248 lines
12 KiB
Text
248 lines
12 KiB
Text
README.materials
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This README describes the materials.xml file format. It is targeted at those
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wanting to change the appearance of the scenery in FlightGear.
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As is the norm in FG, the materials.xml file is a properties file. However,
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it is only read on startup, is not part of the main property tree and cannot
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be changed at runtime.
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The properties file consists of a number of <material> entries, each of which
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describes a single visually distinct terrain material in the FG world.
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The rest of this document describes the children tags of the <material> entry.
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name : Scenery type names that map to this material. These are typically taken
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from landclass definitions created by TerraGear. Multiple scenery types
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may map to a single material. This is recommended to minimize texture
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memory usage.
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condition : A condition statement used to activate the material. Note that this
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if evaluated once at start-up.
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texture : A relative path to an SGI RGB, PNG or DDS file containing a texture
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for the material. RGB and PNG are recommended for platform compatibility.
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You may define more than one <texture> element, in which case the scenery
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loader will choose one texture for each contiguous set of scenery
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triangles.
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texture-set : If using an effect (see below), it may be necessary to define more
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than one texture. The texture-set element has multiple <texture> element
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children which may then be referenced by the effect. You may define more
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than one <texture-set> element, in which case the scenery loader will
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choose one texture for each contiguous set of scenery triangles.
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object-mask : An optional bitmap file used to control random placement of lights,
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buildings and vegetation on the terrain. The green channel mask is used
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for random vegetation placement, the blue channel for buildings and lights.
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and the red channel controls the rotation of buildings (0.0 is North, 0.5
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is South). Fractional colour values can be used to give a probability of
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placement. Multiple object-masks may be defined to match up with <texture>
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or <texture-set> elements.
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effect : The effect to be used for this material. (default:
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Effects/terrain-default)
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ambient, diffuse, specular, emissive, and shininess are copied into the
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parameter section of the effect created for this material.
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parameters : Additional parameters to be used in the effect. See README.effects for format information.
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wrapu : True if the texture should repeat horizontally over a surface, false if
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it should not repeat (default: true).
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wrapv : True if the texture should repeat vertically over a surface, false if
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it should not repeat (default: true).
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mipmap : True if the texture should be mipmapped, false otherwise. (default: true).
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xsize : The horizontal size of a single texture repetition, in meters.
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ysize : the vertical size of a single texture repetition, in meters
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light-coverage : The coverage of a single point of light in m^2. 0 indicates no
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lights at all. Minimum value is 1000m^2. May be masked by the blue channel
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of an object-mask. Lights are all generated 3m above the surface, and
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have random colour (50% yellow, 35% white, 10% orange, 5% red)
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ambient : The ambient light colour for the material, specified as separate
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r, g, b, a components (default: all color components 0.2, alpha 1.0).
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diffuse : The diffuse light colour for the material, specified as separate
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r, g, b, a components (default: all color components 0.8, alpha 1.0).
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specular : The specular light colour for the material, specified as separate
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r, g, b, a components (default: all color components 0.0, alpha 1.0).
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emissive : The emissive light colour for the material, specified as separate
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r, g, b, a components (default: all color components 0.0, alpha 1.0).
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solid : Whether the surface is solid from an FDM perspective. If it is not
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solid, it is assumed that the material models a fluid (water) surface.
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(default: true).
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friction-factor : The friction factor for that material. The normalized
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factor can be used by a FDM to post-multiply all contact friction forces
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with that factor. That is the more slippery a material is the smaller this
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value should be. (default: 1.0 for Dry concrete/Asphalt).
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rolling-friction : the gear rolling rolling-friction coefficient for this
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particular material. (default: 0.02 for Dry concrete/Asphalt).
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bumpiness : normalized bumpiness factor for this particular terrain.
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(default: 0.0 for a smooth surface).
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load-resistance : a pressure value how much force per surface area this
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surface can carry without deformation. The value should be in N/m^2
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(default: 1e30).
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glyph : group that defines one letter/digit/symbol in a font texture
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sub-entries: name, left (default: 0.0), right (default: 1.0)
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(left and right describe the horizontal position in the texture.)
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wood-coverage : The coverage of trees in areas marked as woodland in
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m^2. A lower number means a higher density of trees. A value of
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0 indicates no woods. May be masked by the green channel of an
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object-mask. (default: 0)
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tree-range-m : The range at which trees become visible. Note that this
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is not absolute, as trees are loaded in blocks. A lower number means
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trees will not become visible until you are closer.
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tree-texture : A texture to use for the trees. Typically this will contain around
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8 different trees in a row, duplicate 4 times. From bottom to top, the
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rows contain
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* summer textures
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* summer snow texture
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* winter texture
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* winter snow texture
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Each tree must have space at the top. For a 512x512 texture sheet, this
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should be 8 pixels. Otherwise subsequent rendering results in "top hats"
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above trees in the distance where the trunk of the tree above in the
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textures sheet bleeds downwards when the mipmaps are generated.
