john7rv

OpenSourceのpasGltfライブラリの使い方の解説です
かなり大きく難解なライブラリなのでページを作りました
ほぼ自分用です
pasGltfViewer.dpr
draw関数内の
629行から
行列を使ったカメラの設定

  ViewMatrix:=MatrixLookAt(Vector3Add(Center,
                                      Vector3ScalarMul(Vector3Normalize(Vector3(sin(CameraRotationX*PI*2.0)*cos(-CameraRotationY*PI*2.0),
                                                                                sin(-CameraRotationY*PI*2.0),
                                                                                cos(CameraRotationX*PI*2.0)*cos(-CameraRotationY*PI*2.0))),
                                                        Max(Max(Bounds[0],Bounds[1]),Bounds[2])*3.0*Zoom)),
                           Center,
                           Vector3(0.0,1.0,0.0));

  ProjectionMatrix:=Matrix4x4ProjectionReversedZ(45.0,ViewPortWidth/ViewPortHeight,1e-3);
 end;

646行
アニメーションの設定

if assigned(GLTFInstance) then begin
  GLTFInstance.Scene:=SceneIndex;
  GLTFInstance.Animation:=AnimationIndex;
  if (LastAnimationIndex<>AnimationIndex) and Shadows then begin
   LastAnimationIndex:=AnimationIndex;
// GLTFInstance.UpdateWorstCaseStaticBoundingBox;
  end;
  if AnimationTime<AnimationBeginTime then begin
   AnimationTime:=AnimationBeginTime;
  end;
  if AnimationTime>AnimationEndTime then begin
   AnimationTime:=Modulo(AnimationTime-AnimationBeginTime,AnimationEndTime-AnimationBeginTime)+AnimationBeginTime;
   if AnimationTime>=AnimationEndTime then begin
    AnimationTime:=AnimationEndTime;
   end;
  end;
  GLTFInstance.AnimationTime:=AnimationTime;
  GLTFInstance.Update;
  GLTFInstance.Upload;
 end;

680行
スカイボックスやテクスチャやその他OpenGLの設定

begin
  glBindFrameBuffer(GL_FRAMEBUFFER,HDRSceneFBO.FBOs[0]);
  glDrawBuffer(GL_COLOR_ATTACHMENT0);
  glViewport(0,0,HDRSceneFBO.Width,HDRSceneFBO.Height);
  glClearColor(0.0,0.0,0.0,0.0);
  glClearDepth(0.0);
  glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);
  glClipControl(GL_LOWER_LEFT,GL_ZERO_TO_ONE);
  glDepthFunc(GL_GEQUAL);
  SkyBoxViewProjectionMatrix:=ViewMatrix;
  SkyBoxViewProjectionMatrix[3]:=0.0;
  SkyBoxViewProjectionMatrix[7]:=0.0;
  SkyBoxViewProjectionMatrix[11]:=0.0;
  SkyBoxViewProjectionMatrix[12]:=0.0;
  SkyBoxViewProjectionMatrix[13]:=0.0;
  SkyBoxViewProjectionMatrix[14]:=0.0;
  SkyBoxViewProjectionMatrix:=MatrixMul(SkyBoxViewProjectionMatrix,ProjectionMatrix);
  begin
   glDisable(GL_DEPTH_TEST);
   glDisable(GL_CULL_FACE);
   glActiveTexture(GL_TEXTURE0);
   glBindTexture(GL_TEXTURE_CUBE_MAP,EnvMapTextureHandle);
   EnvMapDrawShader.Bind;
   glUniform1i(EnvMapDrawShader.uTexture,0);
   glUniformMatrix4fv(EnvMapDrawShader.uViewProjectionMatrix,1,false,@SkyBoxViewProjectionMatrix);
   glBindVertexArray(EmptyVertexArrayObjectHandle);
   glDrawArrays(GL_TRIANGLES,0,36);
   glBindVertexArray(0);
   EnvMapDrawShader.Unbind;
  end;
  begin
   glActiveTexture(GL_TEXTURE0);
   glBindTexture(GL_TEXTURE_2D,BRDFLUTFBO.TextureHandles[0]);
   glActiveTexture(GL_TEXTURE1);
   glBindTexture(GL_TEXTURE_CUBE_MAP,EnvMapFBO.TextureHandles[0]);
   glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR_MIPMAP_LINEAR);
   glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
   if Shadows then begin
    glActiveTexture(GL_TEXTURE2);
    glBindTexture(GL_TEXTURE_2D,ShadowMapFBOs[2].TextureHandles[0]);
   end;
   glActiveTexture(GL_TEXTURE0);
   glEnable(GL_DEPTH_TEST);
   glEnable(GL_CULL_FACE);
   glCullFace(GL_BACK);
   for ShadingShader in ShadingShaders do begin
    ShadingShader.Bind;
    glUniform1i(ShadingShader.uEnvMapMaxLevel,Min(EnvMapFBO.WorkMaxLevel,16));
    glUniform1i(ShadingShader.uShadows,ord(Shadows) and 1);
    ShadingShader.Unbind;
   end;
   if assigned(GLTFInstance) then begin
    GLTFInstance.DrawFinal(TPasGLTF.TMatrix4x4(Pointer(@ModelMatrix)^),
                           TPasGLTF.TMatrix4x4(Pointer(@ViewMatrix)^),
                           TPasGLTF.TMatrix4x4(Pointer(@ProjectionMatrix)^),
                           ShadingShaders[false,false],
                           ShadingShaders[false,true],
                           ShadingShaders[true,false],
                           ShadingShaders[true,true]);
    if ShowJoints then begin
     GLTFInstance.DrawJoints(TPasGLTF.TMatrix4x4(Pointer(@ModelMatrix)^),
                             TPasGLTF.TMatrix4x4(Pointer(@ViewMatrix)^),
                             TPasGLTF.TMatrix4x4(Pointer(@ProjectionMatrix)^),
                             SolidColorShader);
    end;
   end;
  end;
  glClipControl(GL_LOWER_LEFT,GL_NEGATIVE_ONE_TO_ONE);
 end;

