[core] Some degrees issues on swipe gestures for web.

[ghost]

• I tested it on latest raylib version from master branch.
• I checked there is no similar issue already reported.
• My code has no errors or misuse of raylib.

Issue description

Upon taking a closer look at the swipe gestures handling, I noticed three issues:

1. It's apparently missing 30° on GESTURE_SWIPE_DOWN at rgestures.h#L317 to complete the 360°;
2. The GESTURE_SWIPE_RIGHT range is 60° (0+30=30, 360-30=330), but the GESTURE_SWIPE_LEFT range is 90° (180-60=120,180+30=210);
3. Albeit a rare occurance, the exact 30.0f, 120.0f (that should be 150.0f), 210.0f and 330.0f degrees are not being considered.

I believe these were the cause of some unexpected behavior I randomly experienced while testing the swipe gestures.

Proposed solution

The fix appears to be simple enough:

1. Change the 300 to 330 at rgestures.h#L317 to complete the 360°;
2. Change the 120 to 150 at rgestures.h#L315 and rgestures.h#L316 so both sides range is 60°;
3. Change the > to >= at rgestures.h#L315 and rgestures.h#L317 so those angles get caught if they happen.

Will send a PR with the proposed changes shortly.

Environment

Platform: Linux (x86_64)
Operating System: Linux Mint 21.1
OpenGL version: 3.1 Mesa 22.0.5
GPU: Intel HD Graphics 3000

Platform: Android
Operating System: Android 5.1.1
OpenGL version: OpenGL ES 1.1/2.0
GPU: Mali-400

Issue Screenshot

On Chrome (114.0.5735.106 64-bit) for Linux and on Chrome (95.0.4638.74) for Android:

Code Example

Minimal reproduction code to test the issue:

#include "raylib.h"

#if defined(PLATFORM_WEB)
    #include <emscripten/emscripten.h>
#endif

#include <stdio.h> // For snprintf().

int lastSwipe = GESTURE_NONE;
char lastAngleStr[20];

void Update(void) {
    const int gesture = GetGestureDetected();
    if (gesture == GESTURE_SWIPE_UP || gesture == GESTURE_SWIPE_RIGHT || gesture == GESTURE_SWIPE_LEFT || gesture == GESTURE_SWIPE_DOWN) { lastSwipe = gesture; }

    const float lastAngle = GetGestureDragAngle();
    snprintf(lastAngleStr, 20, "%f", lastAngle);

    BeginDrawing();
    ClearBackground(RAYWHITE);
    DrawRectangleLinesEx({0, 0, 400, 400}, 2.0f, BLACK);
    DrawText("Swipe on the screen.", 95, 360, 20, BLACK);
    DrawText("Last swipe:", 25, 20, 20, BLACK);
    DrawRectangle(70, 50, 20, 20, lastSwipe == GESTURE_SWIPE_UP    ? BLUE : LIGHTGRAY);
    DrawRectangle(50, 70, 20, 20, lastSwipe == GESTURE_SWIPE_LEFT  ? BLUE : LIGHTGRAY);
    DrawRectangle(90, 70, 20, 20, lastSwipe == GESTURE_SWIPE_RIGHT ? BLUE : LIGHTGRAY);
    DrawRectangle(70, 90, 20, 20, lastSwipe == GESTURE_SWIPE_DOWN  ? BLUE : LIGHTGRAY);
    DrawText("Swipe angle:", 250, 20, 20, BLACK);
    DrawText(lastAngleStr, 280, 50, 20, RED);
    DrawCircle( 200, 200, 100.0f, WHITE);
    DrawTriangle( {200, 200}, {248, 286}, {285, 251}, LIGHTGRAY);
    DrawLineEx( {50, 200}, {350, 200}, 2.0f, GREEN);
    DrawLineEx( {200, 50}, {200, 350}, 2.0f, GREEN);
    DrawLineEx( {115, 148}, {285, 251}, 2.0f, BLUE);
    DrawLineEx( {113, 249}, {285, 150}, 2.0f, BLUE);
    DrawText("30", 290, 130, 20, BLACK);
    DrawText("150", 80, 130, 20, BLACK);
    DrawText("210", 80, 250, 20, BLACK);
    DrawText("300", 245, 290, 20, BLACK);
    DrawText("330", 290, 250, 20, BLACK);
    EndDrawing();
}

int main(void) {
    InitWindow(400, 400, "Swipe Angle Test");
    #if defined(PLATFORM_WEB)
        emscripten_set_main_loop(Update, 0, 1);
    #else
        SetTargetFPS(60);
        while (!WindowShouldClose()) { Update(); }
    #endif
    CloseWindow();
    return 0;
}

[raysan5]

@ubkp Is the above code from the screenshot example? I think it could be moved to a raylib example to illustrate usage.

[ghost]

@raysan5 It is, although it's not very interactive (just printed the protractor to have some quick visual reference for the test). But I can make a better one.

I'm currently debugging GESTURE_DOUBLETAP not getting registered for Touch on Web. I'll include it (and the other gestures) so it's more complete.

[raysan5]

@ubkp ok, that would be great!

[ghost]

@raysan5 Sorry it took long, but I've finished the example. Just sent a PR with it.

Follow-up: Almost finishing sorting the GESTURE_DOUBLETAP. I should have the issues and fixes ready soon.

[raysan5]

@ubkp that's great! thank you very much for the improvement!