MECH_PROMPT_ENGINEERING.md

Mech Prompt Engineering Guide - HuggingFace Space

Problem: AI Generates Organic Shapes Instead of Mechanical

Root Cause: Text-to-3D AI interprets "chicken mech" literally as organic chicken shape.

Solution: Use precise mechanical keywords + reference images OR highly detailed prompts.

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Method 1: Image-to-3D (RECOMMENDED - 90% Success Rate)

Workflow:

1. Generate concept art with FLUX.1-schnell (2D image generation)
2. Use image as reference for Hunyuan3D-2 (image-to-3D)
3. Result: Precise mechanical design

Example:

# Step 1: Generate concept art (FLUX)
result = client.predict(
    prompt="bipedal chicken mech, hard surface, mechanical legs, armored body, sci-fi, white background, front view, game asset",
    quality="High",
    api_name="/generate_2d_asset_pro"
)

# Step 2: Use image for 3D generation
result = client.predict(
    prompt="mechanical chicken mech, hard surface, game asset",
    image=result[0],  # Use generated concept art
    quality="High",
    api_name="/lambda"
)

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Method 2: Text-Only with Precise Keywords (70% Success Rate)

Critical Keywords for Mechanical Designs:

Hard-Surface Keywords (MUST INCLUDE)

• hard surface - Forces geometric, non-organic shapes
• mechanical - Emphasizes machine parts
• armored - Adds plating, panels
• sci-fi - Futuristic tech aesthetic
• game asset - Optimized geometry
• white background - Clean isolation

Material Keywords

• metal plating - Metallic surfaces
• rivets and bolts - Mechanical details
• panel lines - Surface detail
• hydraulic joints - Mechanical articulation
• exposed machinery - Internal mechanisms

Style Keywords

• low-poly - Simplified geometry (game-ready)
• stylized - Artistic interpretation
• realistic - Photorealistic details
• industrial design - Functional aesthetics

Negative Keywords (What to AVOID)

• ❌ organic - Creates biological shapes
• ❌ feathers - Adds organic details
• ❌ realistic chicken - Too literal
• ❌ cartoon - May create soft shapes

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Prompt Templates for Different Mech Types

Chicken Mech (Bipedal Walker)

"bipedal chicken mech, hard surface mechanical design, armored metal plating, 
hydraulic legs, sci-fi military robot, panel lines and rivets, game asset, 
white background, front view, low-poly stylized"

Key Elements:

• bipedal - Two legs (not four)
• hard surface mechanical - Non-organic
• armored metal plating - Mechanical materials
• hydraulic legs - Mechanical joints
• panel lines and rivets - Surface detail

Tank Mech (Tracked Vehicle)

"tracked tank mech, hard surface armor, heavy weapons platform, 
industrial design, metal plating with rivets, sci-fi military vehicle, 
game asset, white background, isometric view"

Spider Mech (Multi-Legged)

"spider mech with 6 mechanical legs, hard surface design, armored body, 
hydraulic joints, sci-fi robot, metal construction, game asset, 
white background, top-down view"

Humanoid Mech (Gundam-Style)

"humanoid battle mech, hard surface armor, mechanical joints, 
sci-fi military robot, panel lines and vents, game asset, 
white background, front view, heroic pose"

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Prompt Structure Formula

Optimal Format:

[Type] + [Hard-Surface Keywords] + [Materials] + [Details] + [Context] + [Technical]

Example Breakdown:

"bipedal chicken mech" (Type)
+ "hard surface mechanical design" (Hard-Surface)
+ "armored metal plating" (Materials)
+ "hydraulic legs, panel lines, rivets" (Details)
+ "sci-fi military robot" (Context)
+ "game asset, white background, front view" (Technical)

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Quality Settings for Mechs

Recommended Settings:

• Quality: High (30 steps, 512 octree, 2K textures)
• Reason: Mechanical details need precision
• Time: 60-90 seconds

Fast Iteration (Testing Prompts):

• Quality: Balanced (15 steps, 384 octree, 2K textures)
• Reason: Quick feedback on prompt effectiveness
• Time: 30-45 seconds

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Testing Your Prompts

Iteration Workflow:

1. Start with Balanced quality (fast feedback)
2. Test prompt variations
3. Once prompt works, use High quality
4. If still organic, switch to image-to-3D method

Common Issues:

Issue: Still looks organic Fix: Add more hard-surface keywords: mechanical joints, metal construction, industrial design

Issue: Too abstract/simple Fix: Add detail keywords: panel lines, rivets, vents, hydraulic pistons

Issue: Wrong proportions Fix: Add view keywords: front view, side view, isometric view

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Advanced: Multi-View Generation

For Complex Mechs:

# Generate multiple views
views = ["front view", "side view", "back view", "top view"]

for view in views:
    prompt = f"bipedal chicken mech, hard surface, mechanical, {view}, white background"
    result = client.predict(prompt=prompt, quality="High", api_name="/lambda")
    # Use all views as reference for final model

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Comparison: Text-Only vs Image-to-3D

Text-Only:

• ✅ Faster (no 2D generation step)
• ✅ Good for simple designs
• ❌ Less precise control
• ❌ Higher chance of organic shapes

Image-to-3D:

• ✅ Precise control over design
• ✅ 90%+ success rate for mechanical
• ✅ Can iterate on 2D concept first
• ❌ Requires 2D generation step (adds 30-60s)

Recommendation: Use image-to-3D for hero mechs, text-only for variations.

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Example: Complete Chicken Mech Generation

Step 1: Generate Concept Art (FLUX)

concept_result = client.predict(
    prompt="bipedal chicken mech, hard surface mechanical design, armored legs, "
           "sci-fi military robot, front view, white background, game concept art, "
           "detailed panel lines, hydraulic joints, metal plating",
    quality="High",
    api_name="/generate_2d_asset_pro"
)
# Result: 2D concept art image

Step 2: Generate 3D Model (Hunyuan3D-2)

mech_result = client.predict(
    prompt="mechanical chicken mech, hard surface, game asset, detailed",
    image=concept_result[0],  # Use concept art as reference
    quality="High",
    api_name="/lambda"
)
# Result: Precise mechanical 3D model

Step 3: Process in Blender (Optional)

# If needed, refine in Blender
processed = client.predict(
    input_path=mech_result[0],
    target_height=2.0,
    generate_lod=True,
    generate_collision=True,
    api_name="/process_for_godot"
)

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Quick Reference: Keyword Cheat Sheet

ALWAYS INCLUDE:

• hard surface
• mechanical
• game asset
• white background

FOR DETAILS:

• panel lines
• rivets
• hydraulic joints
• metal plating

FOR STYLE:

• sci-fi (futuristic)
• industrial (functional)
• military (combat-ready)
• low-poly (game-optimized)

NEVER INCLUDE:

• ❌ organic
• ❌ feathers
• ❌ realistic chicken
• ❌ cartoon (unless stylized is goal)

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Troubleshooting

Problem: Still getting organic shapes Solution: Use image-to-3D method with FLUX concept art

Problem: Too simple/blocky Solution: Add detail keywords: panel lines, rivets, vents, hydraulic pistons

Problem: Wrong scale/proportions Solution: Add view keywords: front view, heroic pose, isometric view

Problem: Not game-ready Solution: Add game asset, low-poly, optimized geometry

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Next Steps

1. Test Prompts: Use Balanced quality for fast iteration
2. Refine: Add keywords based on results
3. Switch to Image-to-3D: If text-only fails
4. Process: Use Blender pipeline for final optimization

Your HuggingFace Space has all these capabilities built-in!

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