bool ReleaseGridsResource(Vertex_VCN **ppVertices, unsigned short **ppIndices)
{
if ( *ppVertices )
{
GutRelease16BytesAlignedMemory(*ppVertices);
*ppVertices = NULL;
}
if ( *ppIndices )
{
delete [] *ppIndices;
*ppIndices = NULL;
}
return true;
}
void sModelMaterial_OpenGL::operator delete[](void *p)
{
GutRelease16BytesAlignedMemory(p);
}
// `產生x_grids * y_grids個格子的棋盤格模型`
bool GenerateGrids(int x_grids, int y_grids, Vertex_VCN **ppVertices, int &num_vertices, unsigned short **ppIndices, int &num_indices, int &num_triangles)
{
const int triangles_per_row = x_grids * 2;
const int indices_per_row = triangles_per_row + 2;
num_vertices = (x_grids + 1) * (y_grids + 1);
Vertex_VCN *pVertices = (Vertex_VCN *) GutAllocate16BytesAlignedMemory(sizeof(Vertex_VCN)*num_vertices);
*ppVertices = pVertices;
if ( pVertices==NULL )
return false;
num_indices = indices_per_row * y_grids;
unsigned short *pIndices = new unsigned short[num_indices];
*ppIndices = pIndices;
if ( pIndices==NULL )
{
GutRelease16BytesAlignedMemory(pVertices);
return false;
}
//` 使用triangle strip時, 三角形數目永遠等於索引值數目減去2`
num_triangles = num_indices-2;
Vector4 vCorner(-0.5f, 0.5f, 0.0f, 1.0f);
Vector4 vStep(1.0f/float(x_grids), -1.0f/float(y_grids), 0.0f, 0.0f);
Vector4 vPosition = vCorner;
Vector4 vNormal(0.0f, 0.0f, 1.0f);
Vector4 vColor(1.0f, 1.0f, 1.0f, 1.0f);
int x,y;
int vertex_index = 0;
for ( y=0; y<=y_grids; y++)
{
vPosition[0] = vCorner[0];
for ( x=0; x<=x_grids; x++, vertex_index++)
{
pVertices[vertex_index].m_Position = vPosition;
pVertices[vertex_index].m_Normal = vNormal;
pVertices[vertex_index].m_Color = vColor;
vPosition[0] += vStep[0];
}
vPosition[1] += vStep[1];
}
const int vertices_per_row = x_grids + 1;
bool from_left_to_right = true;
int index_index = 0;
for ( y=0; y<y_grids; y++ )
{
if ( from_left_to_right )
{
// `在奇數列的時候, 三角形從左排到右.`
pIndices[index_index++] = y * vertices_per_row;
pIndices[index_index++] = y * vertices_per_row + vertices_per_row;
for ( x=0; x<x_grids; x++ )
{
vertex_index = y * vertices_per_row + x;
pIndices[index_index++] = vertex_index + 1;
pIndices[index_index++] = vertex_index + 1 + vertices_per_row;
}
}
else
{
// `在偶數列的時候, 三角形從右排到左.`
pIndices[index_index++] = y * vertices_per_row + x_grids;
pIndices[index_index++] = (y+1) * vertices_per_row + x_grids;
for ( x=x_grids; x>0; x-- )
{
vertex_index = y * vertices_per_row + x;
pIndices[index_index++] = vertex_index - 1;
pIndices[index_index++] = vertex_index - 1 + vertices_per_row;
}
}
from_left_to_right = !from_left_to_right;
}
return true;
}