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cogl-material: Don't map the shininess value to [0,1]

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In OpenGL the 'shininess' lighting parameter is floating point value
limited to the range 0.0→128.0. This number is used to affect the size
of the specular highlight. Cogl materials used to only accept a number
between 0.0 and 1.0 which then gets multiplied by 128.0 before sending
to GL. I think the assumption was that this is just a weird GL quirk
so we don't expose it. However the value is used as an exponent to
raise the attenuation to a power so there is no conceptual limit to
the value.

This removes the mapping and changes some of the documentation.

http://bugzilla.clutter-project.org/show_bug.cgi?id=2222
This commit is contained in:
Neil Roberts 2010-07-20 17:34:04 +01:00
parent 89286f6a47
commit 0ab6dc9db1
3 changed files with 10 additions and 9 deletions
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6
cogl/cogl-material-opengl.c
View File

@ -507,14 +507,12 @@ _cogl_material_flush_color_blend_alpha_depth_state (
CoglMaterialLightingState *lighting_state =
&authority->big_state->lighting_state;
/* FIXME - we only need to set these if lighting is enabled... */
GLfloat shininess = lighting_state->shininess * 128.0f;
GE (glMaterialfv (GL_FRONT_AND_BACK, GL_AMBIENT, lighting_state->ambient));
GE (glMaterialfv (GL_FRONT_AND_BACK, GL_DIFFUSE, lighting_state->diffuse));
GE (glMaterialfv (GL_FRONT_AND_BACK, GL_SPECULAR, lighting_state->specular));
GE (glMaterialfv (GL_FRONT_AND_BACK, GL_EMISSION, lighting_state->emission));
GE (glMaterialfv (GL_FRONT_AND_BACK, GL_SHININESS, &shininess));
GE (glMaterialfv (GL_FRONT_AND_BACK, GL_SHININESS,
&lighting_state->shininess));
}
if (materials_difference & COGL_MATERIAL_STATE_BLEND)

4
cogl/cogl-material.c
View File

@ -239,6 +239,8 @@ _cogl_material_init_default_material (void)
lighting_state->emission[2] = 0;
lighting_state->emission[3] = 1.0;
lighting_state->shininess = 0.0f;
/* Use the same defaults as the GL spec... */
alpha_state->alpha_func = COGL_MATERIAL_ALPHA_FUNC_ALWAYS;
alpha_state->alpha_func_reference = 0.0;
@ -3620,7 +3622,7 @@ cogl_material_set_shininess (CoglMaterial *material,
g_return_if_fail (cogl_is_material (material));
if (shininess < 0.0 || shininess > 1.0)
if (shininess < 0.0)
{
g_warning ("Out of range shininess %f supplied for material\n",
shininess);

9
cogl/cogl-material.h
View File

@ -387,11 +387,12 @@ cogl_material_get_specular (CoglMaterial *material,
/**
* cogl_material_set_shininess:
* @material: A #CoglMaterial object
* @shininess: The desired shininess; range: [0.0, 1.0]
* @shininess: The desired shininess; must be >= 0.0
*
* Sets the materials shininess, in the standard OpenGL lighting model,
* which determines how specular highlights are calculated. A higher
* @shininess will produce smaller brigher highlights.
* Sets the shininess of the material, in the standard OpenGL lighting
* model, which determines the size of the specular highlights. A
* higher @shininess will produce smaller highlights which makes the
* object appear more shiny.
*
* The default value is 0.0
*