749行
シェーダーとglDrawArrayでの描画

 begin
  glBindFrameBuffer(GL_FRAMEBUFFER,LDRSceneFBO.FBOs[0]);
  glDrawBuffer(GL_COLOR_ATTACHMENT0);
  glViewport(0,0,LDRSceneFBO.Width,LDRSceneFBO.Height);
  glClearColor(0.0,0.0,0.0,0.0);
  glClear(GL_COLOR_BUFFER_BIT);
  glDisable(GL_DEPTH_TEST);
  glDisable(GL_CULL_FACE);
  glActiveTexture(GL_TEXTURE0);
  glBindTexture(GL_TEXTURE_2D,HDRSceneFBO.TextureHandles[0]);
  HDRToLDRShader.Bind;
  glUniform1i(HDRToLDRShader.uTexture,0);
  glBindVertexArray(EmptyVertexArrayObjectHandle);
  glDrawArrays(GL_TRIANGLES,0,3);
  glBindVertexArray(0);
  HDRToLDRShader.Unbind;
 end;

760行
描画部分

begin
  glBindFrameBuffer(GL_FRAMEBUFFER,0);
  glDrawBuffer(GL_BACK);
  glViewport(0,0,ViewPortWidth,ViewPortHeight);
  glClearColor(0.0,0.0,0.0,0.0);
  glClearDepth(1.0);
  glViewport(ViewPortX,ViewPortY,ViewPortWidth,ViewPortHeight);
  glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);
  glDisable(GL_DEPTH_TEST);
  glDisable(GL_CULL_FACE);
  glActiveTexture(GL_TEXTURE0);
  glBindTexture(GL_TEXTURE_2D,LDRSceneFBO.TextureHandles[0]);
  AntialiasingShader.Bind;
  glUniform1i(AntialiasingShader.uTexture,0);
  glBindVertexArray(EmptyVertexArrayObjectHandle);
  glDrawArrays(GL_TRIANGLES,0,3);
  glBindVertexArray(0);
  AntialiasingShader.Unbind;
  glDisable(GL_BLEND);
  ConsoleInstance.Draw(DeltaTime,ViewPortX,ViewPortY,ViewPortWidth,ViewPortHeight);
  glEnable(GL_DEPTH_TEST);
 end;