fly/flightgear
1
0
Fork 0
Code Activity

Start of documentation for effects

Browse source
This commit is contained in:
timoore 2009-07-15 23:16:41 +00:00 committed by Tim Moore
parent e2b21c1e0c
commit 122d7c92cc
1 changed files with 203 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

203
docs-mini/README.effects Normal file
View file

@ -0,0 +1,203 @@
<?xml version="1.0" encoding="utf-8">
<!--
An effect consists of parameters and techniques. The "parameters"
section of an effect is a tree of values that describe, abstractly,
the graphical appearence of objects that use the effect. Techniques
refer to these parameters and use them to set OpenGL state or to
set parameters for shader programs. Parameters can be declared to
have a dynamic variance, which means that if their value is changed
the corresponding value in the technique will be changed too.
A technique can contain a predicate that describes the OpenGL
functionality required to support the technique. The first
technique with a valid predicate in the list of techniques is used
to set up the graphics state of the effect. A technique with no
predicate is always assumed to be valid.
A technique can consist of several passes, which are run in
sequence.
One feature not fully illustrated in the sample below is that
effects can inherit from each other. The parent effect is listed in
the "inherits-from" form. The child effect's property tree is
overlaid over that of the parent. This means that effects that
inherit from the example "default effect" below could be very
short, listing just new parameters and adding nothing to the
techniques section; alternatively, a technique could be altered or
customized in a child, listing (for example) a different shader
program. Terrain materials work in this way: for each material type
in materials.xml an effect is created that inherits from a single
default terrain effect. The parameters section of the effect is
filled in using the ambient, diffuse, etc. fields of the material.
Material animations will be implemented by creating a new effect
that inherits from one in a model, overriding the parameters that
will be animated.
Ultimately all OpenGL state will be setable in a technique. These
attributes and modes are currently implemented:
lighting - true, false
shade-model - flat, smooth
cull-face - front, back, front-back
rendering-hint - (OSG) opaque, transparent
render-bin - children: bin-number, bin-name
material - children: ambient, ambient-front, ambient-back, diffuse,
diffuse-front, diffuse-back, specular, specular-front,
specular-back, emissive, emissive-front, emissive-back, shininess,
shininess-front, shininess-back, color-mode
blend - true, false
alpha-test - true, false
texture-unit -
unit
texture2d
image (file name)
filter
mag-filter
wrap-s
wrap-t
wrap-r
environment
mode
color
program
vertex-shader
fragment-shader
uniform
name
type - float, float-vec3, float-vec4, sampler-1d, sampler-2d,
sampler-3d
polygon-mode
front - fill, line, point
back - fill, line, point
-->
<PropertyList>
<effect>
<name>city</name>
<!-- <inherits-from>another-effect</inherits-from> -->
<parameters>
<material>
<ambient type="vec4d">
0.0 0.0 0.0 1.0
</ambient>
<diffuse type="vec4d">
.5 .5 .5 1.0
</diffuse>
<specular type="vec4d">
0.3 0.3 0.3 1.0
</specular>
<emissive type="vec4d" variance="dynamic">
0.0 0.0 0.0 1.0
</emissive>
<shininess>1.2</shininess>
</material>
<texture n="0">
<texture2d>
<image>city.png</image>
<filter>linear-mipmap-linear</filter>
<!-- also repeat -->
<wrap-s>clamp</wrap-s>
<wrap-t>clamp-to-edge</wrap-t>
<!--
<wrap-r>clamp-to-border</wrap-r>
-->
<!-- float, signed-integer, integer -->
<internal-format>normalized</internal-format>
</texture2d>
</texture>
<texture n="1">
<texture2d>
<image>detail.png</image>
<filter>linear-mipmap-linear</filter>
<!-- also repeat -->
<wrap-s>clamp</wrap-s>
<wrap-t>clamp-to-edge</wrap-t>
<!--
<wrap-r>clamp-to-border</wrap-r>
-->
<!-- float, signed-integer, integer -->
<internal-format>normalized</internal-format>
</texture2d>
</texture>
<bump-height type="double">.05</bump-height>
<pattern-rotation type="vec4d">0 0 1 1.5708</pattern-rotation>
</parameters>
<technique>
<predicate>
<!-- This is the general way to test for shader support -->
<or>
<less-equal>
<value type="float">2.0</value>
<glversion/>
</less-equal>
<and>
<extension-supported>GL_ARB_shader_objects</extension-supported>
<extension-supported>GL_ARB_shading_language_100</extension-supported>
<extension-supported>GL_ARB_vertex_shader</extension-supported>
<extension-supported>GL_ARB_fragment_shader</extension-supported>
</and>
</or>
</predicate>
<pass>
<lighting>true</lighting>
<material>
<ambient><use>material/ambient</use></ambient>
<diffuse><use>material/diffuse</use></diffuse>
<specular><use>material/specular</use></specular>
<shininess><use>material/shininess</use></shininess>
</material>
<texture-unit>
<texture2d><use>texture[0]/texture2d</use></texture2d>
</texture-unit>
<texture-unit>
<texture2d><use>texture[1]/texture2d</use></texture2d>
</texture-unit>
<uniform>
<name>bumpHeight</name>
<type>float</type>
<use>bump-height</use>
</uniform>
<uniform>
<name>patternRotation</name>
<type>float-vec4</type>
<use>pattern-rotation</use>
</uniform>
<uniform>
<name>baseTexture</name>
<type>sampler-2d</type>
<value>0</value>
</uniform>
<uniform>
<name>detailTexture</name>
<type>sampler-2d</type>
<value>1</value>
</uniform>
<shader-program>
<!-- These two vertex shaders are linked together -->
<vertex-shader>
"Shaders/util.vert"
</vertex-shader>
<vertex-shader>
"Shaders/foo.vert"
</vertex-shader>
<fragment-shader>
"Shaders/foo.frag"
</fragment-shader>
</shader-program>
</pass>
</technique>
<!-- This technique is always valid -->
<technique>
<pass>
<lighting>true</lighting>
<material>
<ambient><use>material/ambient</use></ambient>
<diffuse><use>material/diffuse</use></diffuse>
<specular><use>material/specular</use></specular>
</material>
<texture-unit>
<texture2d><use>texture[0]/texture2d</use></texture2d>
</texture-unit>
</pass>
</technique>
</effect>
</PropertyList>