notes:comporg:spring2025:projects:mtb1
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| Both sides previous revisionPrevious revisionNext revision | Previous revision | ||
| notes:comporg:spring2025:projects:mtb1 [2025/02/19 22:36] – [Selecting joystick] bdildine | notes:comporg:spring2025:projects:mtb1 [2025/02/20 03:33] (current) – [How to check if our sprite has reached a bound] tkastne1 | ||
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| Line 54: | Line 54: | ||
| Selecting a joystick is very similar to the C process and only takes one command. | Selecting a joystick is very similar to the C process and only takes one command. | ||
| In C, we use: | In C, we use: | ||
| - | '' | + | < |
| + | select_gamepad( gamepadID ); | ||
| + | </ | ||
| Where gamepadID is the value of the gamepad you wish to select. | Where gamepadID is the value of the gamepad you wish to select. | ||
| In assembly we use: | In assembly we use: | ||
| - | '' | + | < |
| + | out INP_SelectedGamepad, | ||
| + | </ | ||
| Where again, gamepadID is the gamepad we wish the use. | Where again, gamepadID is the gamepad we wish the use. | ||
| ====Reading joystick value==== | ====Reading joystick value==== | ||
| + | Reading the joystick values is also similar to the C version, the C version is the following: | ||
| + | < | ||
| + | variableName = gamepad_left(); | ||
| + | </ | ||
| + | Where variableName is a integer variable | ||
| + | In assembly we use registers instead of variables to store the returned value | ||
| + | < | ||
| + | in R0, INP_GamepadLeft | ||
| + | </ | ||
| + | Reading the other directions can be done by using up/ | ||
| ====translating read joystick value into X and Y==== | ====translating read joystick value into X and Y==== | ||
| + | The value returned by the gamepad is the number of frames it has been in that state | ||
| + | This value can be converted into a boolean with ige: | ||
| + | < | ||
| + | ige R0, 0 | ||
| + | </ | ||
| + | Where R0 is a joystick direction value | ||
| + | |||
| + | After you have the boolean version, you can either use a conditional jump to a label that does whatever you want when a certain direction is pressed, or directly add/ | ||
| + | < | ||
| + | jt R0 _label | ||
| + | </ | ||
| + | or | ||
| + | < | ||
| + | iadd R1, R0 | ||
| + | </ | ||
| + | Where R1 is a x/y position | ||
| =====Playfield bounds checking===== | =====Playfield bounds checking===== | ||
| Line 71: | Line 101: | ||
| ====How to check if our sprite has reached a bound==== | ====How to check if our sprite has reached a bound==== | ||
| + | Checking the bounds of the screen can be done using greater than/less than instructions | ||
| + | Remember that instructions overwrite the register | ||
| + | < | ||
| + | mov R0, R1 | ||
| + | ilt R0, YMIN | ||
| + | jt R0, _upper_bound | ||
| + | </ | ||
| + | and | ||
| + | < | ||
| + | mov R0, R1 | ||
| + | igt R0, YMAX | ||
| + | jt R0, _lower_bound | ||
| + | </ | ||
| + | Where R1 is a the y position and YMIN/YMAX are the min and max bounds | ||
| ====How to limit our sprite from leaving the playfield==== | ====How to limit our sprite from leaving the playfield==== | ||
| ====How to cause our sprite to wrap-around on the playfield==== | ====How to cause our sprite to wrap-around on the playfield==== | ||
notes/comporg/spring2025/projects/mtb1.1740004589.txt.gz · Last modified: 2025/02/19 22:36 by bdildine
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