Simple DirectMedia Layer (SDL) is a cross-platform multimedia library designed to provide low level access to audio, keyboard, mouse, joystick, 3D hardware via OpenGL, and 2D video framebuffer.

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161 views

Why am I getting these artifacts when rendering polygons with OpenGL and SDL from far distance?

I'm working in a toy BSP (quake3 version) renderer. I started creating the context and handling the input with GLFW but then I switched over SDL. The performance change was amazing with SDL leading ...
3
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3answers
813 views

Translating an object in the rotation direction

I am creating a graphical scene with OpenGL and SDL, and I'm running into a problem in regards to translating an object in its rotation direction. Each of the graphical objects in the scene has a ...
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4answers
8k views

Trap mouse in SDL

How can I trap the user's mouse inside my game? It's not a fullscreen game, but I want it so that the user cannot drag the mouse to outside the screen. Do I have to check the coordinates of the mouse ...
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1answer
159 views

Entity to tile collision detection (C++, SDL)

I'm currently trying to handle collisions between entities and a tilemap, but I've hit a problem. My tiles are stored simply as integer tile IDs in a multidimensional array, and I wanted to perform a ...
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1answer
133 views

Handling input in ECS for multiple characters

I've been reading into Entity-Component-Systems, and they seem rather handy. However, I don't quite understand how input should be handled and after googling and looking thru GDSE posts, I've become ...
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1answer
277 views

Zooming In SDL 2.0

I'm currently working on a project in which I render pictures raw. That is I use simple IMG_LoadTexture(), SDL_RenderCopy(). I want the program to be able to zoom in/out and textures to be scaled to ...
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1answer
44 views

SDL.NET no longer detecting modifier keys

I'm using SDL.NET with C#. Recently, a bug has appeared where the library does not detect if the shift key is held down; although it used to do so. private static void KeyboardEventHandler(object ...
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1answer
313 views

SDL & OpenGL - Artifacts when multisampling

Im trying to render a model with anialiasing using OpenGL and SDL, but when I do I get strange artifacts. When I render with antialiasing disabled everything looks fine. When antialiasing is ...
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2answers
77 views

Kerning between glyphs using SDL2_ttf

I'm loading a number of characters (using SDL2_ttf) into a texture atlas to improve performance. The glyphs can be separately rendered correctly, however, how can you find the kerning distance ...
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0answers
34 views

Strange offset when accessing pixels from an SDL surface

I am using a routine to map a triangle from one surface to another. The problem is that the function below chooses the correct pixel to draw on the destination surface, but the pixel selected from the ...
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3answers
238 views

2D Rendering Based On Y Coordinates

I'm trying to build an RPG worldbuilder. I have seperate classes for images. Like this. Object1::Object1(int x, int y, CSDL_Setup *sdl_set, int *p_CamX, int *p_CamY) { X_pos = x; Y_pos = y; ...
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0answers
133 views

Creating A Selectable Object in SDL/C++

I'm trying to create a clickable object. I wrote a pseudo code to try it. When I add a new member to object it works fine, that is when I hold the mouse cursor on the rectangle determined it returns ...
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2answers
158 views

Getting if a key was released/pressed this frame (C++/SDL2)

Getting if a key is currently down is easy. Just return keys[scancode]: switch (ev.type) { case SDL_KEYDOWN: keys[ev.key.keysym.scancode] = true; break; case SDL_KEYUP: ...
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2answers
188 views

Segmentation fault adding SDL_Surface

I'm trying to add a new SDL_Surface to my whack-a-mole clone code but even if I set it to null it wont let me. game.h #include<SDL2/SDL.h> #include<SDL2/SDL_image.h> #include<string&...
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1answer
327 views

How to use traditional pixel coordinates system in OpenGL? (with C++/SDL2)

I find the normalized, centralized coordinate system used in OpenGL weird and annoying, is there anything I can do at all to make it work like normal pixel coordinates on everything ever except OpenGL?...
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1answer
181 views

Pathfinding with differently-sized objects on tile map [duplicate]

It's my first RTS game and I'm having trouble finding out how to make infantry take less space than tanks. Right now I have 1 tank and 1 infantry type ready with sprites, pathfinding, selection and ...
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1answer
2k views

