Instanced drawing

animated_mesh.cc

	void animated_mesh::draw(animated_mesh& model, std::vector<instance_data> const& instances, D3DXMATRIX view, D3DXMATRIX projection)
	{
		auto hr = noisy_hresult();

		unsigned stride[] = { sizeof(vertex_type_a), sizeof(vertex_type_b), sizeof(instance_data) };
		unsigned offset[] = { 0, 0, 0 };

		CComPtr<ID3D11DeviceContext> ctx = model.ctx;
		CComPtr<ID3D11Device> device;
		ctx->GetDevice(&device);

		auto instance_vb = rendering::make_vertex_buffer(device, instances);
		auto& geom = model.geometry;
		auto& shaders = model.shaders;
		
		for (size_t i = 0; i < geom.vertex_buffers.size(); ++i)
		{
			ctx->IASetVertexBuffers(i, 1, &geom.vertex_buffers[i].buffer.p, stride + i, offset + i);
		}
				
		if (geom.index_buffer)
		{
			ctx->IASetIndexBuffer(geom.index_buffer, DXGI_FORMAT_R32_UINT, 0);
		}

		// set third buffer to the per-instance one
		ctx->IASetVertexBuffers(2, 1, &instance_vb.buffer.p, stride + 2, offset + 2);
		ctx->IASetPrimitiveTopology(D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST);

		D3D11_MAPPED_SUBRESOURCE map_result;
		hr = ctx->Map(shaders.matrix_buffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &map_result);

		auto p = static_cast<rendering::matrix_buffer_type*>(map_result.pData);
		D3DXMatrixIdentity(&p->world);
		D3DXMatrixTranspose(&p->view, &view);
		D3DXMatrixTranspose(&p->projection, &projection);
		ctx->Unmap(shaders.matrix_buffer, 0);

		unsigned buffer_index = 0;
		ctx->VSSetConstantBuffers(buffer_index, 1, &shaders.matrix_buffer.p);

		ctx->IASetInputLayout(shaders.layout);
		ctx->VSSetShader(shaders.vs, NULL, 0);
		ctx->PSSetShader(shaders.ps, NULL, 0);

		if (geom.index_buffer)
		{
			ctx->DrawIndexedInstanced(geom.n_indices, instances.size(), 0, 0, 0);
		}
		else
		{
			ctx->DrawInstanced(geom.n_vertices, instances.size(), 0, 0);
		}
	}