[20] 鼓状物(Drum)图形的生成算法

1 bool YfBuildDrumVertices  2 (  3  Yreal radius,  4  Yreal assistRadius,  5  Yuint slices,  6  Yuint stacks,  7  YeOriginPose originPose,  8  Yuint vertexStriding,  9  Yuint vertexPos, 10     void* pVerticesBuffer 11 ) 12 { 13     if (slices < 2 || stacks < 3 || !pVerticesBuffer) 14  { 15         return false; 16  } 17
18     Yuint numVertices  = slices * stacks + 2; 19
20     // 顶点赋值
21     char* vertexPtr   = (char*)pVerticesBuffer + vertexPos; 22     YsVector3* curVertexPtr   = NULL; 23     Yuint nOffset = 0; 24
25     Yreal originOffsetY = 0.0f; 26     if (originPose == YE_ORIGIN_POSE_TOP) 27  { 28         originOffsetY = -radius; 29  } 30     else if (originPose == YE_ORIGIN_POSE_BOTTOM) 31  { 32         originOffsetY = radius; 33  } 34
35     Yreal* pSinList = YD_NEW_ARRAY(Yreal, slices); 36     Yreal* pCosList = YD_NEW_ARRAY(Yreal, slices); 37  Yreal angleXZ; 38     for (Yuint j = 0; j < slices; j++) 39  { 40         angleXZ = YD_REAL_TWAIN_PI * j / slices; 41         pSinList[j] = yf_sin(angleXZ); 42         pCosList[j] = yf_cos(angleXZ); 43  } 44
45     // 赋值
46  { 47         // 第一个顶点
48  { 49             nOffset = 0; 50             curVertexPtr = (YsVector3*)(vertexPtr + nOffset); 51             curVertexPtr->x = 0.0f; 52             curVertexPtr->y = radius + originOffsetY; 53             curVertexPtr->z = 0.0f; 54  } 55
56         // 最后一个顶点
57  { 58             nOffset = (numVertices - 1) * vertexStriding; 59             curVertexPtr = (YsVector3*)(vertexPtr + nOffset); 60             curVertexPtr->x = 0.0f; 61             curVertexPtr->y = -radius + originOffsetY; 62             curVertexPtr->z = 0.0f; 63  } 64
65         for (Yuint i = 0; i < stacks; i++) 66  { 67             Yreal angleY = YD_REAL_PI * i / (stacks - 1); 68             Yreal posY = radius * yf_cos(angleY); 69             Yreal radiusXZ = assistRadius + radius * yf_sin(angleY); 70  Yreal posX, posZ; 71
72             for (Yuint j = 0; j < slices; j++) 73  { 74                 posX = radiusXZ * pSinList[j]; 75                 posZ = radiusXZ * pCosList[j]; 76                 nOffset = (i * slices + j + 1) * vertexStriding; 77                 curVertexPtr = (YsVector3*)(vertexPtr + nOffset); 78                 curVertexPtr->x = posX; 79                 curVertexPtr->y = posY + originOffsetY; 80                 curVertexPtr->z = posZ; 81  } 82  } 83  } 84
85  YD_SAFE_DELETE_ARRAY(pSinList); 86  YD_SAFE_DELETE_ARRAY(pCosList); 87
88     return true; 89 }

1 bool YfBuildDrumTriIndices  2 (  3  Yuint slices,  4  Yuint stacks,  5  YeIndexType indexType,  6  Yuint indexStriding,  7  Yuint indexPos,  8     void* pTriIndicesBuffer  9 ) 10 { 11     return YfBuildSphereTriIndices( 12  slices, 13         stacks + 2, 14  indexType, 15  indexStriding, 16  indexPos, 17  pTriIndicesBuffer); 18 } 19
20 bool YfBuildDrumWireIndices 21 ( 22  Yuint slices, 23  Yuint stacks, 24  YeIndexType indexType, 25  Yuint indexStriding, 26  Yuint indexPos, 27     void* pWireIndicesBuffer 28 ) 29 { 30     return YfBuildSphereWireIndices( 31  slices, 32         stacks + 2, 33  indexType, 34  indexStriding, 35  indexPos, 36  pWireIndicesBuffer); 37 }