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Render methods

Started by Mari_p Dec 28, 2003 at 10:24 PM 3 replies 300+ views

Original Post

Dec 28, 2003 at 10:24 PM

Compare the following two methods:

for(DWORD i = 0; i < NumMaterials; i++)
			{
				device->SetMaterial(&Materials[i]);
				device->SetTexture(0, Textures[i]);
			
				device->DrawIndexedPrimitive( D3DPT_TRIANGLELIST,
											  0,
											  pAttribTable[i].VertexStart,
											  pAttribTable[i].VertexCount,
											  pAttribTable[i].FaceStart*3,
											  pAttribTable[i].FaceCount );
			}

and

for(DWORD i = 0; i < NumMaterials; i++)
			{
				device->SetMaterial(&Materials[i]);
				device->SetTexture(0, Textures[i]);
			
				mesh->DrawSubset(i);
			}

OK, since they are called the same number of times per frame, in this case, what is the difference between them? I rendered my scene using these two methods and I didn''t notice any difference of performance. Thanks for the help.

glassJAw

Dec 28, 2003 at 10:56 PM

What is in mesh->DrawSubset()?

Mari_p

Author

Mari_p

Dec 28, 2003 at 11:09 PM

...do you mean what is being rendered? A scenery composed of ~50 meshes, each one with ~1000 vertices and some textures.

[edited by - Mari_p on December 28, 2003 12:09:44 AM]

Fidelio66

Dec 29, 2003 at 4:05 AM

A D3DXMESH is just a class that holds an index buffer, vertex buffer and some other stuff. The performance would be the same since they probably do the same.

It might even be worthwhile to use meshes for everything instead of defining and using vertex buffer/index buffer combinations yourself. With a mesh you can use a number of very useful utility functions, like sorting triangles to optimize the cache of the video card, weldvertices to merge points that are the same, normalize to generate averaged normals automatically, an advanced technique to draw it using less triangles (progressive mesh) and easy load/save to/from .x files.

DrunkenHyena

Dec 29, 2003 at 10:11 AM

Most importantly, DrawSubset requires less typing, which is not only great for lazy programmers but it''s also less error prone.

Stay Casual,

Ken
Drunken Hyena

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