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Docs/README.effects
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@ -19,7 +19,7 @@ parameters for shader programs. The names of properties in the
parameter section can be whatever the effects author chooses, although parameter section can be whatever the effects author chooses, although
some standard parameters are set by FlightGear itself. On the other some standard parameters are set by FlightGear itself. On the other
hand, the properties in the techniques section are all defined by the hand, the properties in the techniques section are all defined by the
FlightGear. FlightGear.
Techniques Techniques
---------- ----------
@ -35,7 +35,7 @@ and, or, equal, less, less-equal
glversion - returns the version number of OpenGL glversion - returns the version number of OpenGL
extension-supported - returns true if an OpenGL extension is supported extension-supported - returns true if an OpenGL extension is supported
property - returns the boolean value of a property property - returns the boolean value of a property
float-property - returns the float value of a property, useful inside equal, less float-property - returns the float value of a property, useful inside equal, less
or less-equal nodes or less-equal nodes
shader-language - returns the version of GLSL supported, or 0 if there is none. shader-language - returns the version of GLSL supported, or 0 if there is none.
@ -50,7 +50,7 @@ The proper way to test whether to enable a shader-based technique is:
</and> </and>
</predicate> </predicate>
There is also a property set by the user to indicate what is the level There is also a property set by the user to indicate what is the level
of quality desired. This level of quality can be checked in the predicate of quality desired. This level of quality can be checked in the predicate
like this : like this :
<predicate> <predicate>
@ -63,7 +63,7 @@ like this :
<!-- other predicate conditions --> <!-- other predicate conditions -->
</and> </and>
</predicate> </predicate>
The range of /sim/rendering/quality-level is [0..5] The range of /sim/rendering/quality-level is [0..5]
* 2.0 is the threshold for relief mapping effects, * 2.0 is the threshold for relief mapping effects,
* 4.0 is the threshold for geometry shader usage. * 4.0 is the threshold for geometry shader usage.
@ -143,8 +143,8 @@ The following attributes are currently implemented in techiques:
alpha-test - children: active, comparison, reference alpha-test - children: active, comparison, reference
Valid values for comparision: Valid values for comparision:
never, less, equal, lequal, greater, notequal, gequal, never, less, equal, lequal, greater, notequal, gequal,
always always
alpha-to-coverage - true, false alpha-to-coverage - true, false
blend - children: active, source, destination, source-rgb, blend - children: active, source, destination, source-rgb,
@ -176,7 +176,7 @@ program
attribute attribute
geometry-vertices-out - integer, max number of vertices emitted by geometry geometry-vertices-out - integer, max number of vertices emitted by geometry
shader shader
geometry-input-type - points, lines, lines-adjacency, triangles, geometry-input-type - points, lines, lines-adjacency, triangles,
triangles-adjacency triangles-adjacency
geometry-output-type - points, line-strip, triangle-strip geometry-output-type - points, line-strip, triangle-strip
@ -188,21 +188,45 @@ shade-model - flat, smooth
texture-unit - has several child properties: texture-unit - has several child properties:
unit - The number of an OpenGL texture unit unit - The number of an OpenGL texture unit
type - This is either an OpenGL texture type or the name of a point-sprite - true, false - Whether this should rendered as a point-sprite
type - This is either an OpenGL texture type or the name of a
builtin texture. Currently supported OpenGL types are 1d, 2d, builtin texture. Currently supported OpenGL types are 1d, 2d,
3d which have the following common parameters: 3d which have the following common parameters:
image (file name) image (file name)
filter filter - nearest, linear, [nearest|linear]-mipmap-[nearest|linear]
mag-filter mag-filter - nearest, linear, [nearest|linear]-mipmap-[nearest|linear]
wrap-s wrap-s - clamp, clamp-to-border, clamp-to-edge, mirror, repeat
wrap-t wrap-t - clamp, clamp-to-border, clamp-to-edge, mirror, repeat
wrap-r wrap-r - clamp, clamp-to-border, clamp-to-edge, mirror, repeat
mipmap-control - control the mipmap on a per-channel basis. Children:
function-r - auto, average, sum, product, min, max
