[16] 螺旋面(Spire)图形的生成算法

顶点数据的生成

 1 bool                        YfBuildSpireVertices
 2 (
 3     Yreal                   radius, 
 4     Yreal                   assistRadius, 
 5     Yreal                   height, 
 6     Yuint                   slices,
 7     Yuint                   stacks, 
 8     YeOriginPose            originPose,
 9     Yuint                   vertexStriding, 
10     Yuint                   vertexPos,
11     void*                   pVerticesBuffer
12 )
13 {
14     if (stacks < 1 || slices < 3 || !pVerticesBuffer)
15     {
16         return false;
17     }
18 
19     Yuint numVertices  = 2 + stacks * 2;
20     //Yuint numTriangles = stacks * 2;
21 
22     char* vertexPtr = (char*)pVerticesBuffer + vertexPos;
23     YsVector3* curVertexPtr = NULL;
24     Yuint nOffset = 0;
25 
26     Yreal originOffsetY = 0.0f;
27     if (originPose == YE_ORIGIN_POSE_TOP)
28     {
29         originOffsetY = -height;
30     }
31     else if (originPose == YE_ORIGIN_POSE_CENTER)
32     {
33         originOffsetY = -height * 0.5f;
34     }
35 
36     Yreal fAngle = YD_REAL_TWAIN_PI / slices;
37 
38     Yreal angleXZ;
39     Yreal posX, posZ;        
40     for (Yuint i = 0; i <= stacks; i++)
41     {
42         angleXZ = i * fAngle;
43         posX = yf_sin(angleXZ);
44         posZ = yf_cos(angleXZ);
45         nOffset = i * 2 * vertexStriding; 
46 
47         curVertexPtr = (YsVector3*)(vertexPtr + nOffset);
48         curVertexPtr->x = assistRadius * posX;
49         curVertexPtr->y = height * i * 1.0f / stacks + originOffsetY;
50         curVertexPtr->z = assistRadius * posZ;
51     
52         nOffset += vertexStriding;  
53 
54         curVertexPtr = (YsVector3*)(vertexPtr + nOffset);
55         curVertexPtr->x = radius * posX;
56         curVertexPtr->y = height * i * 1.0f / stacks + originOffsetY;
57         curVertexPtr->z = radius * posZ;
58     }
59 
60     return true;
61 }

三角形索引数据的生成

 1 bool                        YfBuildSpireTriIndices
 2 (
 3     Yuint                   stacks, 
 4     YeIndexType             indexType,
 5     Yuint                   indexStriding,  
 6     Yuint                   indexPos, 
 7     void*                   pTriIndicesBuffer
 8 )
 9 {
10     if (stacks < 3 || !pTriIndicesBuffer)
11     {
12         return false;
13     }
14 
15     Yuint numVertices  = 2 + stacks * 2;
16     Yuint numTriangles = stacks * 2;
17     if (indexType == YE_INDEX_16_BIT && 
18         numVertices > YD_MAX_UNSIGNED_INT16)
19     {
20         return false;
21     }
22 
23     // 索引赋值
24     char* indexPtr = (char*)pTriIndicesBuffer + indexPos;
25     Yuint nOffset = 0;
26     if (indexType == YE_INDEX_16_BIT)
27     {
28         YsTriIndex16* triIndexPtr = NULL;
29         for (Yuint i = 0; i < stacks; i++)
30         {
31             nOffset = 2 * i * indexStriding;
32             triIndexPtr = (YsTriIndex16*)(indexPtr + nOffset);
33             triIndexPtr->index0 = i*2;
34             triIndexPtr->index1 = i*2 + 1;
35             triIndexPtr->index2 = i*2 + 3;
36 
37             nOffset += indexStriding;
38             triIndexPtr = (YsTriIndex16*)(indexPtr + nOffset);
39             triIndexPtr->index0 = i*2;
40             triIndexPtr->index1 = i*2 + 3;
41             triIndexPtr->index2 = i*2 + 2;
42         }
43     }
44     else
45     {
46         YsTriIndex32* triIndexPtr = NULL;
47         for (Yuint i = 0; i < stacks; i++)
48         {
49             nOffset = 2 * i * indexStriding;
50             triIndexPtr = (YsTriIndex32*)(indexPtr + nOffset);
51             triIndexPtr->index0 = i*2;
52             triIndexPtr->index1 = i*2 + 1;
53             triIndexPtr->index2 = i*2 + 3;
54 
55             nOffset += indexStriding;
56             triIndexPtr = (YsTriIndex32*)(indexPtr + nOffset);
57             triIndexPtr->index0 = i*2;
58             triIndexPtr->index1 = i*2 + 3;
59             triIndexPtr->index2 = i*2 + 2;
60         }
61     }
62 
63     return true;
64 }

