RVMAT basics

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Theory

Lighting

Lighting and shading are what make 3D scene appealing. In real-time render we still have to simplify so the Artist must understand how shading works in engine to be able prepare the best realistic looking surfaces.

Real Virtuality counts lighting as T * (D.o + A) + S.o:

  • T = texture color
  • D = diffuse lighting (color, intensity and direction. ARMA engine has just one light source of directional light - sun or moon.) D is calculated as max(L.N,0)*sunLightColor - where L is light direction, N is surface direction (normal)
  • A = ambient lighting (color and intensity. It is always present at same intensity all over the scene and its value is done by overcast setting)
  • S = specular (setting of material glossiness and specularity)
  • o = direction of light (1 = pixel is lit, 0 = pixel is in shadow)

Simple materials count lighting per vertex by interpolating light direction between face edges (normals). It is similar to well known Gouraud shading model. More complex materials use per pixel normal orientation.

Values for shading calculations are combined from textures, effect bitmaps, engine light settings (config) and material settings (.rvmat).

Shadows

Shadows are calculated in ARMA engine two types, depending on values in Video options and each model setting.

Stencil buffer shadows are sharp and they are added after the whole scene has been drawn. Engine just subtracts diffuse light value on places where stencil shadow volume appeared. This results in speculars still being present in shadows. Also when ambient and diffuse settings of the material are not equal (and ForceDiffuse!=0) then resulting color isn't correct.

Shadow buffer makes one soft shadow map calculated on GCard for whole scene from the viewport. This affects the precision of the shadow.

Glossiness

Material specularity is defined by a curve (Bidirectional reflectance function) that says how much light is reflected under all angles. In Real Virtuality we are able to use:

  • Specular Power
  • Irradiance Table
  • Fresnel values

in .rvmat files.

Sections

Textures and materials are linked to each face separately so artist can have various materials on surface mapped with a single texture.

Everytime when Graphics Card (GPU) is instructed to draw with new parameters, we call it scene section. It is usually when new object (*.p3d), texture or material appears. Sections are generated each time when there is need to change parameters for rendering on Graphical Card (GPU). This is always when loading information from CPU about independent OBJECT, TEXTURE, MATERIAL or bone limit is exceeded on the card. Overhead in instruction transfer between CPU and GPU then lowers rendering performance which could be used to render hundreds polygons or textures etc.

Texture (TGA) is assigned to individual faces. Material (RVMAT) is assigned to same faces separately thus it is possible use various materials on surface covered with one UV and CO map. Yet then are generated another sections. In STAGE 0 is possible change with RVMAT also difusse component texture. Sections may differ in individual LODs.

Procedural textures

Besides TGA/PAA textures, Real Virtuality can work with maps generated in real-time procedurally - see Procedural Textures.

Normal Map

The Normal maps used in Arma are Tangent-space maps with the X+ Y- orientation (same as in Unreal Engine and 3dsmax renderer default setting).


RVMAT files

Those files are a sort of config.

Basic Surface Setting

Ambient

Ambient[] = { 0.9, 0.9, 0.9, 1 };

multiplies color values (color texture R,G,B,A) of the surface that is not lit by the main directional light.

Diffuse

Diffuse[] = { 0.9, 0.9, 0.9, 1 };

multiplies color values of the surface that lit by main directional light.

ForcedDiffuse

ForcedDiffuse[] = { 0, 0, 0, 0 };

those values help to simulate so called Translucency; part of the diffuse lighting that is reflected on surface in shadow. It works similar to ambient but with different lighting component. Unfortunately some shaders do not work well with forcedDiffuse.

ambient[] = { 1, 1, 1, 1 };
Diffuse[] = { 0.5, 0.5, 0.5, 1 };
ForcedDiffuse[] = { 0.5, 0.5, 0.5, 0 };

This combination makes the same result as the old HalfLighted vertex property (surface is lit the same from all sides, it appears flat)

For foliage surfaces there are special shaders that use also forcedDiffuse Alpha value setting for calculating how much light goes through (1 = all).

