[rcore] Fix #4405

[asdqwe]

All credits to @dmg46664 for finding this issue (#4405, ref) and pointing the solution. Great catch!

Summary: At the moment a mininum value of 0.1f is being applied on all gamepad axis at all times on all platforms. Since the deadzone depends on each specific gamepad, it's indeed something that should be exposed to the end-user (e.g.: the player playing the game) be able to adjust to his case at runtime. This PR adds deadzone to CORE.Input.Gamepad and exposes SetGamepadDeadzone() to set that value. It also allows the dev-user to zero it and handle the deadzone himself.

This PR can be tested with:

#include "raylib.h"
int main(void) {
    InitWindow(400, 300, "test");
    SetTargetFPS(60);

    // Control the deadzone here:
    SetGamepadDeadzone(0.001f);

    while (!WindowShouldClose()) {

        // Get axis values:
        float lax = GetGamepadAxisMovement(0, GAMEPAD_AXIS_LEFT_X);
        float lay = GetGamepadAxisMovement(0, GAMEPAD_AXIS_LEFT_Y);
        float rax = GetGamepadAxisMovement(0, GAMEPAD_AXIS_RIGHT_X);
        float ray = GetGamepadAxisMovement(0, GAMEPAD_AXIS_RIGHT_Y);

        BeginDrawing();
        ClearBackground(RAYWHITE);

        DrawCircle(100, 80, 50, LIGHTGRAY);
        DrawCircle(100+(int)(lax*50), 80+(int)(lay*50), 5, RED);
        DrawText(TextFormat("LAX %f", lax), 30, 140, 20, BLACK);
        DrawText(TextFormat("LAY %f", lay), 30, 160, 20, BLACK);

        DrawCircle(300, 80, 50, LIGHTGRAY);
        DrawCircle(300+(int)(rax*50), 80+(int)(ray*50), 5, BLUE);
        DrawText(TextFormat("RAX %f", rax), 230, 140, 20, BLACK);
        DrawText(TextFormat("RAY %f", ray), 230, 160, 20, BLACK);

        EndDrawing();
    }
    CloseWindow();
    return 0;
}

And devs can implement individual deadzones like this:

#include "raylib.h"
int main(void) {
    InitWindow(400, 300, "test");
    SetTargetFPS(60);

    // Set axis deadzones:
    SetGamepadDeadzone(0.0f);
    int dz = 0;
    float laxdz = 0.5f;
    float laydz = 0.5f;
    float raxdz = 0.5f;
    float raydz = 0.5f;

    while (!WindowShouldClose()) {

        // Toggle deadzone: [gamepad button A]
        if (IsGamepadButtonPressed(0, GAMEPAD_BUTTON_RIGHT_FACE_DOWN)) { dz = !dz; }

        // Get axis values:
        float lax = GetGamepadAxisMovement(0, GAMEPAD_AXIS_LEFT_X);
        float lay = GetGamepadAxisMovement(0, GAMEPAD_AXIS_LEFT_Y);
        float rax = GetGamepadAxisMovement(0, GAMEPAD_AXIS_RIGHT_X);
        float ray = GetGamepadAxisMovement(0, GAMEPAD_AXIS_RIGHT_Y);

        // Calculate deadzones:
        if (dz) {
            if (lax > -laxdz && lax < laxdz) { lax = 0.0f; }
            if (lay > -laydz && lay < laydz) { lay = 0.0f; }
            if (rax > -raxdz && rax < raxdz) { rax = 0.0f; }
            if (ray > -raydz && ray < raydz) { ray = 0.0f; }
        }

        BeginDrawing();
        ClearBackground(RAYWHITE);

        DrawCircle(100, 80, 50, LIGHTGRAY);
        if (dz) { DrawEllipse(100, 80, 50*laxdz, 50*laydz, BLACK); }
        DrawCircle(100+(int)(lax*50), 80+(int)(lay*50), 5, RED);
        DrawText(TextFormat("LAX %f", lax), 30, 140, 20, BLACK);
        DrawText(TextFormat("LAY %f", lay), 30, 160, 20, BLACK);

        DrawCircle(300, 80, 50, LIGHTGRAY);
        if (dz) { DrawEllipse(300, 80, 50*raxdz, 50*raydz, BLACK); }
        DrawCircle(300+(int)(rax*50), 80+(int)(ray*50), 5, BLUE);
        DrawText(TextFormat("RAX %f", rax), 230, 140, 20, BLACK);
        DrawText(TextFormat("RAY %f", ray), 230, 160, 20, BLACK);

        DrawText("Toggle deadzone:\n[gamepad button A]", 30, 220, 20, BLACK);
        EndDrawing();
    }
    CloseWindow();
    return 0;
}

Fixes #4405.

[raysan5]

@asdqwe Is it really required to add a new function to raylib API? I'd prefer to avoid that if it could be managed on user side.

Afaik, it can be checked and scaled at user side, no need for a new internal global and a new function.

[raysan5]

@asdqwe thanks for the review!

[raysan5]

@asdqwe that would be great! thanks! 👍🙂