Unit al5opengl

Returns the OpenGL or OpenGL ES version number of the client (the computer the program is running on), for the current display. "1.0" is returned as $01000000, "1.2.1" is returned as $01020100, and "1.2.2" as $01020200 ,etc.

A valid OpenGL context must exist for this function to work, which means you may not call it before al_create_display.

See also

al_get_opengl_variant

Returns the variant or type of OpenGL used on the running platform.

This function is a helper to determine whether an OpenGL extension is available on the given display or not.

Example

packedpixels := al_have_opengl_extension ('GL_EXT_packed_pixels');

If packedpixels is True then you can safely use the constants related to the packed pixels extension.

Returns

True if the extension is available; False otherwise.

See also

al_get_opengl_proc_address

Helper to get the address of an OpenGL symbol.

Helper to get the address of an OpenGL symbol.

Example

How to get the function glMultiTexCoord3fARB that comes with ARB's Multitexture extension:

TYPE
{ Define the type of the function. }
  MULTI_TEX_FUNC: PROCEDURE (a: GLenum; b, c, d: GLfloat); CDECL;
VAR
{ Declare the function pointer. }
  glMultiTexCoord3fARB: MULTI_TEX_FUNC;
BEGIN
{ get the address of the function. }
  glMultiTexCoord3fARB := MULTI_TEX_FUNC (al_get_opengl_proc_address ('glMultiTexCoord3fARB'))
END;

If glMultiTexCoord3fARB is not Nil then it can be used as if it has been defined in the OpenGL core library.

Parameters

name

The name of the symbol you want to link to.

Returns

A pointer to the symbol if available or Nil otherwise.

See also

al_have_opengl_extension

This function is a helper to determine whether an OpenGL extension is available on the given display or not.

Returns the OpenGL texture id internally used by the given bitmap if it uses one, else 0.

Example

Bitmap := al_load_bitmap ('my_texture.png');
Texture := al_get_opengl_texture (Bitmap);
IF texture <> NIL THEN glBindTexture (GL_TEXTURE_2D, Texture);

Explicitly frees an OpenGL FBO created for a bitmap, if it has one. Usually you do not need to worry about freeing FBOs, unless you use al_get_opengl_fbo.

See also

al_get_opengl_fbo

Returns the OpenGL FBO id internally used by the given bitmap if it uses one, otherwise returns zero.

al_set_target_bitmap

This function selects the bitmap to which all subsequent drawing operations in the calling thread will draw to.

Returns the OpenGL FBO id internally used by the given bitmap if it uses one, otherwise returns zero. No attempt will be made to create an FBO if the bitmap is not owned by the current display.

The FBO returned by this function will only be freed when the bitmap is destroyed, or if you call al_remove_opengl_fbo on the bitmap.

Note: In Allegro 5.0.0 this function only returned an FBO which had previously been created by calling al_set_target_bitmap. It would not attempt to create an FBO itself. This has since been changed.

See also

al_remove_opengl_fbo

Explicitly frees an OpenGL FBO created for a bitmap, if it has one.

al_set_target_bitmap

This function selects the bitmap to which all subsequent drawing operations in the calling thread will draw to.

Retrieves the size of the texture used for the bitmap. This can be different from the bitmap size if OpenGL only supports power-of-two sizes or if it is a sub-bitmap.

Returns

True on success, False on failure. Zero width and height are returned if the bitmap is not an OpenGL bitmap.

See also

al_get_opengl_texture_position

Returns the u/v coordinates for the top/left corner of the bitmap within the used texture, in pixels.

Returns the u/v coordinates for the top/left corner of the bitmap within the used texture, in pixels.

See also

al_get_opengl_texture_size

Retrieves the size of the texture used for the bitmap.

Returns the OpenGL program object associated with this shader, if the platform is ALLEGRO_SHADER_GLSL. Otherwise, returns 0.

Make the OpenGL context associated with the given display current for the calling thread. If there is a current target bitmap which belongs to a different OpenGL context, the target bitmap will be changed to Nil.

Normally you do not need to use this function, as the context will be made current when you call al_set_target_bitmap or al_set_target_backbuffer. You might need it if you created an OpenGL "forward compatible" context. Then al_get_backbuffer only returns Nil, so it would not work to pass that to al_set_target_bitmap.

Returns the variant or type of OpenGL used on the running platform. This function can be called before creating a display or setting properties for new displays. Possible values are:

ALLEGRO_DESKTOP_OPENGL

Regular OpenGL as seen on desktop/laptop computers.

ALLEGRO_OPENGL_ES

Trimmed down version of OpenGL used on many small consumer electronic devices such as handheld (and sometimes full size) consoles.

See also

al_get_opengl_version

Returns the OpenGL or OpenGL ES version number of the client (the computer the program is running on), for the current display.