Emmisive

emmisive[] = { 0, 0, 0, 0 };

Emmisivesic - also called Luminescence. Values give amount of light that surface shines by himself. Use it for light-sources. It will appeal shining but will not lit anything around.

Specular

specular[] = { 0.3, 0.3, 0.3, 0 };

Used for making so called hotspot (in max it is Specular level+specular color). It is part of the light that is reflected from surface. Specular is calculated poer vertex or per pixel depending od specific shader.

SpecularPower

specularPower = 40;

Also called Glossiness. Defines how sharp the hot-spot will be. Some shaders use IRRADIANCE TABLE instead of this value.

MaterialSettings.jpg


  • All above mentioned settings can be calculated in some shaders per pixel using effect bitmaps.
  • All components are together used in calculation of surface shading:
pixel RGB on screen = (RVMAT ambient * RGB texture * Environment ambient)
+ (RVMAT diffuse * RGB texture * Environment diffuse * light direction)
+ (RVMAT forced diffuse * RGB texture * Environment diffuse)
+ (RVMAT emissive material * RGB texture)
+ (RVMAT specular * Environment diffuse * light direction)


Color values are usually in range 0-1, but it can be more. ARMA engine calculates light in high dynamic range, with values exceeding 0-255 RGB depth. Final RGB in monitor is calculated for each frame depending od eye/optics Aperture (shutter) settings setAperture/setApertureNew.

Realistic surfaces do not reflect 100% of incoming light. The more light is reflected as specular the less diffuse it has. Sum of diffuse, forced diffuse and reflected light should not exceed 1 BUT this is not true on ArmA real-time materials that do render just sunlight hot-spot and miss environmental light.

Diffuse for many usual surfaces is between 40%-80%. If you aim for maximum realistic surface settings, study photoreference. RVMAT settings allow you to put as much color range as possible in texture and than modify it to realistic values with maximum dynamic range.

Realistic surfaces usually reflect directional and scattered light the same way - Diffuse and Ambient are equal. Real Virtuality has environment settings with values for diffuse and ambient (scene contrast) based on real world light recording. Color Calibration. It is not wise to compensate contrast in material settings.

Lower diffuse values are used for spongy materials (some light is transfered to forceDiffuse). Lower ambient values can be used on surfaces where global ambient should be reduced, such as Interiors. It is usually made using Ambient Light maps.

Specular color

Usually we set RGB values color neutral. But sometimes it is effective to tint color in rvmat. Most obvious it is in specular settings of some glossy metal surfaces.

If I want a specific color, I count:

X = B / (Sp * Db)

B.. desired color of hot-spot

Sp.. actual Specular setting of hot-spotmaterial

Db.. color of environment light (Ambient and Diffuse change during day and overcast) O2 environment editor shows actual colors used in buldozer preview.

X ..number that i use to multiply Specular to get desired color.

RenderFlags

Special shading property that are used instead of old VERTEX LIGHTING PROPERTY settings.

renderFlags[] = { flag1, flag2 };
Flag Name Description
NoZWrite Face is not count in Z-buffer. Used for alpha-transparent surfaces laid over another faces to fix shadow artifacts. (for example squad logo)
NoColorWrite Disables calculation in color channels. Face is calculated just in alpha and Z-buffer.
NoAlphaWrite Disables calculation in alpha channels. Used for transparent glass that has 2 pass material.
AddBlend Allows adding alpha-transparent surface color to the background. Used for fire particles.
LandShadow For terrain.

AlphaTest32
Alphatest64
Alphatest128

Defines threshold where pixel becomes transparent at drop off to discrete alpha. The bigger value, the more pixels are used
Road
NoTiWrite
NoReceiveShadow
NoLODBlend
Dummy0

Always in Shadow can be achieved with setting RVMAT diffuse[] = { 0, 0, 0, 0 } + reasonable specular reduction.

