• 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
KaiserJohan

Light attenuation not working correctly

5 posts in this topic

Hello,

 

I have the vertex shader like this:

 

const std::string gVertexShader =	"#version 330								                            \n	\
                                                                                                                \n  \
                                        layout(std140) uniform DefaultUniform                                   \n  \
                                        {                                                                       \n  \
                                            vec4 Color;                                                         \n  \
                                            mat4 WVPMatrix;                                                     \n  \
                                            mat4 WorldMatrix;                                                   \n  \
                                                                                                                \n  \
                                            vec4  AmbientLight;                                                 \n  \
                                            vec4  LightIntensity;                                               \n  \
                                            vec3  LightPosition;                                                \n  \
                                            float LightAttenuation;                                             \n  \
                                        };                                                                      \n  \
                                                                                                                \n	\
                                        layout(location = 0) in vec3 vert_position;				                \n	\
                                        layout(location = 1) in vec3 vert_normal;					            \n	\
                                                                                                                \n	\
                                        out vec4 frag_color;                                                    \n	\
                                        out vec4 frag_position;                                                 \n	\
                                        out vec4 frag_normal;                                                   \n	\
                                                                                                                \n	\
                                        out vec4  frag_ambientLight;                                            \n	\
                                        out vec4  frag_lightIntensity;                                          \n	\
                                        out vec4  frag_lightPosition;                                           \n	\
                                        out float frag_lightAttenuation;                                        \n	\
                                                                                                                \n	\
                                        void main()									                            \n	\
                                        {											                            \n	\
                                            gl_Position = WVPMatrix * vec4(vert_position, 1.0);                 \n  \
                                                                                                                \n  \
                                            frag_color    = Color;                                              \n  \
                                            frag_position = WorldMatrix * vec4(vert_position, 1.0);             \n  \
                                            frag_normal   = normalize(WorldMatrix * vec4(vert_normal, 1.0));    \n  \
                                                                                                                \n  \
                                            frag_ambientLight     = AmbientLight;                               \n  \
                                            frag_lightIntensity   = LightIntensity;                             \n  \
                                            frag_lightPosition    = vec4(LightPosition, 1.0);                   \n  \
                                            frag_lightAttenuation = LightAttenuation;                           \n  \
                                        }											                            \n";

 

 

I have a fragment shader defined like this:

 

const std::string gFragmentShader =	"#version 330									                                            \n \
                                                                                                                                    \n \
                                        in vec4 frag_color;                                                                         \n \
                                        in vec4 frag_position;                                                                      \n \
                                        in vec4 frag_normal;                                                                        \n \
                                                                                                                                    \n \
                                        in vec4  frag_ambientLight;                                                                 \n \
                                        in vec4  frag_lightIntensity;                                                               \n \
                                        in vec4  frag_lightPosition;                                                                \n \
                                        in float frag_lightAttenuation;                                                             \n \
                                                                                                                                    \n \
                                        out vec4 finalColor;						                                                \n \
                                                                                                                                    \n \
                                        vec4 CalcLightIntensity()                                                                   \n \
                                        {                                                                                           \n \
                                            vec4 positionDiff = frag_lightPosition - frag_position;                                 \n \
                                                                                                                                    \n \
                                            return frag_lightIntensity * (1 / (1.0 + frag_lightAttenuation * abs(positionDiff)));   \n \
                                        }                                                                                           \n \
                                                                                                                                    \n \
                                                                                                                                    \n \
                                        void main()										                                            \n \
                                        {												                                            \n \
                                            vec4 attenIntensity = CalcLightIntensity();                                             \n \
                                                                                                                                    \n \
                                            vec4 lightDir      = normalize(frag_position - frag_lightPosition);                     \n \
                                            float angIncidence = dot(frag_normal, lightDir);                                        \n \
                                            angIncidence       = clamp(angIncidence, 0, 1);                                         \n \
                                                                                                                                    \n \
                                            finalColor = (frag_color * attenIntensity * angIncidence) +                             \n \
                                                         (frag_color * frag_ambientLight);                                          \n \
                                        }												                                            \n";

 

I have a single positional light, and I want to apply light attenuation so the intensity fades over distance. But, for some reason, the attenuation does not work at all - the light does not decrease on distance. Can someone spot what the problem is? I'm pulling my hair out trying to debug it

Edited by KaiserJohan
0

Share this post


Link to post
Share on other sites

I think you should be using the 'length' function in CalcLightIntensity instead of the 'abs' function.

0

Share this post


Link to post
Share on other sites

I tried it; same result.

 

For example, when I move the light in Z direction, everything at the current Z position and 'down' (-Z) gets fully lit while everything directly 'behind' (+Z) is not lit at all. 

 

In case it matters the 'LightIntensity' is Vec4(1.0f), 'LightAttenuation' is 1.0f

0

Share this post


Link to post
Share on other sites

In your vertex shader, you are computing the vertex normal with

  frag_normal = normalize(WorldMatrix * vec4(vert_normal, 1.0)); 

In homogenous coordinates, the last "w" scalar value set to 1.0 means that vert_normal is a point. As it is a mere unpositioned vector, i think using 0.0 should fix your bug.

 

 

Moreover, normalizing the interpolation variable frag_normal (set as "smooth out" and "smooth in" by default) will lead to incorrect normal vectors as they won't stay normed during their interpolation across vertices. You should normalize it in the fragment shader.

Edited by PixelSmasher
1

Share this post


Link to post
Share on other sites

Yes I fixed it finally; I added the suggestions you made, in addition I also found out that 'LightAttenuation' variable was not uploaded correctly to the shader - it was set to 0.0, which wouldve removed any attenuation at all

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