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tree-varieties : The number of different trees defined in the tree-texture
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horizontally. (default: 1)
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tree-height-m : The average height of the trees. Actual tree height will
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vary by +/- 50%. (default: 0)
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tree-width-m : The average width of the tree cover. Actual tree width will
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vary by +/- 50%. (default 0)
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tree-max-density-angle-deg : The slope angle at which trees begin to thin out
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as the slope is too steep to support the full coverage. Shallower
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slopes have maximum wood-coverage. Steeper slopes have fewer trees.
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(default : 45)
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tree-zero-density-angle-deg : The angle at which the slope is too steep to
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support significant vegetation. Steeper slopes have no trees.
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(default : 60)
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object-max-density-angle-deg : The angle at which objects and buildings become
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less dense due to a steep slope. (default : 20)
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object-zero-density-angle-deg : The angle at which the slope is too steep to build
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on. No object/buildings will be placed on slopes steeper than this.
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(default : 30)
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object-group : A group of random objects to be placed on the surface. Contains
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<range-m> and one or more <object> children.
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range-m : The distance at which objects within this object-group become
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visible. Note that for realism, 60% of the objects will become visible
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at <range-m>, 30% at 1.5*<range-m>, and 10% at 2*<range-m>.
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(default: 2000)
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object : A set of random objects to be placed. Contains <coverage-m2>, <path>
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and <heading> children.
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coverage-m2 : The coverage of a single object in m2. Lower values mean a higher
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density. Minimum value is 1000.
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spacing-m : The minimum space between this object and any other on the surface in
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meters. This helps to avoid objects being placed ontop of each other.
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(default 20)
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path : Path relative to FG_ROOT to a model definition, usually .ac or .xml file.
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More than one <path> may be included within the <object> tag, in which
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case a single <path> is chosen at random for each individual object
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placement.
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heading-type : Indicator of how the heading of the random objects should be
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determined. Valid values are:
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fixed - Objects all point North. Default.
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random - Objects are assigned an individual random heading
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mask - Rotation is taken from the red channel of the object-mask
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billboard - Object is always rotated to face camera - expensive
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Random Buildings
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================
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Random Buildings come in three sizes, with individual constraints.
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Small buildings. These have different textures on the sides compared to the front and back.
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Small buildings are never deeper than they are wide.
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Medium buildings, which are never taller than they are wide.
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Large buildings. There are no constraints on their width, depth or height.
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building-coverage : The coverage of random buildings in areas marked for random objects in
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m^2. A lower number means a higher density of buildings. A value of
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0 indicates no buildings. May be masked by the blue channel of an
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object-mask. (default: 0)
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building-spacing-m : The minimum spacing between random buildings and other buildings
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or random objects. This helps avoid objects being placed on top of each other.
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(default: 5)
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building-small-ratio: Ratio of small buildings. These buildings are 1-3 stories
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in height, and may have a pitched roof. Fraction of small buildings is
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(<building-ratio-small> / (<building-ratio-small> + <building-ratio-medium>
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+ <building-ratio-large>). (default: 0.8)
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building-medium-ratio : Ratio of medium buildings. These buildings are 3-6 stories in
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height, and have a flat roof. (default: 0.15)
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building-large-ratio : Ratio of large buildings. These buildings are 5-10 stories in
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height, and have a flat roof. (default 0.05)
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building-small-pitch : Fraction of small buildings with pitched roofs. (default 0.8)
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building-medium-pitch : Fraction of small buildings with pitched roofs. (default 0.2)
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building-large-pitch : Fraction of small buildings with pitched roofs. (default 0.1)
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building-small-min-floors : Minimum number of floors for a small building. (default 1)
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building-small-max-floors : Maximum number of floors for a small building. (default 3)
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building-medium-min-floors : Minimum number of floors for a medium building. (default 3)
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building-medium-max-floors : Maximum number of floors for a medium building. (default 8)
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building-large-min-floors : Minimum number of floors for a medium building. (default 5)
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building-large-max-floors : Maximum number of floors for a medium building. (default 20)
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building-small-min-width-m : Minimum width of small buildings. (default 15)
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building-small-max-width-m : Maximum width of small buildings. (default 60)
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building-small-min-depth-m : Minimum depth of small buildings. (default 10)
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building-small-max-depth-m : Maximum depty of small buildings. (default 20)
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building-medium-min-width-m : Minimum width of medium buildings. (default 25)
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building-medium-max-width-m : Maximum width of medium buildings. (default 50)
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building-medium-min-depth-m : Minimum depth of medium buildings. (default 20)
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building-medium-max-depth-m : Maximum depty of medium buildings. (default 50)
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building-large-min-width-m : Minimum width of large buildings. (default 50)
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building-large-max-width-m : Maximum width of large buildings. (default 75)
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building-large-min-depth-m : Minimum depth of large buildings. (default 50)
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building-large-max-depth-m : Maximum depty of large buildings. (default 75)
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building-texture : The texture used for all buildings. See Docs/buildings.png for details.
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(default Texture/buildings.png)
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building-lightmap: Emissive texture for all buildings, which is faded in at night to provide
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illusion of lit windows. Same texture coordinates and format at building-texture above.
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building-range-m: Range at which all buildings are visible. Beyond this point fewer and fewer
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buildings are rendered, with no buildings rendered at 2*building-range-m (default 10000)
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