Native Development

[rus_phantom]

   Hello. I tried to render on screen PNG image with alpha channel, using bbutil_load_texture function for load image and that code

glEnable(GL_TEXTURE_2D);

glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);

glVertexPointer(2, GL_FLOAT, 0, m_vertices);
glTexCoordPointer(2, GL_FLOAT, 0, m_tex_coord);
glBindTexture(GL_TEXTURE_2D, m_texture);

glColor4f(m_color.r, m_color.g, m_color.b, 1.0f);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glDisableClientState(GL_VERTEX_ARRAY);
glDisable(GL_TEXTURE_2D);

to render it on my playbook. But its looks like that OpenGL doesn't look at alpha channel at all - my image rendering without transparency. That is image, with I want to render: ClickMe

That is a screenshot of what I got on the screen: ClickMe

Thanks

[MikePembo951]

correct me if im wrong but shouldnt you need GL blending turned on?

e.g.

glEnable(GL_BLEND);

glBlendFunct(__Source blending__, _Destination blending_);

//Draw stuff here

then once finished:

glDisable(GL_BLEND);

replace source and destination blending with the settings you want.

Look here:

http://www.khronos.org/opengles/sdk/docs/man/xhtml/glBlendFunc.xml

[MikePembo951]

try:

glBlendFunct(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

[BGmot]

How do you create native window on top of which you have your OpenGL? what format do you use?

[MikePembo951]

I'm confused,  BGmot could you rephrase the question?

[BGmot]

First you create native window

screen_create_window()

the set up transparency

int transparency = SCREEN_TRANSPARENCY_SOURCE_OVER;

screen_set_window_property_iv(screen_win_gles, SCREEN_PROPERTY_TRANSPARENCY, &transparency);

Then format I was talking above:

int format = SCREEN_FORMAT_RGBA8888;

screen_set_window_property_iv(screen_win_gles, SCREEN_PROPERTY_FORMAT, &format);

... some more settings here..

and finally 'attach' EGL surface to this window by calling eglCreateWindowSurface()

So what I meant was format and transparency settings are important if you want to acheive OpenGL window drawing transparency (at least if it placed on top of other native windows).