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| OpenGL clipping on sub bitmaps |
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Matthew Leverton
Supreme Loser
January 1999
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Perhaps related to this thread. It doesn't look like OpenGL honors clipping on sub bitmaps. Test program: 1int main()
2{
3 al_init();
4 al_init_primitives_addon();
5 al_set_new_display_flags(ALLEGRO_OPENGL);
6
7 ALLEGRO_DISPLAY *display = al_create_display(320, 240);
8 ALLEGRO_BITMAP *sub = al_create_sub_bitmap(al_get_backbuffer(display), 0, 0, 320, 240);
9
10 // clear to black
11 al_set_target_bitmap(sub);
12 al_clear_to_color(al_map_rgb(0,0,0));
13
14 // 64x64 clip with filled white rectangle
15 al_set_clipping_rectangle(0, 0, 64, 64);
16 al_draw_filled_rectangle(0, 0, 320, 240, al_map_rgb_f(1,1,1));
17
18 al_flip_display();
19
20 al_rest(5);
21 return 0;
22}
My initial test was clipping a sub bitmap of a regular (non backbuffer) bitmap; it had the same problem. Expected result (D3D): {"name":"602854","src":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/7\/d\/7d70960c3c746fc2e5e21cbe8ad29116.png","w":336,"h":278,"tn":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/7\/d\/7d70960c3c746fc2e5e21cbe8ad29116"} OpenGL: {"name":"602855","src":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/5\/e\/5ee6bba9dd6ca61d2d6945ec46283bb2.png","w":336,"h":278,"tn":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/5\/e\/5ee6bba9dd6ca61d2d6945ec46283bb2"} It works fine when the sub bitmap is removed. |
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Elias
Member #358
May 2000
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Can you try adding this to ogl_update_clipping_rectangle (in src/opengl/ogl_bitmap.c): if (bitmap->parent) ogl_bitmap = bitmap->parent; Basically the check if the bitmap is the opengl_target looks wrong to me as it would fail for sub-bitmaps. Can't test it myself right now. -- |
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Matthew Leverton
Supreme Loser
January 1999
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The attached patch seems to work. Index: ogl_bitmap.c
===================================================================
--- ogl_bitmap.c (revision 14083)
+++ ogl_bitmap.c (working copy)
@@ -530,6 +530,10 @@
ALLEGRO_DISPLAY *ogl_disp = al_get_current_display();
ALLEGRO_BITMAP_OGL *ogl_bitmap = (void *)bitmap;
+ if (bitmap->parent) {
+ ogl_bitmap = (ALLEGRO_BITMAP_OGL *)bitmap->parent;
+ }
+
if (ogl_disp->ogl_extras->opengl_target == ogl_bitmap) {
_al_ogl_setup_bitmap_clipping(bitmap);
}
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