Porting SDL OpenGL Game to Android and IOS

I am currently learning OpenGL (3.0+) with C++. I am using SDL for input handling, window creation, etc., GLEW to use OpenGL and call OpenGL Functions, and GLM for OpenGL Math stuff. If I fully ...
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1answer
39 views

Bouncing projectile off of sprite, the sides work but top and bottom do not

I'm having a problem bouncing a projectile off a sprite, we've been asked to move the projectile using the equations of motions which makes things a little more difficult but as far as I can see what ...
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1answer
166 views

Fastest way to render image data from buffer

Currently I am doing my rendering by using a 3D array window_width x window_height x rgb as a buffer, then looping through the buffer and plotting pixels on screen using SDL2 (SDL_RenderDrawPoint). I ...
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1answer
365 views

Where can I get correct pitch parameter for SDL_RenderReadPixels function in SDL2?

I have a texture created with SDL_TEXTUREACCESS_TARGET access and I want to get all it's pixels with SDL_RenderReadPixels() function. One of the function parameters is pitch and I don't really know ...
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1answer
138 views

Keyboard input vs character movement encapsulation

In our game created with c++ and sdl we are having difficulty delegating how the main character should be controlled. We have a keyboard class and a sprite class for the main character, but are ...
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3answers
662 views

Problem getting mouse events while keys held down in SDL2

I'm attempting to write input capturing code using SDL2 on Windows. However, I'm running into a problem. Whenever a key is held down, the SDL event queue has no mouse movement, nor will the mouse ...
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2answers
182 views

SDL draw dynamic select box

this might seem obvious to many, but I'm stuck and I cannot find any tutorial which helped me, so it would be great to find the answer here. I tried to make a rectangle like you have in RTS games, so ...
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1answer
248 views

Should I cull off-screen objects in SDL2

My game will have a large number of objects moving offscreen at any given time, can i just render them all with SDL_RenderCopy even though they are off screen or should I only render them if they are ...
7
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3answers
1k views

What is the contents of the buffer *after* a call to glSwapBuffers()?

(SDL_GL_SwapBuffers() in particular) When you have drawn a scene, and you call swap-buffers, it is routine to then glClear() the scene before drawing anything; if you don't clear, what is the ...
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3answers
6k views

Smooth Sprite Movement - Don't Add Velocity to Position?

I am trying to figure out if there is a way to move a sprite smoothly on the screen at different speeds without stuttering, but keeping the effect that it's moving smoothly; especially at faster ...
3
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1answer
954 views

Rendering text with SDL2 and OpenGL

I've been trying to have text rendering in my OpenGL scene using SDL2. The tutorial I came across is this one Rendering text I followed the same code, and I get text rendering fine. However the issue ...
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2answers
169 views

Colour values of a pixel array from a spritesheet image wrong (C++, SDL2)

So basically what i want to do is create a 2D tile based rendering system in C++ that renders each pixel on the screen manually. Rendering an individual pixel on the screen works just fine (or render ...
0
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1answer
169 views

Is this a good way to regulate fps?

In all of my tests I always regulate the fps by using this method. const int fps = 30; const int msPerFrame = 1000/fps; // 33 ms per frame, so it's more like 30.3030 fps while(true) { const int ...
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1answer
56 views

Box platform collision

I'm working on a platform game and my collision code is to picky. I can't exactly do aabb(?) because the map is represented as metatiles. (23-24 16x16 tiles make up a 300ish pixel resolution.) My game ...
0
votes
1answer
232 views

SDL pixel access very slow

I'm using SDL and need to plot pixels one by one on the screen. When I do this, it's extremely slow. I followed the tutorial here: http://www.programmersranch.com/2014/02/sdl2-pixel-drawing.html ...
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2answers
265 views

Are SDL games trivially portable from Linux to Windows?

I have a small game made with SDL2 and I want to port it to Windows. Would I hav eto write a lot of #ifdefs to port it or will the very same code work on Windows and Linux? Or is it more complicated? ...
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0answers
120 views

Pixel buffers in SDL

I'm using SDL and c++ and trying to create a class to work on pixel basics. The buffer is a multidimensional char array. char buff[scW][scH]; The video mode is being set by a SDL_SetVideoMode(scW,...
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1answer
554 views

How do I implement a fixed delta time step with a SDL_Delay(15ms) precision

So I am using SDL2.0 for making a Game Engine. Where I am having a problem is using SDL_Delay(). SDL_Delay's minimum delay time is 15ms, I've tried everything, and my FPS is Stuck at 64 because of ...
4
votes
1answer
768 views

How can I optimize per-pixel drawing in SDL?

