| "instruction": "Car Paint Shader (two-lobe BSDF) `/home/user/Desktop/scene.blend` contains a UV sphere `PaintBall` at the origin (radius 1.0, 64x32 segments, smooth shaded) with a basic Principled BSDF material `CarPaint` whose Base Color is a dark blue (0.1, 0.1, 0.3). Launch Blender by running `blender` from a terminal. For this task, use `/opt/blender/blender` for Blender command-line or background runs when working on `scene.blend`.\n\nNo Coat / Sheen / Metallic is set. The scene has a camera at (0, -4, 0.8) looking at the origin, a three-point area light rig (KEY at (2,-2,3) E=400, FILL at (-2,-2,1) E=150, RIM at (0,1,2) E=200), a plain gray (0.1,0.1,0.1) world, Cycles 128 samples with denoise ON, view transform = 'Standard', exposure -1.5, resolution 512x512. Your task: rebuild the `CarPaint` material into an explicit two-lobe car-paint shader (metallic flake + clearcoat + sheen), render the scene at 512x512, and save both the .blend and the rendered PNG. ## Required material Rebuild `CarPaint` around a single Principled BSDF with these inputs: - Base Color : (0.1, 0.1, 0.3, 1.0) - dark metallic blue - Metallic : 0.9 - strong metal flake lobe - Roughness : 0.3 - broad metallic highlight - Coat Weight : 1.0 - full clearcoat layer - Coat Roughness : 0.03 - sharp clearcoat highlight - Coat IOR : 1.5 - Sheen Weight : 0.2 - subtle rim glow - Sheen Roughness : 0.5 - Sheen Tint : (1, 1, 1, 1) The Principled BSDF's output drives the Material Output's Surface input. The dual-lobe behaviour comes from the combination of the broad metallic lobe (Metallic=0.9, Roughness=0.3) and the sharp clearcoat lobe (Coat=1, Coat Roughness=0.03) layered on top. ## Render Set the render engine to Cycles, 512x512, 128 samples, denoise on, view transform 'Standard', exposure -1.5. Render with `bpy.ops.render.render(write_still=True)` to: - `/home/user/Desktop/render.png` and save the blend to: - `/home/user/Desktop/answer.blend` ## Requirements 1. `answer.blend` exists. 2. `answer.blend` opens cleanly in Blender. 3. `PaintBall` mesh is present with >= 1000 verts. 4. The sphere's material has a Principled BSDF node. 5. Principled.inputs['Coat Weight'] > 0.5. 6. Principled.inputs['Metallic'] > 0.7. 7. `/home/user/Desktop/render.png` exists and is 512x512. 8. Full-image mean luma is in [0.05, 0.35] (dark car body with bright specular). 9. Dual-highlight signature: inside a 60x60 ROI centred on the predicted KEY-light highlight pixel on the sphere (computed from the half-vector between the sphere->camera direction and the sphere->KEY light direction, then projected through the camera), the per-pixel luma standard deviation is >= 0.08. A single-lobe matte Principled BSDF produces a smooth gradient with low std; a two-lobe car paint produces both a broad metallic plateau AND a sharp clearcoat peak, spreading the luma distribution.", |
