Dev:Source/Development/Todo/Render

Render & UI

• While rendering, manipulating images (like reload, resizing generated) can still crash Blender. Better image "owner" locking is required for 2.5 (T28477)
• While rendering, several UI changes can cause crashes (T24758)
• Rendering can't really use normal scene data if ui is interactive without causing all kinds of trouble, for examples and related issues see the item above this one.. and the reports (T26535)
• Renaming scene leads to missing rendered result in image editor and compositor (see (T30222))
• Rendering with File Output nodes could produce unwanted output images, see (T38605)
• Shaded draw mode (using render code for vertex colors) is most certainly not coming back
• Color Management can be communicated better, like when sampling colors in Image Window it confuses (could indicate such). Color Management also wasn't added backward compatible, disabling it gives dark results.
• Compositor "file out" node doesn't work for FSA, and as color management troubles too.
• FSA render uses temp files with names preventing other Blender instances to render too. (T28314)
• Texture nodes have been implemented by recursively (backwards) calling parent nodes, this gives issues for viewers, previews and threads in general.We will try to keep it stable, but the functionality for this is going to replaced with a better shader system in 2.6. (compositor and material nodes call nodes forward, sorted on dependency. Each node is only called once this way).
• Render display in Image window, for a window previously showing UV editor, doesn't restore correctly. (T26828). Code for this is too much spread around and fuzzy, needs full revision.
• Object transform is not possible during rendering T37019
• Don't render and warn when a driver or pre-render script can't be executed, a texture is missing, physics are not baked. Needed e.g. when renderfarms have scripts blocked.

Render Engine

• Raytracing black dots ((T20280))

• Known issue since 2.3x: Raytracing textures doesn't preserve tangents or derivatives, causing normalmaps or image textures or bumps to not show, or too blurred. Is for new shader system (2.6)
• Known issue since 2.3x: Raytraced shadows or reflections don't show up in Environment Maps. Postponed to 2.6 as well.
• Known issue since beginning: Raytracing doesn't support screen texture coordinates (on ray hits)
• Known issue: Oren Nayer diffuse doesn't work correct for Area Lights (Oren Nayer can't use volumetric integral)
• Using displacement texture + use normal from same texture gives unpredictable results. (T25532)
• Texture nodes disabled for displacement now, conflict in using it with render (needs owner for stack).
• 2.6 todo: for recode of shaders, be aware of errors in sampling transparent shadows (T25386)
• Stencil option in material only works a bit wacko, affecting its own channel too and multiplying effect on normals on each further channel. Fix is possible, but preferred is to wait for 2.6 redesign. (T26184)
• Known issue: Full Sample render doesn't work for Lens Flares.
• Raytraced soft shadows for sun and hemi depend on scene size ((T29756))
• wrong Environment Lighting caused by zenith color ((T28926))
• Shadow Only doesn't work with Environment Light ((T27017))
• SSS with small scattering distance can give artifacts with AA render in some cases ((T30743))
• Textures used for world/lamps can't be disabled like for material, was never implemented ((T33406))
• Using extremely small faces can cause normals to flip: (T34171)
• Implementation of "Cook Torrance" and "Blinn" specular are inaccurate and use wrong names; (T34564)
• Model with two UVs would use active UV layer for tangent space calculation, which gives different results in both viewport and render when activating different UV layers. (see T33810)
• Spot lamps with non-uniform scale don't render correctly (see T37071)
• Point cache for duplicated objects doesn't behave as it expected T39195
• Sampled motion blur shutter time is not centered around the current frame, but always after the frame. This should be fixed or an option added. (T39840)
• Shadow Only ignores the shadow color of lamps T41973
• Ray tracing and alpha does not really like each other T41985
• Tangent material shading doesn't work good for flat shading T41990
• Transparent shadows fail under certain circumstances. T39981
• Blend Sky is not reflected definitely by Environment Map. T41260
• Light group can be added from other scene to current one, bringing unwanted light sources T43432
• Specular/diffuse alpha gives undesired results with raytrace T44777
• Clipping code has numeric instabilities (T44950)
• Translucency has weird behavior when using normal map (T44987, T44988)
• Scaling instance to zero might other instances to disappear, T46937
• Shadow-only materials ignoring shadow color (T44875)
• Procedural textures might flicker in certain configurations (T48606)
• Shading artifacts in Blender Internal shadows (T50520)
• Edge enhance pass might create unexpected outlines (T51337)

Volume Rendering

In general: this feature is currently not in active maintenance, we need a new owner of the code.

• Volumes don't render inside transparent objects ((T20407))
• Add 'bounding box' texture mapping type (stretches 0,1 or -1,1 mapped to object instance's bounding box)
• Try to make the point density baking space stuff more intuitive
• Only the basis metaball with volumetric material is taken into account when rendering ((T20094))
• Volume and z-layer ((T28849))
• Problem with Rendering Lamps in volumetric Bodies ((T30322))
• Smoke doesn't receive light from his own particles ((T29766))
• Mirror inside volume does not reflect volume ((T31749))
• Point density texture is unpredictable for higher settings. [1]
• Volume rendering doesn't work together with mask layers when inside volumes (T33480)
• [#35383] Volume and Z depth error, render inside volumes. (T35383)
• Smoke volume and render layer behavior (T39142)
• Random integrator might cause flickers in animation T41594

Node Materials

• Threading issue with large memory requiring trees ((T24027))
• Material nodes are not supported for passes T41436

Node Textures

• Grouping texture nodes affects on data range T45696

Baking

• add option to smooth vertex colors as a post process after baking T35066.
• Baking to a low-res textures might miss pixels which lies on the UV island boundary T37681
• Vertex baking might cause AO artifacts T44178
• Support dupligroups T43553
• Modifier produces non deterministic effects T42015
• Update Blender side baking to support different topologies needed for adaptive subdivision T49405

Render Engine (Freestyle)

• NGons creating unwanted lines in Freestyle T40163

Render Engine (Eevee)

• Linear motion blur is not sufficient to express very fast rotating motions. Non-linear with bezier interpolation should do the trick, or maybe substep decomposition. T51480