Hello all,
I am currently working on a small project for which I have decided to use
the Clutter and Cogl APIs. I am attempting to implement a custom Clutter
Actor and am managing the drawing of this Actor using Cogl. I am having a
problem, however, with the transparency of items drawn using "pure" COGL:
changing the alpha value has no effect, and the result is 100% opaque.
Here are the relevant pieces of code:
// title area
{
cd[i++] = ColorManager::BORDER_LIGHT.get_red() / ColorManager::MAX_RGBA_VAL;
cd[i++] = ColorManager::BORDER_LIGHT.get_green() /
ColorManager::MAX_RGBA_VAL;
cd[i++] = ColorManager::BORDER_LIGHT.get_blue() /
ColorManager::MAX_RGBA_VAL;
cd[i++] = ColorManager::BORDER_LIGHT.get_alpha() /
ColorManager::MAX_RGBA_VAL;
cd[i++] = ColorManager::BORDER_LIGHT.get_red() /
ColorManager::MAX_RGBA_VAL;
cd[i++] = ColorManager::BORDER_LIGHT.get_green() /
ColorManager::MAX_RGBA_VAL;
cd[i++] = ColorManager::BORDER_LIGHT.get_blue() /
ColorManager::MAX_RGBA_VAL;
cd[i++] = 0.0;
}
cogl_vertex_buffer_add(vertex_data, "gl_Vertex", 2,
COGL_ATTRIBUTE_TYPE_FLOAT, FALSE, 0, vd);
cogl_vertex_buffer_add(vertex_data, "gl_Color", 4,
COGL_ATTRIBUTE_TYPE_FLOAT, FALSE, 0, cd);
cogl_vertex_buffer_submit(vertex_data);
and later on...
cogl_push_matrix();
{
cogl_scale((_width )/(I_SIZE) , 1.0, 1.0);
cogl_vertex_buffer_draw(vertex_data, COGL_VERTICES_MODE_LINE_STRIP, 12, 2);
}
cogl_pop_matrix();
Note that I have also tried enabling and disabling the stage feature that
forces it to honor Actor transparency:
stage->set_use_alpha(true); // or false
This changes nothing.
I have done a fair amount of search, but to no avail. If anyone has any
idea why setting the alpha channel to 0.0 has no effect, I would greatly
appreciate it.
Regards,
Andy
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