Make camera movement independant of framerate

[hanaxars]

Instead of moving camera with constant speed per frame, speed is multiplied with delta time before movement.

[hanaxars]

Camera can be tested with this small example. Try to lock/unlock fps while moving camera around, the movement stays constant and independent of ramerate.

#include "raylib.h"

int main(void)
{
    InitWindow(800, 450, "Camera Test");

    Camera camera = { 0 };
    camera.position = (Vector3){ 50.0f, 10.0f, 0.0f };
    camera.target = (Vector3){ 0.0f, 10.0f, 0.0f };
    camera.up = (Vector3){ 0.0f, 1.0f, 0.0f };
    camera.fovy = 45.0f;
    camera.projection = CAMERA_PERSPECTIVE;

    DisableCursor();
    SetTargetFPS(60);
    bool lockFPS = true;

    while (!WindowShouldClose())
    {
        UpdateCamera(&camera, CAMERA_FREE);

        if (IsKeyPressed(KEY_F))
        {
            lockFPS = !lockFPS;
            if (lockFPS)
                SetTargetFPS(60);
            else
                SetTargetFPS(0);
        }

        BeginDrawing();
            ClearBackground(RAYWHITE);

            BeginMode3D(camera);
                DrawGrid(100, 1.0f);
            EndMode3D();

            DrawText("Press F to Lock/Unlock FPS", 0, 20, 20, MAROON);
            DrawFPS(0, 0);
        EndDrawing();
    }

    CloseWindow();
    return 0;
}

[raysan5]

@hanaxars I'm afraid this change couples camera.h module to raylib, the intention of the module was avoiding that if possible

[hanaxars]

rcamera.h was already coupled to raylib with GetMouseDelta() GetMouseWheelMove() IsKeyDown() IsKeyPressed() GetFrameTime() and I thought it was ok to use another GetFrameTime() call.
In this case I can't think a proper way to get frame time without communicating with raylib unfortunately.

[raysan5]

@hanaxars You are right, the coupling was done on last library update and I still need to review it somehow...

Ok, I'm merging it for now...