Take the 2-minute tour ×
Game Development Stack Exchange is a question and answer site for professional and independent game developers. It's 100% free, no registration required.

In my game, I have a mesh with a vertex buffer and index buffer up and running. The vertex buffer stores a Vector3 for the position and a Vector2 for the UV coordinate for each vertex. The index buffer is a list of ushorts. It works well, but I want to be able to use 3 discrete texture coordinates per triangle.

I assume I have to create another vertex buffer, but how do I even use it?

Here is my vertex/index buffer creation code:

// vertices is a Vertex[]
// indices is a ushort[]
// VertexDefs stores the vertex size (sizeof(float) * 5)

// vertex data
numVertices = vertices.Length;
DataStream data = new DataStream(VertexDefs.size * numVertices, true, true);
data.WriteRange<Vertex>(vertices);
data.Position = 0;

// vertex buffer parameters
BufferDescription vbDesc = new BufferDescription()
{
    BindFlags = BindFlags.VertexBuffer,
    CpuAccessFlags = CpuAccessFlags.None,
    OptionFlags = ResourceOptionFlags.None,
    SizeInBytes = VertexDefs.size * numVertices,
    StructureByteStride = VertexDefs.size,
    Usage = ResourceUsage.Default
};

// create vertex buffer
vertexBuffer = new Buffer(Graphics.device, data, vbDesc);
vertexBufferBinding = new VertexBufferBinding(vertexBuffer, VertexDefs.size, 0);
data.Dispose();

// index data
numIndices = indices.Length;
data = new DataStream(sizeof(ushort) * numIndices, true, true);
data.WriteRange<ushort>(indices);
data.Position = 0;

// index buffer parameters
BufferDescription ibDesc = new BufferDescription()
{
    BindFlags = BindFlags.IndexBuffer,
    CpuAccessFlags = CpuAccessFlags.None,
    OptionFlags = ResourceOptionFlags.None,
    SizeInBytes = sizeof(ushort) * numIndices,
    StructureByteStride = sizeof(ushort),
    Usage = ResourceUsage.Default
};

// create index buffer
indexBuffer = new Buffer(Graphics.device, data, ibDesc);
data.Dispose();

Engine.Log(MessageType.Success, string.Format("Mesh created with {0} vertices and {1} indices", numVertices, numIndices));

And my drawing code:

// ShaderEffect, ShaderTechnique, and ShaderPass all store effect data
// e is of type ShaderEffect

// get the technique
ShaderTechnique t;
if(!e.techniques.TryGetValue(techniqueName, out t))
    return;

// effect variables
e.SetMatrix("worldView", worldView);
e.SetMatrix("projection", projection);
e.SetResource("diffuseMap", texture);
e.SetSampler("textureSampler", sampler);

// set per-mesh/technique settings
Graphics.context.InputAssembler.SetVertexBuffers(0, vertexBufferBinding);
Graphics.context.InputAssembler.SetIndexBuffer(indexBuffer, SlimDX.DXGI.Format.R16_UInt, 0);
Graphics.context.PixelShader.SetSampler(sampler, 0);

// render for each pass
foreach(ShaderPass p in t.passes)
{
    Graphics.context.InputAssembler.InputLayout = p.layout;
    p.pass.Apply(Graphics.context);
    Graphics.context.DrawIndexed(numIndices, 0, 0);
}

How can I do this?

share|improve this question
add comment

1 Answer

up vote 2 down vote accepted

You don't need a separate vertex buffer, you can just put additional vertices in the same buffer. Rather than re-using vertices where faces meet, create a duplicate and set it's normal and texture coords to match the face that it belongs to.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.