Light Mode

Setting of various kinds of light calculation:

mainLight = "Sun";

Possible values are:

  • None
  • Sun
  • Sky
  • Horizon
  • Stars
  • SunObject
  • SunHaloObject
  • MoonObject
  • MoonHaloObject

Fog Mode

Setting of various kinds of fog calculation:

fogMode = "Alpha";

Possible values are:

  • none - no fog
  • fog - fog used by usual opaque objects; the more the object is covered by fog, the closer its color is to fog color
  • alpha - fog used by objects with alpha; the more the object is covered by fog, the more transparent it is
  • fogAlpha - combination of both above approaches; used for roads (alpha-out could be quicker than fogging); can be used to fade away objects when object is not just normally fogging
  • fogSky - fog for sky objects (moon, stars)

Shader-Specific Setting

Selecting shader.

PixelShaderID = "xxx";
VertexShaderID = "xxx";

Each shader uses specific "Stages".

class StageX

Each stage define parameters for shader calculation, usually as links to effect bitmaps.

  • texture = (name and path to effect bitmap texture)

Must obey texture naming conventions Texture Naming Conventions otherwise there will be no proper automatic conversion made from TGA to PAA.

  • Filter = "Anizotropic";

Default is Anizotropic, but in some situations you can use Point, Linear, Trilinear.

  • uvSource = "tex";

can be: none, tex, tex1 (second UV set), pos, norm, worlPos, worldNorm, texShoreAnim, texCollimator, texCollimatorInv

  • class uvTransform

Offset, deformation or repeating ot texture in given UV set.

Material Types

Inside O2 Material editor exist examples for most of shaders - see Oxygen 2 - Manual - MAT plugin.

Wikipage Vertex shader Pixel shader Notes
Material - General material Basic Normal
Material - DXTA material Basic NormalDXTA
Material - Basic detail map Basic Detail
Basic White
Basic WhiteAlpha
Material - Basic glass Basic AlphaShadow
Material - Normal map NormalMap NormalMap
Material - Normal map HQ specular NormalMap NormalMapSpecularMap NOHQ+SM
NormalMap NormalMapSpecularDIMap NOHQ+SMDI
Material - Normal map HQ detail map specular NormalMap NormalMapDetailSpecularMap NOHQ+DT+SM
NormalMap NormalMapDetailSpecularDIMap NOHQ+SMDI+DT
Material - Basic normal detail NormalMapDiffuse NormalMapDiffuse NormalMapDetail, per vertex lit
Water Water
Material - Water simple WaterSimple WaterSimple
NormalMapThrough NormalMapThrough
NormalMapThrough NormalMapThroughSimple
Material - Basic Tree crown NormalMapSpecularThrough NormalMapSpecularThrough TreeCrown - colormap must be with continuous alpha
NormalMapSpecularThrough NormalMapSpecularThroughSimple
NormalMapThroughNoFade NormalMapThrough
NormalMapThroughNoFade NormalMapThroughSimple
NormalMapSpecularThroughNoFade NormalMapSpecularThrough
NormalMapSpecularThroughNoFade NormalMapSpecularThroughSimple
Material - Detail macro AS BasicAS DetailMacroAS DT+MC+AS
Material - Normal map macro AS NormalMapAS NormalMapMacroAS
Material - Normal map HQ specular macro AS NormalMapAS NormalMapMacroASSpecularMap NOHQ+MC+AS+SM
NormalMapAS NormalMapMacroASSpecularDIMap NOHQ+SMDI+MC+AS
Material - Normal map HQ detail specular macro AS NormalMapAS NormalMapDetailMacroASSpecularMap NOHQ+DT+MC+AS+SM
NormalMapAS NormalMapDetailMacroASSpecularDIMap NOHQ+SMDI+DT+MC+AS
Material - Normal map detail macro AS NormalMapDiffuseAS NormalMapDiffuseMacroAS NO+DT+MC+AS
Material - Basic glass reflectance Glass Glass
Terrain TerrainX X is number from 1 to 15 and presents mask as per which is choosen combination from 4 layers
Material - Antiwater Basic AlphaNoShadow in combination with empty alpha texture clears water from ship and is shadowless
Terrain TerrainSimpleX X is number from 1 to 15 and presents mask as per which is choosen combination from 4 layers
Super_shader Super Super SM 3.0 - shader with Fresnel for Arma 2
Multimaterial Multi Multi SM 3.0 - shader with multiple submaterials for Arma 2
Material - Tree Tree TreeNoFade SM 3.0 - shader for Arma 2 vegetation
Material - TreePRT TreePRT TreePRT SM 3.0 - shader for Arma 2 vegetation
Skin_shader
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Shaders