function-g - auto, average, sum, product, min, max
function-b - auto, average, sum, product, min, max
function-a - auto, average, sum, product, min, max
The following built-in types are supported: The following built-in types are supported:
white - 1 pixel white texture white - 1 pixel white texture
noise - a 3d noise texture noise - a 3d noise texture. (size parameter defines size of texture)
environment light-sprite - a procedurally generated sprite suitable for point lights
mode cubemap - build a cube-map. Children:
color images - build from 6 images. Children: [positive|negative]-[x|y|z]
image - build from a single cross-image
environment
mode - add, blend, decal, modulate, replace
color
texenv-combine
combine-[rgb|alpha] - replace, modulate, add, add-signed, interpolate, subtract, dot3-rgb, dot3-rgba
source[0|1|2]-[rgb|alpha] - constant, primary_color, previous, texture, texture[0-7]
operand[0|1|2]-[rgb|alpha] -src-color, one-minus-src-color, src-alpha, one-minus-src-alpha
scale-[rgb|alpha]
constant-color
texgen
mode - object-linear, eye-linear, sphere-map, normal-map, reflection-map
planes - s, t, r, q
uniform uniform
name name
type - float, float-vec3, float-vec4, sampler-1d, sampler-2d, type - float, float-vec3, float-vec4, sampler-1d, sampler-2d,
@ -240,10 +264,10 @@ parameters section.
Generate Generate
-------- --------
Often shader effects need tangent vectors to work properly. These Often shader effects need tangent vectors to work properly. These
tangent vectors, usually called tangent and binormal, are computed tangent vectors, usually called tangent and binormal, are computed
on the CPU and given to the shader as vertex attributes. These on the CPU and given to the shader as vertex attributes. These
vectors are computed on demand on the geometry using the effect if vectors are computed on demand on the geometry using the effect if
the 'generate' clause is present in the effect file. Exemple : the 'generate' clause is present in the effect file. Exemple :
<generate> <generate>
@ -253,12 +277,12 @@ the 'generate' clause is present in the effect file. Exemple :
</generate> </generate>
Valid subnodes of 'generate' are 'tangent', 'binormal' or 'normal'. Valid subnodes of 'generate' are 'tangent', 'binormal' or 'normal'.
The integer value of these subnode is the index of the attribute The integer value of these subnode is the index of the attribute
that will hold the value of the vec3 vector. that will hold the value of the vec3 vector.
The generate clause is located under PropertyList in the xml file. The generate clause is located under PropertyList in the xml file.
In order to be available for the vertex shader, these data should In order to be available for the vertex shader, these data should
be bound to an attribute in the program clause, like this : be bound to an attribute in the program clause, like this :
<program> <program>
@ -273,9 +297,9 @@ be bound to an attribute in the program clause, like this :
</attribute> </attribute>
</program> </program>
attribute names are whatever the shader use. The index is the one attribute names are whatever the shader use. The index is the one
declared in the 'generate' clause. So because generate/tangent has declared in the 'generate' clause. So because generate/tangent has
value 6 and my_tangent_attribute has index 6, my_tangent_attribute value 6 and my_tangent_attribute has index 6, my_tangent_attribute
holds the tangent value for the vertex. holds the tangent value for the vertex.
Default Effects in Terrain Materials and Models Default Effects in Terrain Materials and Models
@ -297,7 +321,7 @@ with parameters extracted from OSG objects; this effect inherits, by
default, from Effects/model-default.eff. A larger set of parameters is default, from Effects/model-default.eff. A larger set of parameters is
created for model effects than for terrain because there is more created for model effects than for terrain because there is more
variation possible from the OSG model loaders than from the terrain variation possible from the OSG model loaders than from the terrain
system. The parameters created are: system. The parameters created are:
* material active, ambient, diffuse, specular, emissive, * material active, ambient, diffuse, specular, emissive,
shininess, color mode shininess, color mode
@ -343,7 +367,7 @@ apply. The effect does not need the file extension.
NOTE: NOTE:
Chrome, although now implemented as an effect, still retains the old method of Chrome, although now implemented as an effect, still retains the old method of
application: application:
<animation> <animation>