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1 | (some) OMAP hardware support for SDL |
2 | by notaz (notasas@gmail.com) |
3 | |
4 | |
5 | About |
6 | ----- |
7 | |
8 | This is a quick SDL driver to make use of some OMAP features, namely double |
9 | buffering and hardware scaler. |
10 | |
11 | The backstory of this is that SDL on Pandora console was suffering from tearing |
12 | and stuttering problems because SDL default x11 driver doesn't work that well |
13 | there. Almost 6 months have passed after pandora's release, no improved |
14 | SDL versions appeared (not blaming anyone here, pandora's availability was low |
15 | and there where were several SDL improvement in the works though). This |
16 | encouraged me to create this quick version until something better appears |
17 | (if ever). |
18 | |
19 | Although this was created for pandora, there is nothing preventing this to work |
20 | on other OMAP platforms as well (well, nothing intentional at least). |
21 | |
22 | |
23 | Usage / environment |
24 | ------------------- |
25 | |
26 | To enable this driver, SDL_VIDEODRIVER environment variable must be set to |
27 | "omapdss". It can be set by calling setenv() in the code, but it's better to |
28 | just set it in launcher script so that it can be changed easily without |
29 | recompiling as needed: |
30 | --- |
31 | #!/bin/sh |
32 | export SDL_VIDEODRIVER=omapdss |
33 | ./your_program_here |
34 | --- |
35 | |
36 | Other environment variables: |
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37 | |
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38 | SDL_OMAP_LAYER_SIZE: |
39 | Output layer size. Regardless what you set with SDL_SetVideoMode(), output |
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40 | will be scaled to this size using hardware with zero processing cost. |
41 | Note: scaling amount range is limited to roughly 1/4x-8x. The exact range |
42 | depends on various factors like version of the driver or OMAP hardware itself. |
43 | Valid values: |
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44 | "WxH", for example "640x480" |
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45 | "fullscreen" to cover whole screen. |
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46 | |
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47 | SDL_OMAP_BORDER_CUT: |
48 | This can be used to move parts of SDL surface out of screen, in other |
49 | words cut borders and zoom in. Format: <left>,<right>,<top>,<bottom> |
50 | For example, "0,0,16,0" would hide top 16 lines offscreen, making 17th |
51 | (16th if you count from 0) line the first visible. |
52 | Note: like for layer size ranges are limited. |
53 | |
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54 | SDL_OMAP_VSYNC: |
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55 | Enables waiting for vertical sync on SDL_Flip() calls. |
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56 | Set to "1" to enable, "0" to disable. |
57 | |
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58 | SDL_OMAP_DEFAULT_MODE: |
59 | If the app doesn't specify resolution in SDL_SetVideoMode(), then use this. |
60 | Should be specified in "WxH" format, for example "640x480". |
61 | |
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62 | SDL_OMAP_FORCE_DOUBLEBUF: |
63 | This can force double buffering to on, which can help to eliminate tearing. |
64 | Note that if app isn't updating whole buffer each frame, it will glitch. |
65 | This is the same as specifying SDL_DOUBLEBUF to SDL_SetVideoMode. |
66 | |
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67 | SDL_OMAP_NO_TS_TRANSLATE: |
68 | Disable automatic touchscreen screen -> layer coordinate translation, |
69 | return real screen coordinates. |
70 | |
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71 | |
72 | Config file |
73 | ----------- |
74 | |
75 | Optionally a file named "omapsdl.cfg" can be created in the game's working |
76 | directory. It has lower priority than environment variables, and has these |
77 | options (only when omapdss driver is active): |
78 | |
79 | # same as SDL_OMAP_VSYNC |
80 | force_vsync = 1/0 |
81 | |
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82 | # same as SDL_OMAP_FORCE_DOUBLEBUF |
83 | force_doublebuf = 1/0 |
84 | |
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85 | # same as SDL_OMAP_NO_TS_TRANSLATE |
86 | no_ts_translate = 1/0 |
87 | |
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88 | # can be used to bind a key to SDL keysym, good for quick ports. |
89 | # Example: |
90 | # bind ev_home = sdlk_space |
91 | bind ev_<evdev_key> = <sdl_key> |
92 | |
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93 | |
94 | Source |
95 | ------ |
96 | |
97 | Available at git://notaz.gp2x.de/~notaz/sdl_omap.git |
98 | |