Pixel Shaders

Shader Name Description
Normal diffuse color modulate, alpha replicate
NormalDXTA diffuse color modulate, alpha replicate, DXT alpha correction
NormalMap normal map shader
NormalMapThrough normal map shader - through lighting
NormalMapGrass normal map shader - through lighting
NormalMapDiffuse
Detail detail texturing
Interpolation
Water sea water
WaterSimple small water
White
WhiteAlpha
AlphaShadow shadow alpha write
AlphaNoShadow shadow alpha (no shadow write
Dummy0
DetailMacroAS detail with ambient shadow texture
NormalMapMacroAS normal map with ambient shadow texture
NormalMapDiffuseMacroAS diffuse normal map with ambient shadow texture
NormalMapSpecularMap normal map with specular map
NormalMapDetailSpecularMap normal map with detail and specular map
NormalMapMacroASSpecularMap normal map with ambient shadow and specular map
NormalMapDetailMacroASSpecularMap normal map with detail and ambient shadow and specular map
NormalMapSpecularDIMap normal map with specular map, diffuse is inverse of specular
NormalMapDetailSpecularDIMap normal map with detail and specular map, diffuse is inverse of specular
NormalMapMacroASSpecularDIMap normal map with ambient shadow and specular map, diffuse is inverse of specular
NormalMapDetailMacroASSpecularDIMap normal map with detail and ambient shadow and specular map, diffuse is inverse of specular
Terrain1 terrain - X layers
Terrain2 terrain - X layers
Terrain3 terrain - X layers
Terrain4 terrain - X layers
Terrain5 terrain - X layers
Terrain6 terrain - X layers
Terrain7 terrain - X layers
Terrain8 terrain - X layers
Terrain9 terrain - X layers
Terrain10 terrain - X layers
Terrain11 terrain - X layers
Terrain12 terrain - X layers
Terrain13 terrain - X layers
Terrain14 terrain - X layers
Terrain15 terrain - X layers
TerrainSimple1 terrainSimple - X layers
TerrainSimple2 terrainSimple - X layers
TerrainSimple3 terrainSimple - X layers
TerrainSimple4 terrainSimple - X layers
TerrainSimple5 terrainSimple - X layers
TerrainSimple6 terrainSimple - X layers
TerrainSimple7 terrainSimple - X layers
TerrainSimple8 terrainSimple - X layers
TerrainSimple9 terrainSimple - X layers
TerrainSimple10 terrainSimple - X layers
TerrainSimple11 terrainSimple - X layers
TerrainSimple12 terrainSimple - X layers
TerrainSimple13 terrainSimple - X layers
TerrainSimple14 terrainSimple - X layers
TerrainSimple15 terrainSimple - X layers
Glass glass shader with environmental map
NonTL very simple 2D pixel shader
NormalMapSpecularThrough normal map shader - through with specular lighting
Grass grass shader - alpha discretized
NormalMapThroughSimple simple version of NormalMapThrough shader
NormalMapSpecularThroughSimple simple version of NormalMapSpecularThrough shader
Road road shader
Shore shore shader
ShoreWet shore shader for the wet part
Road2Pass road shader - second pass
ShoreFoam shore shader for the foam on the top of the shore
NonTLFlare shader to be used for flares
NormalMapThroughLowEnd substitute shader for NormalMapThrough shaders for low-end settings
TerrainGrass1 terrain grass - X layers
TerrainGrass2 terrain grass - X layers
TerrainGrass3 terrain grass - X layers
TerrainGrass4 terrain grass - X layers
TerrainGrass5 terrain grass - X layers
TerrainGrass6 terrain grass - X layers
TerrainGrass7 terrain grass - X layers
TerrainGrass8 terrain grass - X layers
TerrainGrass9 terrain grass - X layers
TerrainGrass10 terrain grass - X layers
TerrainGrass11 terrain grass - X layers
TerrainGrass12 terrain grass - X layers
TerrainGrass13 terrain grass - X layers
TerrainGrass14 terrain grass - X layers
