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Thread: Question about keybindings

  1. #1
    Join Date
    May 2013

    Question Question about keybindings


    I'm using the basic2d example as the base for my code as it's the simplest one.
    The code is a mess for I'm in the phase of "trying to access the clanlibs functionality".

    So in the following code I'm trying to capture the key-presses of ASDW and process them as movement. The code compiles and actually works, however it is "jerky". The movement isn't stable, it slows down and then regains speed. As the functionality is very basic, I must be doing something wrong.

    It could be my system? But I don't know...
    Specs: CL2.3, Ubuntu 12.04

    #include "precomp.h"
    #include "keytest.h"
    // The start of the Application
    int keytest::start(const std::vector<CL_String> &args)
    	quit = false;
    	// Set the window
    	CL_DisplayWindowDescription desc;
    	desc.set_size(CL_Size(800, 600), true);
    	CL_DisplayWindow window(desc);
    	// Connect the Window close event
    	CL_Slot slot_quit = window.sig_window_close().connect(this, &keytest::on_window_close);
    	// Connect a keyboard handler to on_key_up()
    	CL_Slot slot_input_up = (window.get_ic().get_keyboard()).sig_key_up().connect(this, &keytest::on_input_up);
    	// Get the graphic context
    	CL_GraphicContext gc = window.get_gc();
    	CL_Font font(gc, "tahoma", 20);
    	CL_ResourceManager resources("Resources/resources.xml");
     	CL_Sprite sprite1(gc, "teapot", &resources);
     	CL_Sprite sprite2(gc, "ixwin", &resources);
     	CL_Sprite sprite3(gc, "teapot", &resources);
    	// Load images into set coordinates
     	CL_Sprite grid_A1(gc, "tile_water", &resources);
     	CL_Sprite grid_A2(gc, "tile_water", &resources);
     	CL_Sprite grid_A3(gc, "tile_water", &resources);
     	CL_Sprite grid_B1(gc, "tile_water", &resources);
     	CL_Sprite grid_B2(gc, "tile_grass", &resources);
     	CL_Sprite grid_B3(gc, "tile_water", &resources);
     	CL_Sprite grid_C1(gc, "tile_water", &resources);
     	CL_Sprite grid_C2(gc, "tile_water", &resources);
     	CL_Sprite grid_C3(gc, "tile_water", &resources);
    	unsigned int last_time = CL_System::get_time();
    	float playerX = -10.0f;
    	float playerY = 0.0f;
    	CL_InputDevice &keyboard = window.get_ic().get_keyboard();
    	// Run until someone presses escape
    	while (!quit)
    		unsigned int current_time = CL_System::get_time();
    		float time_delta_ms = static_cast<float> (current_time - last_time);
    		last_time = current_time;
    		// background
    		// Draw the bg-images (3x3 grid)
    		grid_A1.draw(gc,(float) playerX+0,			(float) playerY+0);
    		grid_A2.draw(gc,(float) playerX+20.0f,		(float) playerY+0);
    		grid_A3.draw(gc,(float) playerX+40.0f,		(float) playerY+0);
    		grid_B1.draw(gc,(float) playerX+0,			(float) playerY+20.0f);
    		grid_B2.draw(gc,(float) playerX+20.0f,		(float) playerY+20.0f);
    		grid_B3.draw(gc,(float) playerX+40.0f,		(float) playerY+20.0f);
    		grid_C1.draw(gc,(float) playerX+0,			(float) playerY+40.0f);
    		grid_C2.draw(gc,(float) playerX+20.0f,		(float) playerY+40.0f);
    		grid_C3.draw(gc,(float) playerX+40.0f,		(float) playerY+40.0f);
    		sprite1.draw(gc, 400, 300);
    		// Here is the keyboard presses
    		if( keyboard.get_keycode(CL_KEY_A))
    			playerX -= 2.0f;
    		if( keyboard.get_keycode(CL_KEY_D)) 
    			playerX += 2.0f;
    		if( keyboard.get_keycode(CL_KEY_W))
    			playerY -= 2.0f;
    		if( keyboard.get_keycode(CL_KEY_S))
    			playerY += 2.0f;
    		// Flip the display, showing on the screen what we have drawed
    		// since last call to flip()
    		// This call processes user input and other events
    	return 0;
    // A key was pressed
    void keytest::on_input_up(const CL_InputEvent &key, const CL_InputState &state)
    	if( == CL_KEY_ESCAPE)
    		quit = true;
    // The window was closed
    void keytest::on_window_close()
    	quit = true;

  2. #2
    ClanLib Developer
    Join Date
    May 2007


    Try changing:
    "playerX -= 2.0f;"
    "playerX -= time_delta_ms * 0.2f" <--- You may need to change this value

    Also remove the CL_System::sleep(10), since you have a window.flip(1), it's not required.

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