[2] 立方体(Box)图形的生成算法
顶点数据的生成
1 bool YfBuildBoxVertices 2 ( 3 Yreal extentX, 4 Yreal extentY, 5 Yreal extentZ, 6 YeOriginPose originPose, 7 Yuint vertexStriding, 8 Yuint vertexPos, 9 void* pVerticesBuffer 10 ) 11 { 12 if (!pVerticesBuffer) 13 { 14 return false; 15 } 16 17 Yuint numVertices = 8; 18 19 // 顶点赋值 20 char* vertexPtr = (char*)pVerticesBuffer + vertexPos; 21 22 YsVector3* curVertexPtr = NULL; 23 YsVector3* curNormalPtr = NULL; 24 YsVector2* curTexcoordPtr = NULL; 25 26 Yuint nOffset = 0; 27 28 YsVector3 vOriginOffset(-extentX / 2, -extentY / 2, -extentZ / 2); 29 if (originPose == YE_ORIGIN_POSE_TOP) 30 { 31 vOriginOffset.y = -extentY; 32 } 33 else if (originPose == YE_ORIGIN_POSE_BOTTOM) 34 { 35 vOriginOffset.y = 0.0f; 36 } 37 38 for (Yuint k = 0; k < 2; k++) 39 { 40 for (Yuint j = 0; j < 2; j++) 41 { 42 for (Yuint i = 0; i < 2; i++) 43 { 44 nOffset = (k*4 + j*2 + i) * vertexStriding; 45 curVertexPtr = (YsVector3*)(vertexPtr + nOffset); 46 curVertexPtr->x = extentX*i + vOriginOffset.x; 47 curVertexPtr->z = extentZ*j + vOriginOffset.z; 48 curVertexPtr->y = extentY*k + vOriginOffset.y; 49 } 50 } 51 } 52 53 return true; 54 }
三角形索引数据的生成
1 bool YfBuildBoxTriIndices 2 ( 3 YeIndexType indexType, 4 Yuint indexStriding, 5 Yuint indexPos, 6 void* pTriIndicesBuffer 7 ) 8 { 9 if (!pTriIndicesBuffer) 10 { 11 return false; 12 } 13 14 char* indexPtr = (char*)pTriIndicesBuffer + indexPos; 15 if (indexType == YE_INDEX_16_BIT) 16 { 17 YsTriIndex16* triIndexPtr[12]; 18 for (Yuint i = 0; i < 12; i++) 19 { 20 triIndexPtr[i] = (YsTriIndex16*)(indexPtr + i * indexStriding); 21 } 22 23 // bottom 24 triIndexPtr[0]->index0 = 0; triIndexPtr[0]->index1 = 1; triIndexPtr[0]->index2 = 3; 25 triIndexPtr[1]->index0 = 0; triIndexPtr[1]->index1 = 3; triIndexPtr[1]->index2 = 2; 26 27 // top 28 triIndexPtr[10]->index0= 4; triIndexPtr[10]->index1= 6; triIndexPtr[10]->index2= 7; 29 triIndexPtr[11]->index0= 4; triIndexPtr[11]->index1= 7; triIndexPtr[11]->index2= 5; 30 31 // front side 32 triIndexPtr[2]->index0 = 0; triIndexPtr[2]->index1 = 4; triIndexPtr[2]->index2 = 5; 33 triIndexPtr[3]->index0 = 0; triIndexPtr[3]->index1 = 5; triIndexPtr[3]->index2 = 1; 34 35 // back side 36 triIndexPtr[4]->index0 = 2; triIndexPtr[4]->index1 = 3; triIndexPtr[4]->index2 = 7; 37 triIndexPtr[5]->index0 = 2; triIndexPtr[5]->index1 = 7; triIndexPtr[5]->index2 = 6; 38 39 // right side 40 triIndexPtr[6]->index0 = 1; triIndexPtr[6]->index1 = 5; triIndexPtr[6]->index2 = 7; 41 triIndexPtr[7]->index0 = 1; triIndexPtr[7]->index1 = 7; triIndexPtr[7]->index2 = 3; 42 43 // left side 44 triIndexPtr[8]->index0 = 0; triIndexPtr[8]->index1 = 2; triIndexPtr[8]->index2 = 6; 45 triIndexPtr[9]->index0 = 0; triIndexPtr[9]->index1 = 6; triIndexPtr[9]->index2 = 4; 46 } 47 else 48 { 49 YsTriIndex32* triIndexPtr[12]; 50 for (Yuint i = 0; i < 12; i++) 51 { 52 triIndexPtr[i] = (YsTriIndex32*)(indexPtr + i * indexStriding); 53 } 54 55 // bottom 56 triIndexPtr[0]->index0 = 0; triIndexPtr[0]->index1 = 1; triIndexPtr[0]->index2 = 3; 57 triIndexPtr[1]->index0 = 0; triIndexPtr[1]->index1 = 3; triIndexPtr[1]->index2 = 2; 58 59 // top 60 triIndexPtr[10]->index0= 