordsNum - 1 do
begin
FTexCoords[i].u := tex[i].u / FHeader.SkinWidth;
FTexCoords[i].v := 1 - tex[i].v / FHeader.SkinHeight;
end;
//定位到Triangles
if FileSeek(modelfile, FHeader.TrianglesOffset, 0) <= 0 then
begin
showmessage('Seek Triangles erro');
exit;
end;
for i := 0 to FHeader.TrianglesNum - 1 do
begin
if FileRead(modelfile, Tri, sizeof(TMD2Tri)) <= 0 then
begin
showmessage('Tri erro');
exit;
end;
FTriangles[i].VertIndex[0] := Tri.VertIndex[0];
FTriangles[i].VertIndex[1] := Tri.VertIndex[1];
FTriangles[i].VertIndex[2] := Tri.VertIndex[2];
FTriangles[i].TexIndex[0] := Tri.TexIndex[0];
FTriangles[i].TexIndex[1] := Tri.TexIndex[1];
FTriangles[i].TexIndex[2] := Tri.TexIndex[2];
end;
//定位到 Frames
if FileSeek(modelfile, FHeader.FramesOffset, 0) <= 0 then
begin
showmessage('Seek frame erro');
exit;
end;
ZeroMemory(@frame, Sizeof(frame));
for i := 0 to FHeader.FramesNum - 1 do
begin
if FileRead(modelfile, frame, FHeader.FrameSize) <= 0 then
begin
showmessage('frame erro');
exit;
end;
FFrames[i].Name := frame.Name;
for j := 0 to FHeader.VerticesNum - 1 do
begin
FFrames[i].Verts[j].x := (frame.Verts[j].x * frame.Scale.x + frame.Trans.x) / ModelZoom;
FFrames[i].Verts[j].y := (frame.Verts[j].y * frame.Scale.y + frame.Trans.y) / ModelZoom;
FFrames[i].Verts[j].z := (frame.Verts[j].z * frame.Scale.z + frame.Trans.z) / ModelZoom;
end;
end;
MD2Init;
end;
procedure TMD2.MD2Draw(frameID: integer);
var
i: integer;
begin
if frameID >= FHeader.FramesNum then
frameID := -1;
if frameID < 0 then exit;
glBindTexture(GL_TEXTURE_2D, texture); // 选择纹理
glBegin(GL_TRIANGLES);
for i := 0 to FHeader.TrianglesNum - 1 do
begin
glTexCoord2fv(@FTexCoords[FTriangles[i].TexIndex[0]]);
glVertex3fv(@FFrames[frameID].Verts[FTriangles[i].VertIndex[0]]);
glTexCoord2fv(@FTexCoords[FTriangles[i].TexIndex[1]]);
glVertex3fv(@FFrames[frameID].Verts[FTriangles[i].VertIndex[1]]);
glTexCoord2fv(@FTexCoords[FTriangles[i].TexIndex[2]]);
glVertex3fv(@FFrames[frameID].Verts[FTriangles[i].VertIndex[2]]);
end;
glEnd();
end;
procedure TMD2.MD2Init;
begin
end;
end.

Textures是一个纹理载入单元，提供的函数只有一个,就是LoadTexture,支持BMP、JPG和TGA三种格式
在http://www.sulaco.co.za/opengl.htm可以下到
用的时候,只要在初始化的时候创建TMD2对象,指定纹理,然后设置一个变量纪录关键桢
在渲染函数里调用一下对象的MD2Draw就行了
如果想控制动画,控制纪录关键桢的变量就行了
下面是一个我用这个类载入的一个MD2模型的动画的截图