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trellis/models/structured_latent_flow.py

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+from typing import *
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+import numpy as np
+from ..modules.utils import zero_module, convert_module_to_f16, convert_module_to_f32
+from ..modules.transformer import AbsolutePositionEmbedder
+from ..modules.norm import LayerNorm32
+from ..modules import sparse as sp
+from ..modules.sparse.transformer import ModulatedSparseTransformerCrossBlock
+from .sparse_structure_flow import TimestepEmbedder
+from .sparse_elastic_mixin import SparseTransformerElasticMixin
+
+
+class SparseResBlock3d(nn.Module):
+    def __init__(
+        self,
+        channels: int,
+        emb_channels: int,
+        out_channels: Optional[int] = None,
+        downsample: bool = False,
+        upsample: bool = False,
+    ):
+        super().__init__()
+        self.channels = channels
+        self.emb_channels = emb_channels
+        self.out_channels = out_channels or channels
+        self.downsample = downsample
+        self.upsample = upsample
+        
+        assert not (downsample and upsample), "Cannot downsample and upsample at the same time"
+
+        self.norm1 = LayerNorm32(channels, elementwise_affine=True, eps=1e-6)
+        self.norm2 = LayerNorm32(self.out_channels, elementwise_affine=False, eps=1e-6)
+        self.conv1 = sp.SparseConv3d(channels, self.out_channels, 3)
+        self.conv2 = zero_module(sp.SparseConv3d(self.out_channels, self.out_channels, 3))
+        self.emb_layers = nn.Sequential(
+            nn.SiLU(),
+            nn.Linear(emb_channels, 2 * self.out_channels, bias=True),
+        )
+        self.skip_connection = sp.SparseLinear(channels, self.out_channels) if channels != self.out_channels else nn.Identity()
+        self.updown = None
+        if self.downsample:
+            self.updown = sp.SparseDownsample(2)
+        elif self.upsample:
+            self.updown = sp.SparseUpsample(2)
+
+    def _updown(self, x: sp.SparseTensor) -> sp.SparseTensor:
+        if self.updown is not None:
+            x = self.updown(x)
+        return x
+
+    def forward(self, x: sp.SparseTensor, emb: torch.Tensor) -> sp.SparseTensor:
+        emb_out = self.emb_layers(emb).type(x.dtype)
+        scale, shift = torch.chunk(emb_out, 2, dim=1)
+
+        x = self._updown(x)
+        h = x.replace(self.norm1(x.feats))
+        h = h.replace(F.silu(h.feats))
+        h = self.conv1(h)
+        h = h.replace(self.norm2(h.feats)) * (1 + scale) + shift
+        h = h.replace(F.silu(h.feats))
+        h = self.conv2(h)
+        h = h + self.skip_connection(x)
+
+        return h
+    
+
+class SLatFlowModel(nn.Module):
+    def __init__(
+        self,
+        resolution: int,
+        in_channels: int,
+        model_channels: int,
+        cond_channels: int,
+        out_channels: int,
+        num_blocks: int,
+        num_heads: Optional[int] = None,
+        num_head_channels: Optional[int] = 64,
+        mlp_ratio: float = 4,
+        patch_size: int = 2,
+        num_io_res_blocks: int = 2,
+        io_block_channels: List[int] = None,
+        pe_mode: Literal["ape", "rope"] = "ape",
+        use_fp16: bool = False,
+        use_checkpoint: bool = False,
+        use_skip_connection: bool = True,
+        share_mod: bool = False,
+        qk_rms_norm: bool = False,
+        qk_rms_norm_cross: bool = False,
+    ):
+        super().__init__()
+        self.resolution = resolution
+        self.in_channels = in_channels
+        self.model_channels = model_channels
+        self.cond_channels = cond_channels
+        self.out_channels = out_channels
+        self.num_blocks = num_blocks
+        self.num_heads = num_heads or model_channels // num_head_channels
+        self.mlp_ratio = mlp_ratio
+        self.patch_size = patch_size
+        self.num_io_res_blocks = num_io_res_blocks
+        self.io_block_channels = io_block_channels
+        self.pe_mode = pe_mode
+        self.use_fp16 = use_fp16
+        self.use_checkpoint = use_checkpoint
+        self.use_skip_connection = use_skip_connection
+        self.share_mod = share_mod
+        self.qk_rms_norm = qk_rms_norm
+        self.qk_rms_norm_cross = qk_rms_norm_cross
+        self.dtype = torch.float16 if use_fp16 else torch.float32
+
+        if self.io_block_channels is not None:
+            assert int(np.log2(patch_size)) == np.log2(patch_size), "Patch size must be a power of 2"
+            assert np.log2(patch_size) == len(io_block_channels), "Number of IO ResBlocks must match the number of stages"
+
+        self.t_embedder = TimestepEmbedder(model_channels)
+        if share_mod:
+            self.adaLN_modulation = nn.Sequential(
+                nn.SiLU(),
+                nn.Linear(model_channels, 6 * model_channels, bias=True)
+            )
+
+        if pe_mode == "ape":
+            self.pos_embedder = AbsolutePositionEmbedder(model_channels)
+
+        self.input_layer = sp.SparseLinear(in_channels, model_channels if io_block_channels is None else io_block_channels[0])
+        
+        self.input_blocks = nn.ModuleList([])
+        if io_block_channels is not None:
+            for chs, next_chs in zip(io_block_channels, io_block_channels[1:] + [model_channels]):
+                self.input_blocks.extend([
