Changes between Version 2 and Version 3 of MaterialSystem

Timestamp:

Apr 15, 2012, 5:04:38 PM (12 years ago)

Author:

Philip Taylor

Comment:

material alternatives

MaterialSystem

@@ -21 +21 @@
  * '''Shader effects''' control which shader technique to use in each different context, depending on rendering mode, hardware capabilities, user-selected graphics options, etc.
 
+== Conditionals ==
+
+Various XML files can contain conditionals, which are typically attributes of the form `if="..."`. These are C-preprocessor-style boolean expressions that can use the current set of defines, e.g.:
+{{{
+<alternative ... if="CFG_FORCE_ALPHATEST"/>
+<require context="MODE_SHADOWCAST || MODE_SILHOUETTEOCCLUDER"/>
+<whatever if="(FOO || !(BAR && BAZ)) && QUX > 100"/>
+}}}
+
 == Materials ==
 
@@ -27 +36 @@
 <?xml version="1.0" encoding="utf-8"?>
 <material>
+    <alternative material="alphatest_spec.xml" if="CFG_FORCE_ALPHATEST"/>
     <shader effect="model_transparent"/>
     <alpha_blending/>
@@ -36 +46 @@
 }}}
 Materials can contain:
- * `<shader effect="..."/>` - refers to one of the [source:ps/trunk/binaries/data/mods/public/shaders/effects effect XML files].
- * `<alpha_blending/>` - required if using a shader effect that uses alpha-blending. (This causes the engine to render the model twice, in `ALPHABLEND_PASS_OPAQUE` and `ALPHABLEND_PASS_BLEND` passes, to get correct blending relative to transparent water.)
- * `<define name="..." value="..."/>` - specifies a name/value define that is used when loading the shader. The value is typically `"1"` to enable an effect.
- * `<uniform name="..." value="..."/>` - specifies a uniform value that is used when rendering models using this material. The value is between 1 and 4 space-separated decimal numbers, e.g. `value="16"` or `value="1.0 1.0 0.0 0.5"`.
+ * (rarely used) `<alternative material="..." if="..."/>` - if the conditional expression is true, then this material will be replaced by the given alternative. This can be useful so e.g. alpha-blended materials can get replaced with alpha-tested materials depending on some configuration.
+ * (required) `<shader effect="..."/>` - refers to one of the [source:ps/trunk/binaries/data/mods/public/shaders/effects effect XML files].
+ * (rarely used) `<alpha_blending/>` - required if using a shader effect that uses alpha-blending. (This causes the engine to render the model twice, in `ALPHABLEND_PASS_OPAQUE` and `ALPHABLEND_PASS_BLEND` passes, to get correct blending relative to transparent water.)
+ * (zero or more times) `<define name="..." value="..."/>` - specifies a name/value define that is used when loading the shader. The value is typically `"1"` to enable an effect.
+ * (zero or more times) `<uniform name="..." value="..."/>` - specifies a uniform value that is used when rendering models using this material. The value is between 1 and 4 space-separated decimal numbers, e.g. `value="16"` or `value="1.0 1.0 0.0 0.5"`.
 
 == Defines ==