有很多创建MDLMesh的示例,可以使用其中一个工厂参数方法,例如创建一个立方体:
[MDLMesh newBoxWithDimensions:...
使用其中最简单的方式,对于一个“平面”(矩形),我生成了一个顶点数量最少的1x1矩形:
MDLMesh *mdlMesh = [MDLMesh newPlaneWithDimensions:(vector_float2){1.0, 1.0}
segments:(vector_uint2){1, 1}
geometryType:MDLGeometryTypeTriangles
allocator:metalAllocator]
我随后使用Xcode调试器来研究生成的MDLMesh的情况,以指导我创建一个更简单的对象——编程平等三角形。
以下代码适用于我。我相信比我更懂Metal的人可以提供更好的解决方案。但这将希望让你朝着正确的方向开始…
因此,在出现新的工厂参数化方法之前,
[MDLMesh newEquilateralTriangleWithEdgeLength:...
下面的代码似乎能够解决问题...
static const float equilateralTriangleVertexData[] =
{
0.000000, 0.577350, 0.0,
-0.500000, -0.288675, 0.0,
0.500000, -0.288675, 0.0,
};
static const vector_float3 equilateralTriangleVertexNormalsData[] =
{
{ 0.0, 0.0, 1.0 },
{ 0.0, 0.0, 1.0 },
{ 0.0, 0.0, 1.0 },
};
static const vector_float2 equilateralTriangleVertexTexData[] =
{
{ 0.50, 1.00 },
{ 0.00, 0.00 },
{ 1.00, 0.00 },
};
int numVertices = 3;
int lenBufferForVertices_position = sizeof(equilateralTriangleVertexData);
int lenBufferForVertices_normal = numVertices * sizeof(vector_float3);
int lenBufferForVertices_textureCoordinate = numVertices * sizeof(vector_float2);
MTKMeshBuffer *mtkMeshBufferForVertices_position = (MTKMeshBuffer *)[metalAllocator newBuffer:lenBufferForVertices_position type:MDLMeshBufferTypeVertex];
MTKMeshBuffer *mtkMeshBufferForVertices_normal = (MTKMeshBuffer *)[metalAllocator newBuffer:lenBufferForVertices_normal type:MDLMeshBufferTypeVertex];
MTKMeshBuffer *mtkMeshBufferForVertices_textureCoordinate = (MTKMeshBuffer *)[metalAllocator newBuffer:lenBufferForVertices_textureCoordinate type:MDLMeshBufferTypeVertex];
NSData *nsData_position = [NSData dataWithBytes:equilateralTriangleVertexData length:lenBufferForVertices_position];
NSData *nsData_normal = [NSData dataWithBytes:equilateralTriangleVertexNormalsData length:lenBufferForVertices_normal];
NSData *nsData_textureCoordinate = [NSData dataWithBytes:equilateralTriangleVertexTexData length:lenBufferForVertices_textureCoordinate];
[mtkMeshBufferForVertices_position fillData:nsData_position offset:0];
[mtkMeshBufferForVertices_normal fillData:nsData_normal offset:0];
[mtkMeshBufferForVertices_textureCoordinate fillData:nsData_textureCoordinate offset:0];
NSArray <id<MDLMeshBuffer>> *arrayOfMeshBuffers = [NSArray arrayWithObjects:mtkMeshBufferForVertices_position, mtkMeshBufferForVertices_normal, mtkMeshBufferForVertices_textureCoordinate, nil];
static uint16_t indices[] =
{
0, 1, 2,
};
int numIndices = 3;
int lenBufferForIndices = numIndices * sizeof(uint16_t);
MTKMeshBuffer *mtkMeshBufferForIndices = (MTKMeshBuffer *)[metalAllocator newBuffer:lenBufferForIndices type:MDLMeshBufferTypeIndex];
NSData *nsData_indices = [NSData dataWithBytes:indices length:lenBufferForIndices];
[mtkMeshBufferForIndices fillData:nsData_indices offset:0];
MDLScatteringFunction *scatteringFunction = [MDLPhysicallyPlausibleScatteringFunction new];
MDLMaterial *material = [[MDLMaterial alloc] initWithName:@"plausibleMaterial" scatteringFunction:scatteringFunction];
MDLSubmesh *submesh = [[MDLSubmesh alloc] initWithName:@"summess"
indexBuffer:mtkMeshBufferForIndices
indexCount:numIndices
indexType:MDLIndexBitDepthUInt16
geometryType:MDLGeometryTypeTriangles
material:material];
NSArray <MDLSubmesh *> *arrayOfSubmeshes = [NSArray arrayWithObjects:submesh, nil];
MDLMesh *mdlMesh = [[MDLMesh alloc] initWithVertexBuffers:arrayOfMeshBuffers
vertexCount:numVertices
descriptor:mdlVertexDescriptor
submeshes:arrayOfSubmeshes];