TerrainGrass15 terrain grass - X layers
Crater1 Crater rendering - X craters
Crater2 Crater rendering - X craters
Crater3 Crater rendering - X craters
Crater4 Crater rendering - X craters
Crater5 Crater rendering - X craters
Crater6 Crater rendering - X craters
Crater7 Crater rendering - X craters
Crater8 Crater rendering - X craters
Crater9 Crater rendering - X craters
Crater10 Crater rendering - X craters
Crater11 Crater rendering - X craters
Crater12 Crater rendering - X craters
Crater13 Crater rendering - X craters
Crater14 Crater rendering - X craters
Sprite Shader used for sprite rendering - it uses SoftParticle approach
SpriteSimple Shader used for sprite rendering - no SoftParticle approach
Cloud Shader used for clouds
Horizon Shader used for the horizon
Super Super shader
Multi Multi shader
TerrainX terrain - general number of layers
TerrainSimpleX terrainSimple - general number of layers
TerrainGrassX terrain grass - general number of layers
Tree Tree shader
TreePRT Tree shader - very cheap shader with PRT
TreeSimple Tree shader - simpler version of Tree
Skin Human skin - derived from Super shader
CalmWater calm water surface
TreeAToC tree with alpha to coverage
GrassAToC grass with alpha to coverage
TreeAdv advanced tree crown shader
TreeAdvSimple advanced tree crown shader
TreeAdvTrunk advanced tree shader
TreeAdvTrunkSimple advanced tree shader
TreeAdvAToC advanced tree crown shader
TreeAdvSimpleAToC advanced tree crown shader
TreeSN Tree shader width simple noise
SpriteExtTi Sprite used for vehicles covering
TerrainSNX terrain - general number of layers + satellite normal map
InterpolationAlpha
VolCloud Shader used for volumetric cloud - it uses SoftParticle approach
VolCloudSimple Shader used for volumetric cloud - no SoftParticle approach
UnderwaterOcclusion Shader used for underwater occlusion object
SimulWeatherClouds SimulWeather clouds
SimulWeatherCloudsWithLightning SimulWeather clouds with lightning
SimulWeatherCloudsCPU SimulWeather clouds with CPU distance fading
SimulWeatherCloudsWithLightningCPU SimulWeather clouds with lightning and CPU distance fading
SuperExt skyscraper & building, intended as super shader light version
SuperHair super shader for hair rendering
SuperHairAtoC super shader for hair rendering, atoc version
Caustics shader for caustics effect
Refract shader for refractions _ARMA3_REFRACTION
SpriteRefract _ARMA3_REFRACTION_SPRITES - Shader used for sprite rendering with refraction - it uses SoftParticle approach
SpriteRefractSimple _ARMA3_REFRACTION_SPRITES - Shader used for sprite rendering with refraction- no SoftParticle approach
SuperAToC Super shader AToC variant
NonTLFlareNew shader to be used for flares, new HDR version
NonTLFlareLight shader to be used for flares from dynamic lights (not sun)
TerrainNoDetailX terrainX without detail map
TerrainNoDetailSNX terrainSNX without detail map
TerrainSimpleSNX terrainSNX without parallax mapping
NormalPiP shader for PiP screens
NonTLFlareNewNoOcclusion same as NonTLFlareNew, but without occlusion test
Empty empty shader, does not output anything (used only for depth output)
Point Shader used for point lights
TreeAdvTrans same as TreeAdv, but there is translucency map in alpha channel of MCA texture ( instead of AO)
TreeAdvTransAToC same as TreeAdv, but there is translucency map in alpha channel of MCA texture ( instead of AO)
Collimator special shader for collimator
LODDiag shader for lod diagnostics
DepthOnly Special replacement for AlphaOnly for priming non- alpha objects
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Vertex Shaders