线框索引数据的生成

 1 bool                        YfBuildSpireWireIndices
 2 (
 3     Yuint                   stacks, 
 4     YeIndexType             indexType,
 5     Yuint                   indexStriding, 
 6     Yuint                   indexPos, 
 7     void*                   pWireIndicesBuffer
 8 )
 9 {
10     if (stacks < 3 || !pWireIndicesBuffer)
11     {
12         return false;
13     }
14 
15     Yuint numVertices = 2 + stacks * 2;
16     Yuint numLines    = 1 + stacks * 3;
17     if (indexType == YE_INDEX_16_BIT && 
18         numVertices > YD_MAX_UNSIGNED_INT16)
19     {
20         return false;
21     }
22 
23     // 索引赋值
24     char* indexPtr = (char*)pWireIndicesBuffer + indexPos;
25     Yuint nOffset = 0;
26     if (indexType == YE_INDEX_16_BIT)
27     {
28         YsLineIndex16* lineIndexPtr = NULL;
29         for (Yuint i = 0; i < stacks; i++)
30         {
31             nOffset = (i * 3) * indexStriding;
32             lineIndexPtr = (YsLineIndex16*)(indexPtr + nOffset);
33             lineIndexPtr->index0 = i * 2;
34             lineIndexPtr->index1 = i * 2 + 1;
35 
36             nOffset += indexStriding;
37             lineIndexPtr = (YsLineIndex16*)(indexPtr + nOffset);
38             lineIndexPtr->index0 = i * 2 + 2;
39             lineIndexPtr->index1 = i * 2;
40 
41             nOffset += indexStriding;
42             lineIndexPtr = (YsLineIndex16*)(indexPtr + nOffset);
43             lineIndexPtr->index0 = i * 2 + 3;
44             lineIndexPtr->index1 = i * 2 + 1;
45         }
46 
47         nOffset = (stacks * 3) * indexStriding;
48         lineIndexPtr = (YsLineIndex16*)(indexPtr + nOffset);
49         lineIndexPtr->index0 = stacks * 2;
50         lineIndexPtr->index1 = stacks * 2 + 1;
51     }
52     else
53     {
54         YsLineIndex32* lineIndexPtr = NULL;
55         for (Yuint i = 0; i < stacks; i++)
56         {
57             nOffset = (i * 3) * indexStriding;
58             lineIndexPtr = (YsLineIndex32*)(indexPtr + nOffset);
59             lineIndexPtr->index0 = i * 2;
60             lineIndexPtr->index1 = i * 2 + 1;
61 
62             nOffset += indexStriding;
63             lineIndexPtr = (YsLineIndex32*)(indexPtr + nOffset);
64             lineIndexPtr->index0 = i * 2 + 2;
65             lineIndexPtr->index1 = i * 2;
66 
67             nOffset += indexStriding;
68             lineIndexPtr = (YsLineIndex32*)(indexPtr + nOffset);
69             lineIndexPtr->index0 = i * 2 + 3;
70             lineIndexPtr->index1 = i * 2 + 1;
71         }
72 
73         nOffset = (stacks * 3) * indexStriding;
74         lineIndexPtr = (YsLineIndex32*)(indexPtr + nOffset);
75         lineIndexPtr->index0 = stacks * 2;
76         lineIndexPtr->index1 = stacks * 2 + 1;
77     }
78 
79     return true;
80 }

posted on 2013-11-09 08:56 叶飞影阅读(1047) 评论(0) 编辑收藏举报