4; triIndexPtr[10]->index1= 6; triIndexPtr[10]->index2= 7; 61 triIndexPtr[11]->index0= 4; triIndexPtr[11]->index1= 7; triIndexPtr[11]->index2= 5; 62 63 // front side 64 triIndexPtr[2]->index0 = 0; triIndexPtr[2]->index1 = 4; triIndexPtr[2]->index2 = 5; 65 triIndexPtr[3]->index0 = 0; triIndexPtr[3]->index1 = 5; triIndexPtr[3]->index2 = 1; 66 67 // back side 68 triIndexPtr[4]->index0 = 2; triIndexPtr[4]->index1 = 3; triIndexPtr[4]->index2 = 7; 69 triIndexPtr[5]->index0 = 2; triIndexPtr[5]->index1 = 7; triIndexPtr[5]->index2 = 6; 70 71 // right side 72 triIndexPtr[6]->index0 = 1; triIndexPtr[6]->index1 = 5; triIndexPtr[6]->index2 = 7; 73 triIndexPtr[7]->index0 = 1; triIndexPtr[7]->index1 = 7; triIndexPtr[7]->index2 = 3; 74 75 // left side 76 triIndexPtr[8]->index0 = 0; triIndexPtr[8]->index1 = 2; triIndexPtr[8]->index2 = 6; 77 triIndexPtr[9]->index0 = 0; triIndexPtr[9]->index1 = 6; triIndexPtr[9]->index2 = 4; 78 } 79 80 return true; 81 }
线框索引数据的生成
1 bool YfBuildBoxWireIndices 2 ( 3 YeIndexType indexType, 4 Yuint indexStriding, 5 Yuint indexPos, 6 void* pWireIndicesBuffer 7 ) 8 { 9 if (!pWireIndicesBuffer) 10 { 11 return false; 12 } 13 14 char* indexPtr = (char*)pWireIndicesBuffer + indexPos; 15 if (indexType == YE_INDEX_16_BIT) 16 { 17 YsLineIndex16* lineIndexPtr[12]; 18 for (Yuint i = 0; i < 12; i++) 19 { 20 lineIndexPtr[i] = (YsLineIndex16*)(indexPtr + i * indexStriding); 21 } 22 23 // bottom 24 lineIndexPtr[0]->index0 = 0; lineIndexPtr[0]->index1 = 1; 25 lineIndexPtr[1]->index0 = 0; lineIndexPtr[1]->index1 = 2; 26 lineIndexPtr[2]->index0 = 3; lineIndexPtr[2]->index1 = 1; 27 lineIndexPtr[3]->index0 = 3; lineIndexPtr[3]->index1 = 2; 28 29 // center 30 lineIndexPtr[4]->index0 = 0; lineIndexPtr[4]->index1 = 4; 31 lineIndexPtr[5]->index0 = 1; lineIndexPtr[5]->index1 = 5; 32 lineIndexPtr[6]->index0 = 2; lineIndexPtr[6]->index1 = 6; 33 lineIndexPtr[7]->index0 = 3; lineIndexPtr[7]->index1 = 7; 34 35 // top 36 lineIndexPtr[8]->index0 = 4; lineIndexPtr[8]->index1 = 5; 37 lineIndexPtr[9]->index0 = 4; lineIndexPtr[9]->index1 = 6; 38 lineIndexPtr[10]->index0= 7; lineIndexPtr[10]->index1= 5; 39 lineIndexPtr[11]->index0= 7; lineIndexPtr[11]->index1= 6; 40 } 41 else 42 { 43 YsLineIndex32* lineIndexPtr[12]; 44 for (Yuint i = 0; i < 12; i++) 45 { 46 lineIndexPtr[i] = (YsLineIndex32*)(indexPtr + i * indexStriding); 47 } 48 49 // bottom 50 lineIndexPtr[0]->index0 = 0; lineIndexPtr[0]->index1 = 1; 51 lineIndexPtr[1]->index0 = 0; lineIndexPtr[1]->index1 = 2; 52 lineIndexPtr[2]->index0 = 3; lineIndexPtr[2]->index1 = 1; 53 lineIndexPtr[3]->index0 = 3; lineIndexPtr[3]->index1 = 2; 54 55 // center 56 lineIndexPtr[4]->index0 = 0; lineIndexPtr[4]->index1 = 4; 57 lineIndexPtr[5]->index0 = 1; lineIndexPtr[5]->index1 = 5; 58 lineIndexPtr[6]->index0 = 2; lineIndexPtr[6]->index1 = 6; 59 lineIndexPtr[7]->index0 = 3; lineIndexPtr[7]->index1 = 7; 60 61 // top 62 lineIndexPtr[8]->index0 = 4; lineIndexPtr[8]->index1 = 5; 63 lineIndexPtr[9]->index0 = 4; lineIndexPtr[9]->index1 = 6; 64 lineIndexPtr[10]->index0= 7; lineIndexPtr[10]->index1= 5; 65 lineIndexPtr[11]->index0= 7; lineIndexPtr[11]->index1= 6; 66 } 67 68 return true; 69 }
