• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
XavierArias

2D lighting from multiple point sources on GLSL ES 2.0 in iPhone

5 posts in this topic

as i'm a complete noob with shaders i've got some problems while trying to get to work a 2D lighting system that basically covers the screen with a 2D black texture with transparent holes where the lighten areas are.
As i'm using only one texture I guess that i must do this in the fragment shader, right?
Fragment shader:
[source lang="cpp"] #ifdef GL_ES
precision mediump float;
#endif

// Texture, coordinates and size
uniform sampler2D u_texture;
varying vec2 v_texCoord;
uniform vec2 textureSize;

uniform int lightCount;

struct LightSource
{
vec2 position;
float radius;
float strength;
};

uniform LightSource lights[10];

void main()
{
float alpha = 1.0;

vec2 pos = vec2(v_texCoord.x * textureSize.x, v_texCoord.y * textureSize.y);

int i;
for (i = 0; i < lightCount; i++)
{
LightSource source = lights[i];

float distance = distance(source.position, pos);

if (distance < source.radius)
{
alpha -= mix(source.strength, 0.0, distance/source.radius);
}
}

gl_FragColor = vec4(0.0, 0.0, 0.0, alpha);
}
[/source]
The problem is that the performance is really terrible (cannot run at 60fps with 2 lights and nothing else on screen), any suggestions to make it better or even different ways to approach this problem?
By the way, i'm doing this from cocos2d-x, so if anyone has any idea that uses cocos2d elements it will be welcome as well [img]http://public.gamedev.net//public/style_emoticons/default/smile.png[/img]
0

Share this post


Link to post
Share on other sites
Thats not how you want to do it. In the real world at night there is not a black screen over everything. You want to have lights per area or object etc. When drawing an object you should have an idea of what lights are close to it or that will hit it. Then you loop through 1 or 2 lights that actually light the object instead of those 2 plus 8 other lights that dont even affect the object.

Its "lighting" not "lightning".
0

Share this post


Link to post
Share on other sites
Then what is the alternative?
I thought that it would avoid redundant computations to have one texture on top of the other and light every pixel of them.
I've also though that vertex lighting would not be easy to apply as a big texture is represented by a simple quad...

Sorry about the bad spelling, i've corrected every mistake that i've found.
0

Share this post


Link to post
Share on other sites
I don't know about cocos2d-x or IPhone development. So my answer is purely shader oriented.
Because the shader does not seem complicated, and only evaluated once per pixel, is it really the shader that limits the application? (60fps are quite fast isnt it? Maybe it will drop down anyway later on)


- For the shader: You could try to use the [u]squared[/u] distance, which maybe calculates faster than taking the root for calculating the distance.
The Lightsource can also directly save the squared radius instead of radius.
But be aware that using the squared values for the (adapted) mixfunction will change the lighting into some kind of quadratic attenuation (maybe a benefit ;-))
Still I dont think this will help alot.

- vec2 pos could be calculated within the vertex shader and interpolated as varying to the fragment shader, maybe this is minimal faster (or slower :-))

- Does the speed vary when you use 1 light compared to when you use 10 ? (In order to test if the uniform is valid for the loop condition)

- You could try to make a full screen mesh grid (for example 20x20) instead of one quad and evaluate distances in vertex shader -> interpolate in fragment shader (quality depends on your light source radii)

- If the lights are small you could render multiple smaller quads, one quad per light at the position of the lights (one quad per light) (But this would most probably need an extra pass)


These are just some fast thoughts, not sure if it helps. Still I think, the shader and the task does not seem like a real performance hitter.
0

Share this post


Link to post
Share on other sites
Eeasiest and fastest way is render lights to FBO with one draw call with circle meshes using additive blending. Then draw this texture as fullscreen quad with custom shader that draw black where there are no light using gl20.glBlendFunc(GL_DST_COLOR, GL_SRC_COLOR);

I have made library for this and it can easily give 50lights with cheap andoid phones.
http://code.google.com/p/box2dlights/
0

Share this post


Link to post
Share on other sites
i've tried optimizing this shader with squared distances and so and i haven't got much better results, so i'm going to change all this shader-based lighting for something similar to what kalle_h said, but have to take a look at the additive blending and see if it's what i'm looking for.

Thanks for all your replies.
0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0