+                    SparseResBlock3d(
+                        chs,
+                        model_channels,
+                        out_channels=chs,
+                    )
+                    for _ in range(num_io_res_blocks-1)
+                ])
+                self.input_blocks.append(
+                    SparseResBlock3d(
+                        chs,
+                        model_channels,
+                        out_channels=next_chs,
+                        downsample=True,
+                    )
+                )
+            
+        self.blocks = nn.ModuleList([
+            ModulatedSparseTransformerCrossBlock(
+                model_channels,
+                cond_channels,
+                num_heads=self.num_heads,
+                mlp_ratio=self.mlp_ratio,
+                attn_mode='full',
+                use_checkpoint=self.use_checkpoint,
+                use_rope=(pe_mode == "rope"),
+                share_mod=self.share_mod,
+                qk_rms_norm=self.qk_rms_norm,
+                qk_rms_norm_cross=self.qk_rms_norm_cross,
+            )
+            for _ in range(num_blocks)
+        ])
+
+        self.out_blocks = nn.ModuleList([])
+        if io_block_channels is not None:
+            for chs, prev_chs in zip(reversed(io_block_channels), [model_channels] + list(reversed(io_block_channels[1:]))):
+                self.out_blocks.append(
+                    SparseResBlock3d(
+                        prev_chs * 2 if self.use_skip_connection else prev_chs,
+                        model_channels,
+                        out_channels=chs,
+                        upsample=True,
+                    )
+                )
+                self.out_blocks.extend([
+                    SparseResBlock3d(
+                        chs * 2 if self.use_skip_connection else chs,
+                        model_channels,
+                        out_channels=chs,
+                    )
+                    for _ in range(num_io_res_blocks-1)
+                ])
+            
+        self.out_layer = sp.SparseLinear(model_channels if io_block_channels is None else io_block_channels[0], out_channels)
+
+        self.initialize_weights()
+        if use_fp16:
+            self.convert_to_fp16()
+
+    @property
+    def device(self) -> torch.device:
+        """
+        Return the device of the model.
+        """
+        return next(self.parameters()).device
+
+    def convert_to_fp16(self) -> None:
+        """
+        Convert the torso of the model to float16.
+        """
+        self.input_blocks.apply(convert_module_to_f16)
+        self.blocks.apply(convert_module_to_f16)
+        self.out_blocks.apply(convert_module_to_f16)
+
+    def convert_to_fp32(self) -> None:
+        """
+        Convert the torso of the model to float32.
+        """
+        self.input_blocks.apply(convert_module_to_f32)
+        self.blocks.apply(convert_module_to_f32)
+        self.out_blocks.apply(convert_module_to_f32)
+
+    def initialize_weights(self) -> None:
+        # Initialize transformer layers:
+        def _basic_init(module):
+            if isinstance(module, nn.Linear):
+                torch.nn.init.xavier_uniform_(module.weight)
+                if module.bias is not None:
+                    nn.init.constant_(module.bias, 0)
+        self.apply(_basic_init)
+
+        # Initialize timestep embedding MLP:
+        nn.init.normal_(self.t_embedder.mlp[0].weight, std=0.02)
+        nn.init.normal_(self.t_embedder.mlp[2].weight, std=0.02)
+
+        # Zero-out adaLN modulation layers in DiT blocks:
+        if self.share_mod:
+            nn.init.constant_(self.adaLN_modulation[-1].weight, 0)
+            nn.init.constant_(self.adaLN_modulation[-1].bias, 0)
+        else:
+            for block in self.blocks:
+                nn.init.constant_(block.adaLN_modulation[-1].weight, 0)
+                nn.init.constant_(block.adaLN_modulation[-1].bias, 0)
+
+        # Zero-out output layers:
+        nn.init.constant_(self.out_layer.weight, 0)
+        nn.init.constant_(self.out_layer.bias, 0)
+
+    def forward(self, x: sp.SparseTensor, t: torch.Tensor, cond: torch.Tensor) -> sp.SparseTensor:
+        h = self.input_layer(x).type(self.dtype)
+        t_emb = self.t_embedder(t)
+        if self.share_mod:
+            t_emb = self.adaLN_modulation(t_emb)
+        t_emb = t_emb.type(self.dtype)
+        cond = cond.type(self.dtype)
+
+        skips = []
+        # pack with input blocks
+        for block in self.input_blocks:
+            h = block(h, t_emb)
+            skips.append(h.feats)
+        
+        if self.pe_mode == "ape":
+            h = h + self.pos_embedder(h.coords[:, 1:]).type(self.dtype)
+        for block in self.blocks:
+            h = block(h, t_emb, cond)
+
+        # unpack with output blocks
+        for block, skip in zip(self.out_blocks, reversed(skips)):
+            if self.use_skip_connection:
+                h = block(h.replace(torch.cat([h.feats, skip], dim=1)), t_emb)
+            else:
+                h = block(h, t_emb)
+
+        h = h.replace(F.layer_norm(h.feats, h.feats.shape[-1:]))
+        h = self.out_layer(h.type(x.dtype))
+        return h
+    
+
+class ElasticSLatFlowModel(SparseTransformerElasticMixin, SLatFlowModel):
+    """
+    SLat Flow Model with elastic memory management.
+    Used for training with low VRAM.
+    """
+    pass