[16] 螺旋面(Spire)图形的生成算法

顶点数据的生成

 bool                        YfBuildSpireVertices

 (

     Yreal                   radius,

     Yreal                   assistRadius,

     Yreal                   height,

     Yuint                   slices,

     Yuint                   stacks,

     YeOriginPose            originPose,

     Yuint                   vertexStriding,

     Yuint                   vertexPos,

     void*                   pVerticesBuffer

 )

 {

     if (stacks <  || slices <  || !pVerticesBuffer)

     {

         return false;

     }

     Yuint numVertices  =  + stacks * ;

     //Yuint numTriangles = stacks * 2;

     char* vertexPtr = (char*)pVerticesBuffer + vertexPos;

     YsVector3* curVertexPtr = NULL;

     Yuint nOffset = ;

     Yreal originOffsetY = 0.0f;

     if (originPose == YE_ORIGIN_POSE_TOP)

     {

         originOffsetY = -height;

     }

     else if (originPose == YE_ORIGIN_POSE_CENTER)

     {

         originOffsetY = -height * 0.5f;

     }

     Yreal fAngle = YD_REAL_TWAIN_PI / slices;

     Yreal angleXZ;

     Yreal posX, posZ;

     for (Yuint i = ; i <= stacks; i++)

     {

         angleXZ = i * fAngle;

         posX = yf_sin(angleXZ);

         posZ = yf_cos(angleXZ);

         nOffset = i *  * vertexStriding;

         curVertexPtr = (YsVector3*)(vertexPtr + nOffset);

         curVertexPtr->x = assistRadius * posX;

         curVertexPtr->y = height * i * 1.0f / stacks + originOffsetY;

         curVertexPtr->z = assistRadius * posZ;

         nOffset += vertexStriding;

         curVertexPtr = (YsVector3*)(vertexPtr + nOffset);

         curVertexPtr->x = radius * posX;

         curVertexPtr->y = height * i * 1.0f / stacks + originOffsetY;

         curVertexPtr->z = radius * posZ;

     }

     return true;

 }

三角形索引数据的生成

 bool                        YfBuildSpireTriIndices

 (

     Yuint                   stacks,

     YeIndexType             indexType,

     Yuint                   indexStriding,

     Yuint                   indexPos,

     void*                   pTriIndicesBuffer

 )

 {

     if (stacks <  || !pTriIndicesBuffer)

     {

         return false;

     }

     Yuint numVertices  =  + stacks * ;

     Yuint numTriangles = stacks * ;

     if (indexType == YE_INDEX_16_BIT &&

         numVertices > YD_MAX_UNSIGNED_INT16)

     {

         return false;

     }

     // 索引赋值

     char* indexPtr = (char*)pTriIndicesBuffer + indexPos;

     Yuint nOffset = ;

     if (indexType == YE_INDEX_16_BIT)

     {

         YsTriIndex16* triIndexPtr = NULL;

         for (Yuint i = ; i < stacks; i++)

         {

             nOffset =  * i * indexStriding;

             triIndexPtr = (YsTriIndex16*)(indexPtr + nOffset);

             triIndexPtr->index0 = i*;

             triIndexPtr->index1 = i* + ;

             triIndexPtr->index2 = i* + ;

             nOffset += indexStriding;

             triIndexPtr = (YsTriIndex16*)(indexPtr + nOffset);

             triIndexPtr->index0 = i*;

             triIndexPtr->index1 = i* + ;

             triIndexPtr->index2 = i* + ;

         }

     }

     else

     {

         YsTriIndex32* triIndexPtr = NULL;

         for (Yuint i = ; i < stacks; i++)

         {

             nOffset =  * i * indexStriding;

             triIndexPtr = (YsTriIndex32*)(indexPtr + nOffset);

             triIndexPtr->index0 = i*;

             triIndexPtr->index1 = i* + ;

             triIndexPtr->index2 = i* + ;

             nOffset += indexStriding;

             triIndexPtr = (YsTriIndex32*)(indexPtr + nOffset);

             triIndexPtr->index0 = i*;

             triIndexPtr->index1 = i* + ;

             triIndexPtr->index2 = i* + ;

         }

     }

     return true;

 } 

线框索引数据的生成

 bool                        YfBuildSpireWireIndices

 (

     Yuint                   stacks,

     YeIndexType             indexType,

     Yuint                   indexStriding,

     Yuint                   indexPos,

     void*                   pWireIndicesBuffer

 )

 {

     if (stacks <  || !pWireIndicesBuffer)

     {

         return false;

     }

     Yuint numVertices =  + stacks * ;

     Yuint numLines    =  + stacks * ;

     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;

         for (Yuint i = ; i < stacks; i++)

         {

             nOffset = (i * ) * indexStriding;

             lineIndexPtr = (YsLineIndex16*)(indexPtr + nOffset);

             lineIndexPtr->index0 = i * ;

             lineIndexPtr->index1 = i *  + ;

             nOffset += indexStriding;

             lineIndexPtr = (YsLineIndex16*)(indexPtr + nOffset);

             lineIndexPtr->index0 = i *  + ;

             lineIndexPtr->index1 = i * ;

             nOffset += indexStriding;

             lineIndexPtr = (YsLineIndex16*)(indexPtr + nOffset);

             lineIndexPtr->index0 = i *  + ;

             lineIndexPtr->index1 = i *  + ;

         }

         nOffset = (stacks * ) * indexStriding;

         lineIndexPtr = (YsLineIndex16*)(indexPtr + nOffset);

         lineIndexPtr->index0 = stacks * ;

         lineIndexPtr->index1 = stacks *  + ;

     }

     else

     {

         YsLineIndex32* lineIndexPtr = NULL;

         for (Yuint i = ; i < stacks; i++)

         {

             nOffset = (i * ) * indexStriding;

             lineIndexPtr = (YsLineIndex32*)(indexPtr + nOffset);

             lineIndexPtr->index0 = i * ;

             lineIndexPtr->index1 = i *  + ;

             nOffset += indexStriding;

             lineIndexPtr = (YsLineIndex32*)(indexPtr + nOffset);

             lineIndexPtr->index0 = i *  + ;

             lineIndexPtr->index1 = i * ;

             nOffset += indexStriding;

             lineIndexPtr = (YsLineIndex32*)(indexPtr + nOffset);

             lineIndexPtr->index0 = i *  + ;

             lineIndexPtr->index1 = i *  + ;

         }

         nOffset = (stacks * ) * indexStriding;

         lineIndexPtr = (YsLineIndex32*)(indexPtr + nOffset);

         lineIndexPtr->index0 = stacks * ;

         lineIndexPtr->index1 = stacks *  + ;

     }

     return true;

 }