[7] 金字塔(Pyramid)图形的生成算法

顶点数据的生成

 bool                        YfBuildPyramidVertices
 (
     Yreal                   width,
     Yreal                   length,
     Yreal                   height,
     YeOriginPose            originPose,
     Yuint                   vertexStriding,
     Yuint                   vertexPos,
     void*                   pVerticesBuffer
 )
 {
     if (!pVerticesBuffer)
     {
         return false;
     }

     Yuint numVertices  = ;

     char* vertexPtr   = (char*)pVerticesBuffer + vertexPos;
     YsVector3* curVertexPtr   = NULL;
     Yuint nOffset = ;

     YsVector3 vOriginOffset(-width / , -height / , -length / );
     if (originPose == YE_ORIGIN_POSE_TOP)
     {
         vOriginOffset.y = -height;
     }
     else if (originPose == YE_ORIGIN_POSE_BOTTOM)
     {
         vOriginOffset.y = 0.0f;
     }

     // 底四个顶点
     for (Yuint j = ; j < ; j++)
     {
         for (Yuint i = ; i < ; i++)
         {
             nOffset = (j* + i) * vertexStriding;
             curVertexPtr = (YsVector3*)(vertexPtr + nOffset);
             curVertexPtr->x = width*i + vOriginOffset.x;
             curVertexPtr->y = vOriginOffset.y;
             curVertexPtr->z = length*j + vOriginOffset.z;
         }
     }

     // 顶尖顶点
     nOffset =  * vertexStriding;
     curVertexPtr = (YsVector3*)(vertexPtr + nOffset);
     curVertexPtr->x = 0.0f;
     curVertexPtr->y = height + vOriginOffset.y;
     curVertexPtr->z = 0.0f;

     return true;
 }     

三角形索引数据的生成

 bool                        YfBuildPyramidTriIndices
 (
     YeIndexType             indexType,
     Yuint                   indexStriding,
     Yuint                   indexPos,
     void*                   pTriIndicesBuffer
 )
 {
     if (!pTriIndicesBuffer)
     {
         return false;
     }

     char* indexPtr = (char*)pTriIndicesBuffer + indexPos;
     if (indexType == YE_INDEX_16_BIT)
     {
         YsTriIndex16* triIndexPtr = NULL;

         // bottom
         triIndexPtr = (YsTriIndex16*)(indexPtr + *indexStriding);
         triIndexPtr->index0 = ; triIndexPtr->index1 = ; triIndexPtr->index2 = ;
         triIndexPtr = (YsTriIndex16*)(indexPtr + *indexStriding);
         triIndexPtr->index0 = ; triIndexPtr->index1 = ; triIndexPtr->index2 = ;

         // 4 face
         triIndexPtr = (YsTriIndex16*)(indexPtr + *indexStriding);
         triIndexPtr->index0 = ; triIndexPtr->index1 = ; triIndexPtr->index2 = ;
         triIndexPtr = (YsTriIndex16*)(indexPtr + *indexStriding);
         triIndexPtr->index0 = ; triIndexPtr->index1 = ; triIndexPtr->index2 = ;
         triIndexPtr = (YsTriIndex16*)(indexPtr + *indexStriding);
         triIndexPtr->index0 = ; triIndexPtr->index1 = ; triIndexPtr->index2 = ;
         triIndexPtr = (YsTriIndex16*)(indexPtr + *indexStriding);
         triIndexPtr->index0 = ; triIndexPtr->index1 = ; triIndexPtr->index2 = ;
     }
     else
     {
         YsTriIndex32* triIndexPtr = NULL;

         // bottom
         triIndexPtr = (YsTriIndex32*)(indexPtr + *indexStriding);
         triIndexPtr->index0 = ; triIndexPtr->index1 = ; triIndexPtr->index2 = ;
         triIndexPtr = (YsTriIndex32*)(indexPtr + *indexStriding);
         triIndexPtr->index0 = ; triIndexPtr->index1 = ; triIndexPtr->index2 = ;