I've been messing around with C++ the last few days and I'm trying to figure out how to draw the screen pixel by pixel each frame. It sounded simple enough at first, but then I realized for loops ...
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0answers
35 views

Pseudo 3D questions in SDL/C++ [duplicate]

I'm going for a SNES mode 7 effect. From my understanding you do maths, to grab the current pixel from z values. Resulting from this math you take an image and then transcribe it into the screen for a ...
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1answer
123 views

How do I compile further libraries into my game? [closed]

This might be vague; I don't know how to search for this. How do I link a GUI framework (in my case, CEGUI) to a graphics framework (in my case, SDL)? I'm using a Mac. My mental model on how to add ...
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1answer
320 views

Problem with 2D matrix transform og shapes

I have set myself onto the task of creating a class BaseObject, which represents a graphics object with an associated shape as the member variable shape, which is a pointer an object Polygon. I'll ...
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1answer
70 views

How do I destroy a SDL_Finger pointer?

Hello I'm using SDL with C++ and I got this code: void handleEvents() { SDL_Finger* finger = SDL_GetTouchFinger(SDL_GetTouchDevice(0), 0); } I do not know what SDL does inside the GetTouch ...
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votes
1answer
241 views

How to handle pathfinding and path following with sprites the same size as the grid?

The game I am working on is currently using 32X32 collision boxes. I have implemented a working AI (A* - path finding method) which is based on the Grid Size. Lets say that I use that 16x16 grid , ...
0
votes
2answers
32 views

Question about where to put a method [closed]

I'm working on a tower defense game as a class project and i got it to a kinda working level(creep spawns, towers can shoot etc), but i have a problem with my classes. Currently the towers shoot but ...
0
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1answer
217 views

How to make a stereoscopic 3D Game with SDL for iOS

I was looking up google for an answer the whole night but didn't find anything. Yesterday I found some VR demos and games on the AppStore, with stereoscopig (dual rendered) screens. So you put your ...
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1answer
282 views

SDL_PollEvent very slow on SDL2, but works fine on SDL1.2

I have this simple app that displays a screen and handles the quit event: while( SDL_PollEvent( &e ) != 0 ) { //User requests quit if( e.type == SDL_QUIT ) { ...
3
votes
1answer
249 views

SDL2 jagged/staircase edges

I am using SDL2 and SDL2 Image to render png images. When I rotate the textures, they turn out very ugly, like this: This is the code responsible for the rotation and alpha mod. SDL_Rect srcRect; ...
0
votes
1answer
203 views

Calculate slope for linear interpolated movement

I want to move rectangles to their targets the "smooth" way with linear interpolation. I hope this is right. float slope(float x1, float x2, float y1, float y2) { return std::abs((y2 - y1)) / std:...
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1answer
167 views

Problem with SLD/OpenGL

I've started to do sth. with SDL/openGL, but I haven't managed to get this tutorial running yet (http://www.sdltutorials.com/sdl-opengl-tutorial-basics). Since this tutorial, or most tutorials at all,...
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2answers
8k views

How to implement SDL Button/Menu GUI with callbacks?

I have been reading Bjarne Stroustrup's Programming Principles and Practice Using C++ for a while now and am nearing the end of the book. I have to tried to make a very simple game using the SDL ...
1
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1answer
181 views

Reference keyboard keys as “justPressed”, “pressed”, and “justReleased” with SDL in C++

I'm teaching myself 3D graphics with OpenGL and SDL in C++. I'm at a point where I need to be able to query states of individual keys, like so: if (InputManager::justPressed(SDLK_UP)) {} if (...
1
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1answer
928 views

How to pick a 3D object with known mouse coordinates if the camera is rotated 60 degrees?

I am making a simple game engine for a simple RTS game and would like to be able to pick a cube and move it around with the mouse coordinates. The problem is that my camera is rotated 60 degrees just ...
1
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1answer
164 views

SDL2 Gamepad triggers trigger when disconnecting the pad

I'm using MonoGame and SDL2. I'm having a strange problem with the Gamepad. When I disconnect it during the game, before the disconnected event fires, the left and right triggers return values as if ...