Shader Name Description
Basic N/A
NormalMap normal map
NormalMapDiffuse normal map + detail map
Grass
Dummy1
Dummy2
ShadowVolume shadow volumes
Water per-vertex water animation
WaterSimple per-vertex water animation (without foam)
Sprite particle effects
Point anti-aliased points
NormalMapThrough normal map - tree shader
Dummy3
Terrain one pass terrain, no alpha mask - based on VSNormalMapDiffuse
BasicAS ambient shadow
NormalMapAS normal map with ambient shadow
NormalMapDiffuseAS diffuse normal map with ambient shadow

Glass /*glass shader*/ \

NormalMapSpecularThrough normal map with specular - tree shader
NormalMapThroughNoFade normal map - tree shader - without face fading
NormalMapSpecularThroughNoFade normal map with specular - tree shader - without face fading
Shore sea shore - similar to Terrain
TerrainGrass grass layer - similar to Terrain
Super Super shader - expensive shader containing all common features
Multi Multi shader - shader with multiple layers suitable for huge surfaces like houses
Tree Tree shader - cheap shader designed for trees and bushes
TreeNoFade Tree shader - cheap shader designed for trees and bushes - without face fading
TreePRT Tree shader - very cheap shader designed for trees and bushes
TreePRTNoFade Tree shader - very cheap shader designed for trees and bushes - without face fading
Skin Human skin - derived from Super shader
CalmWater calm water surface - special shader
TreeAdv advanced tree crown shader VSTreeAdv
TreeAdvTrunk advanced tree crown shader VSTreeAdvTrunk
VolCloud volumetric clouds
Road roads
UnderwaterOcclusion underwater occlusion object vertex shader
SimulWeatherClouds simul weather clouds
SimulWeatherCloudsCPU simul weather clouds with CPU distance fading
SpriteOnSurface sprite on surface
TreeAdvModNormals advanced tree crown shader with modified vertex normals
Refract vertex shader for refractions - _ARMA3_REFRACTION
SimulWeatherCloudsGS simul weather clouds with geom shader
BasicFade basic with face fading (based on the angle with camera direction
Star Similar to Point but only for drawing stars
TreeAdvNoFade advanced tree crown shader - no face fading
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You can find More about material settings in Material Templates.

Physical Properties

Materials are also used in geometries for definition of physical properties.

Parameters for engine are saves into material tables *.bisurf and reference to them from material looks like:

surfaceInfo = "data\wood.bisurf";

Such .bisurf file with physical properties looks like:

density = 2500;				// density of homogeneous object in kg/m³ - see https://en.wikipedia.org/wiki/List_of_elements_by_density
thickness = 10;				// non-homogeneous component casing thickness in mm, implemented since Arma 2: Operation Arrowhead
rough = 0.1;
dust = 0.1;
bulletPenetrability = 150;	// distance in mm bullet (with speed 1000m/s) travels before it fully stops, simulation for calculation simplification calculate linear braking
							// (ergo on third of distance is bullet decelerated to two thirds of original speed)
soundEnviron = Empty;
isWater = false;

See more about penetration in Bullet penetrability.

When components in Your model got materials with references to physical properties then use script which sets weight.