         // 4 face
         triIndexPtr = (YsTriIndex32*)(indexPtr + *indexStriding);
         triIndexPtr->index0 = ; triIndexPtr->index1 = ; triIndexPtr->index2 = ;
         triIndexPtr = (YsTriIndex32*)(indexPtr + *indexStriding);
         triIndexPtr->index0 = ; triIndexPtr->index1 = ; triIndexPtr->index2 = ;
         triIndexPtr = (YsTriIndex32*)(indexPtr + *indexStriding);
         triIndexPtr->index0 = ; triIndexPtr->index1 = ; triIndexPtr->index2 = ;
         triIndexPtr = (YsTriIndex32*)(indexPtr + *indexStriding);
         triIndexPtr->index0 = ; triIndexPtr->index1 = ; triIndexPtr->index2 = ;
     }

     return true;
 }     

线框索引数据的生成

 bool                        YfBuildPyramidWireIndices
 (
     YeIndexType             indexType,
     Yuint                   indexStriding,
     Yuint                   indexPos,
     void*                   pWireIndicesBuffer
 )
 {
     if (!pWireIndicesBuffer)
     {
         return false;
     }

     Yuint numVertices = ;
     Yuint numLines    = ;
     if (indexType == YE_INDEX_16_BIT &&
         numVertices > YD_MAX_UNSIGNED_INT16)
     {
         return false;
     }

     // 索引赋值
     char* indexPtr = (char*)pWireIndicesBuffer + indexPos;
     Yuint nOffset = ;
     if (indexType == YE_INDEX_16_BIT)
     {
         YsLineIndex16* lineIndexPtr = NULL;

         // bottom
         lineIndexPtr = (YsLineIndex16*)(indexPtr + *indexStriding);
         lineIndexPtr->index0 = ; lineIndexPtr->index1 = ;
         lineIndexPtr = (YsLineIndex16*)(indexPtr + *indexStriding);
         lineIndexPtr->index0 = ; lineIndexPtr->index1 = ;
         lineIndexPtr = (YsLineIndex16*)(indexPtr + *indexStriding);
         lineIndexPtr->index0 = ; lineIndexPtr->index1 = ;
         lineIndexPtr = (YsLineIndex16*)(indexPtr + *indexStriding);
         lineIndexPtr->index0 = ; lineIndexPtr->index1 = ; 

         // 4 lines
         lineIndexPtr = (YsLineIndex16*)(indexPtr + *indexStriding);
         lineIndexPtr->index0 = ; lineIndexPtr->index1 = ;
         lineIndexPtr = (YsLineIndex16*)(indexPtr + *indexStriding);
         lineIndexPtr->index0 = ; lineIndexPtr->index1 = ;
         lineIndexPtr = (YsLineIndex16*)(indexPtr + *indexStriding);
         lineIndexPtr->index0 = ; lineIndexPtr->index1 = ;
         lineIndexPtr = (YsLineIndex16*)(indexPtr + *indexStriding);
         lineIndexPtr->index0 = ; lineIndexPtr->index1 = ;
     }
     else
     {
         YsLineIndex32* lineIndexPtr = NULL;

         // bottom
         lineIndexPtr = (YsLineIndex32*)(indexPtr + *indexStriding);
         lineIndexPtr->index0 = ; lineIndexPtr->index1 = ;
         lineIndexPtr = (YsLineIndex32*)(indexPtr + *indexStriding);
         lineIndexPtr->index0 = ; lineIndexPtr->index1 = ;
         lineIndexPtr = (YsLineIndex32*)(indexPtr + *indexStriding);
         lineIndexPtr->index0 = ; lineIndexPtr->index1 = ;
         lineIndexPtr = (YsLineIndex32*)(indexPtr + *indexStriding);
         lineIndexPtr->index0 = ; lineIndexPtr->index1 = ; 

         // 4 lines
         lineIndexPtr = (YsLineIndex32*)(indexPtr + *indexStriding);
         lineIndexPtr->index0 = ; lineIndexPtr->index1 = ;
         lineIndexPtr = (YsLineIndex32*)(indexPtr + *indexStriding);
         lineIndexPtr->index0 = ; lineIndexPtr->index1 = ;
         lineIndexPtr = (YsLineIndex32*)(indexPtr + *indexStriding);
         lineIndexPtr->index0 = ; lineIndexPtr->index1 = ;
         lineIndexPtr = (YsLineIndex32*)(indexPtr + *indexStriding);
         lineIndexPtr->index0 = ; lineIndexPtr->index1 = ;
     }

     return true;
 }