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GObject ╰── GInitiallyUnowned ╰── ClutterActorMeta ╰── ClutterEffect ╰── ClutterOffscreenEffect ╰── ClutterShaderEffect
ClutterShaderEffect is a class that implements all the plumbing for creating ClutterEffects using GLSL shaders.
ClutterShaderEffect creates an offscreen buffer and then applies the GLSL shader (after checking whether the compilation and linking were successfull) to the buffer before painting it on screen.
ClutterShaderEffect is available since Clutter 1.4
Creating a sub-class of ClutterShaderEffect requires the
overriding of the ClutterOffscreenEffectClass.paint_target()
virtual
function from the ClutterOffscreenEffect class. It is also convenient
to implement the ClutterShaderEffectClass.get_static_shader_source()
virtual function in case you are planning to create more than one
instance of the effect.
The ClutterShaderEffectClass.get_static_shader_source()
function should return a copy of the shader source to use. This
function is only called once per subclass of ClutterShaderEffect
regardless of how many instances of the effect are created. The
source for the shader is typically stored in a static const
string which is returned from this function via
g_strdup()
.
The ClutterOffscreenEffectClass.paint_target()
should set the
shader's uniforms if any. This is done by calling
clutter_shader_effect_set_uniform_value()
or
clutter_shader_effect_set_uniform()
. The sub-class should then
chain up to the ClutterShaderEffect implementation.
The example below shows a typical implementation of the
ClutterShaderEffectClass.get_static_shader_source()
and
ClutterOffscreenEffectClass.paint_target()
virtual functions
for a ClutterShaderEffect subclass.
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static gchar * my_effect_get_static_shader_source (ClutterShaderEffect *effect) { // shader_source is set elsewhere return g_strdup (shader_source); } static gboolean my_effect_paint_target (ClutterOffscreenEffect *effect) { MyEffect *self = MY_EFFECT (effect); ClutterShaderEffect *shader = CLUTTER_SHADER_EFFECT (effect); ClutterEffectClass *parent_class; gfloat component_r, component_g, component_b; // the "tex" uniform is declared in the shader as: // // uniform int tex; // // and it is passed a constant value of 0 clutter_shader_effect_set_uniform (shader, "tex", G_TYPE_INT, 1, 0); // the "component" uniform is declared in the shader as: // // uniform vec3 component; // // and it's defined to contain the normalized components // of a #ClutterColor component_r = self->color.red / 255.0f; component_g = self->color.green / 255.0f; component_b = self->color.blue / 255.0f; clutter_shader_effect_set_uniform (shader, "component", G_TYPE_FLOAT, 3, component_r, component_g, component_b); // chain up to the parent's implementation parent_class = CLUTTER_OFFSCREEN_EFFECT_CLASS (my_effect_parent_class); return parent_class->paint_target (effect); } |
ClutterEffect *
clutter_shader_effect_new (ClutterShaderType shader_type
);
Creates a new ClutterShaderEffect, to be applied to an actor using
clutter_actor_add_effect()
.
The effect will be empty until clutter_shader_effect_set_shader_source()
is called.
shader_type |
the type of the shader, either |
Since: 1.8
void clutter_shader_effect_set_uniform (ClutterShaderEffect *effect
,const gchar *name
,GType gtype
,gsize n_values
,...
);
Sets a list of values as the payload for the uniform name
inside
the shader effect
The gtype
must be one of: G_TYPE_INT
, for 1 or more integer values;
G_TYPE_FLOAT
, for 1 or more floating point values;
CLUTTER_TYPE_SHADER_INT
, for a pointer to an array of integer values;
CLUTTER_TYPE_SHADER_FLOAT
, for a pointer to an array of floating point
values; and CLUTTER_TYPE_SHADER_MATRIX
, for a pointer to an array of
floating point values mapping a matrix
The number of values interepreted is defined by the n_value
argument, and by the gtype
argument. For instance, a uniform named
"sampler0" and containing a single integer value is set using:
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clutter_shader_effect_set_uniform (effect, "sampler0", G_TYPE_INT, 1, 0); |
While a uniform named "components" and containing a 3-elements vector of floating point values (a "vec3") can be set using:
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gfloat component_r, component_g, component_b; clutter_shader_effect_set_uniform (effect, "components", G_TYPE_FLOAT, 3, component_r, component_g, component_b); |
or can be set using:
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gfloat component_vec[3]; clutter_shader_effect_set_uniform (effect, "components", CLUTTER_TYPE_SHADER_FLOAT, 3, component_vec); |
Finally, a uniform named "map" and containing a matrix can be set using:
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clutter_shader_effect_set_uniform (effect, "map", CLUTTER_TYPE_SHADER_MATRIX, 1, cogl_matrix_get_array (&matrix)); |
effect |
||
name |
the name of the uniform to set |
|
gtype |
the type of the uniform to set |
|
n_values |
the number of values |
|
... |
a list of values |
Since: 1.4
void clutter_shader_effect_set_uniform_value (ClutterShaderEffect *effect
,const gchar *name
,const GValue *value
);
Sets value
as the payload for the uniform name
inside the shader
effect
The GType of the value
must be one of: G_TYPE_INT
, for a single
integer value; G_TYPE_FLOAT
, for a single floating point value;
CLUTTER_TYPE_SHADER_INT
, for an array of integer values;
CLUTTER_TYPE_SHADER_FLOAT
, for an array of floating point values;
and CLUTTER_TYPE_SHADER_MATRIX
, for a matrix of floating point
values. It also accepts G_TYPE_DOUBLE
for compatibility with other
languages than C.
effect |
||
name |
the name of the uniform to set |
|
value |
a GValue with the value of the uniform to set |
Since: 1.4
gboolean clutter_shader_effect_set_shader_source (ClutterShaderEffect *effect
,const gchar *source
);
Sets the source of the GLSL shader used by effect
This function should only be called by implementations of the ClutterShaderEffect class, and not by application code.
This function can only be called once; subsequent calls will yield no result.
Since: 1.4
CoglHandle
clutter_shader_effect_get_program (ClutterShaderEffect *effect
);
Retrieves a pointer to the program's handle
Since: 1.4
CoglHandle
clutter_shader_effect_get_shader (ClutterShaderEffect *effect
);
Retrieves a pointer to the shader's handle
Since: 1.4
struct ClutterShaderEffect;
The ClutterShaderEffect structure contains only private data and should be accessed using the provided API
Since: 1.4
struct ClutterShaderEffectClass { gchar * (* get_static_shader_source) (ClutterShaderEffect *effect); };
The ClutterShaderEffectClass structure contains only private data
Returns the GLSL source code to use for instances of this shader effect. Note that this function is only called once per subclass of ClutterShaderEffect regardless of how many instances are used. It is expected that subclasses will return a copy of a static string from this function. |
Since: 1.4
“shader-type”
property“shader-type” ClutterShaderType
The type of shader that is used by the effect. This property should be set by the constructor of ClutterShaderEffect sub-classes.
Owner: ClutterShaderEffect
Flags: Write / Construct Only
Default value: CLUTTER_FRAGMENT_SHADER
Since: 1.4