Grass Maker for Mesh Terrain (wip)

Trying to make some basic grass/plants generator for mesh terrain.. (not terrain object).
(This is part of Mesh Terrain/Splatmap Tool)

FEATURES
– Editor plugin: Generates grass billboard planes(quads) over mesh surface (using raycast..)
– Checks splatmap color, if its over certain threshold, then add grass here..
– Atlas texture support for grass

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TODO
– Find: Better / realistic looking way to distribute grass/plants around terrain.. (Ideas: using splatmask? terrain surface angles? or just fill the whole scene randomly? or floodfill?)
– Fix: floating meshes (maybe can take raycast hit normal, then adjust border vertices using that..?)
– Add: position randomness
– Add: multiple grass/plant types (using atlas now)
– Add: grass options (scale, main color, variation, …)
– Add: billboard options (how many quad planes, what group shape: single, cross, …)
– Add: take vertex color from terrain, use in shader : done
– Grass islands/patches should also have less/shorter grass on patch borders..if that looks nicer.
– Could add trees, rocks into this later also..
– Optimized Quad plane > Use single triangle instead?
– Lawnmover script, why not! (just move vertices down or change atlas image to cut grass)
– Bending grass near player (shader: move vertices by player distance)
– Add probability percentage option for each grass type (now there are too many white flowers..) *Random weighted selection..
– Optimize far away grass (hide it if too far, fade in or show when closer)
– Distribution: less grass if lower mask threshold : Before: “if (maskC.g>0.75f)”, After: “if (Random.value>1-maskColor.g)”
– Fix shader: some problems with lights? (too dark in some areas/angles) : added custom surface shader lighting using this

PROBLEMS
– Cannot use GetPixel() to get pixel color from that position, with raycast & hit.textureCoord, if the mesh texture material is set tiled? : Just had to multiply hit.textureCoord with tiling value.
– Webplayer demo build would be 44 megabytes! Have to check whats happening there..

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IDEAS
– Raycast floodfill : Shoot raycast on terrain, if suitable mask color for grass, shoot more rays nearby and place grass (with scale based on original startpoint), until hit different mask color..

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INSPIRATION
– Grassy terrain/hill photo
– Grass/sand terrain render
– Outerra grass

RESOURCES
– Nvidia grass (some quad shapes here)
– Free skyboxes

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Image#2: Problems > Floating meshes (since the quad centerpoint is taken from single raycast hit..)

AFTER (26.6.2014).. floating shadow still quite annoying here..

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Image#3-4-5: Trying to get quad aligned with surface, without distorting texture.. argh, why I didnt do my maths homework at school ><

Almost solved (by a friend with some mathemagic), now there are those color lines to indicate end vertex positions on surface.. not yet sure what happens to texture when quad is stretched over there..

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Image#6: Added perlin noise to grass positions, looks ok from nearby:

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Image#7: Taking grass color/tint from current texture under it

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Image#8: Using sprite shader, looks nice also (no shadows or waving though..and  forgot to set bottom vertex alpha to 1) *click images for full size

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Image#9: Using texture atlas for grass (*btw. these plant textures are from : https://www.assetstore.unity3d.com/en/#!/content/6

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Image#10: 2 Sided lighting shader, added skybox and fog. (around 560 drawcalls, almost 2.5million tri’s)

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Image#11: New random distribution probability threshold & height scale from mask color. It gives those random smaller grasses nearby the normal grass area