1 bool                        YfBuildSpiralStairsVertices
 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     Yuint numVertices  = 2 + stacks * 4;
19     //Yuint numTriangles = stacks * 8;
20
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 = -height;
29     }
30     else if (originPose == YE_ORIGIN_POSE_CENTER)
31     {
32         originOffsetY = -height * 0.5f;
33     }
34
35     Yreal fStepTexcoord = 1.0f / (stacks - 1);
36     Yreal fStepHeight = height / stacks;
37     Yreal fStepAngle = YD_REAL_TWAIN_PI / slices;
38
39     Yreal angleXZ;
40     Yreal posX, posZ;
41     for (Yuint i = 0; i <= stacks; i++)
42     {
43         angleXZ = i * fStepAngle;
44         posX = yf_sin(angleXZ);
45         posZ = yf_cos(angleXZ);
46
47         nOffset = i * 4 * vertexStriding;
48         curVertexPtr = (YsVector3*)(vertexPtr + nOffset);
49         curVertexPtr->x = radius * posX;
50         curVertexPtr->y = i * fStepHeight + originOffsetY;
51         curVertexPtr->z = radius * posZ;
52
53         nOffset += vertexStriding;
54         curVertexPtr = (YsVector3*)(vertexPtr + nOffset);
55         curVertexPtr->x = assistRadius * posX;
56         curVertexPtr->y = i * fStepHeight + originOffsetY;
57         curVertexPtr->z = assistRadius * posZ;
58
59         if (i == stacks)
60         {
61             continue;
62         }
63
64         nOffset += vertexStriding;
65         curVertexPtr = (YsVector3*)(vertexPtr + nOffset);
66         curVertexPtr->x = radius * posX;
67         curVertexPtr->y = (i+1) * fStepHeight + originOffsetY;
68         curVertexPtr->z = radius * posZ;
69
70         nOffset += vertexStriding;
71         curVertexPtr = (YsVector3*)(vertexPtr + nOffset);
72         curVertexPtr->x = assistRadius * posX;
73         curVertexPtr->y = (i+1) * fStepHeight + originOffsetY;
74         curVertexPtr->z = assistRadius * posZ;
75     }
76
77     return true;
78 }

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