• 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
torelocks

"Beginning OpenGL Game Programming 2nd edition" fragment shader compile problems

3 posts in this topic

Hi guys, I'm hoping smeone can give me some advice.
I recently got "Beginning OpenGL Game Programming 2nd edition" by Luke Bernstead.

The first thing i have been doing is doing is reading through and compiling / running the projects.
When I get to the first one with a fragment shader (Chapter 6) however, it bombs out. After some debugging, I've narrowed it down to the fragment shader.

this is the supplied shader:

[code]#version 130

in vec4 color;
out vec4 outColor;

void main(void) {
outColor = color;
}[/code]

I tried changing the shader to something like this, which allows the program to run but everything is rendered black:
[code]void main()
{
gl_FragColor = gl_Color;
}[/code]
[as far as I can tell this is deprecated anyway]


I also mentioned the vert shader works; here it is:
[code]#version 130

uniform mat4 projection_matrix;
uniform mat4 modelview_matrix;

in vec3 a_Vertex;
in vec3 a_Color;
out vec4 color;

void main(void)
{
vec4 pos = modelview_matrix * vec4(a_Vertex, 1.0);
gl_Position = projection_matrix * pos;
color = vec4(a_Color, 1.0);
}
[/code]

When I investigate what glGetShaderInfoLog says, all i get is:
[quote]- Fragment Shader Fai[/quote]
useful, huh?


Unfortunately, I'm new to this whole thing and after a lot of searching on-line I'm still at an impasse. I hoping by posting here someone would be able to help me.

Oh yeah, my laptop's graphics card is: ATI Radeon HD 4500 series. I ran GPUCapsViewer; which told me that the card is fully shader version 1.3 compatible.

Any help appreciated, am i doing something wrong?!
0

Share this post


Link to post
Share on other sites
[quote name='torelocks' timestamp='1316466719' post='4863520']
Hi guys, I'm hoping smeone can give me some advice.
I recently got "Beginning OpenGL Game Programming 2nd edition" by Luke Bernstead.

The first thing i have been doing is doing is reading through and compiling / running the projects.
When I get to the first one with a fragment shader (Chapter 6) however, it bombs out. After some debugging, I've narrowed it down to the fragment shader.

this is the supplied shader:

[code]#version 130

in vec4 color;
out vec4 outColor;

void main(void) {
outColor = color;
}[/code]

I tried changing the shader to something like this, which allows the program to run but everything is rendered black:
[code]void main()
{
gl_FragColor = gl_Color;
}[/code]
[as far as I can tell this is deprecated anyway]


I also mentioned the vert shader works; here it is:
[code]#version 130

uniform mat4 projection_matrix;
uniform mat4 modelview_matrix;

in vec3 a_Vertex;
in vec3 a_Color;
out vec4 color;

void main(void)
{
vec4 pos = modelview_matrix * vec4(a_Vertex, 1.0);
gl_Position = projection_matrix * pos;
color = vec4(a_Color, 1.0);
}
[/code]

When I investigate what glGetShaderInfoLog says, all i get is:
[quote]- Fragment Shader Fai[/quote]
useful, huh?


Unfortunately, I'm new to this whole thing and after a lot of searching on-line I'm still at an impasse. I hoping by posting here someone would be able to help me.

Oh yeah, my laptop's graphics card is: ATI Radeon HD 4500 series. I ran GPUCapsViewer; which told me that the card is fully shader version 1.3 compatible.

Any help appreciated, am i doing something wrong?!
[/quote]
If you are going to change the fragment shader, it needs to be compatible with the vertex shader. You have a varying variable called [i]color[/i] from the vertex shader being passed to the fragment shader but where is it declared? You need to do this if you want to use the built-in type:
[code]#version 130

in vec4 color;

void main(void) {
gl_FragColor = color;
}[/code]
Personally, when I am learning from a book with source code, I don't build the projects until I understand the underlying code. That way whether it compiles or not, I will be in a position to get it to work. The alternative is too frustrating.
0

Share this post


Link to post
Share on other sites
Hi torelocks,

Sorry you are having trouble with the source code that came with the book. Could you try the latest bug fix release from here: http://www.kazade.co.uk/downloads/boglgp/

Let me know if you still have trouble,

Thanks,

Luke.
0

Share this post


Link to post
Share on other sites
Hi guys,
firstly thanks for your quick replies.

@jesse, you make a very good point about understanding the content before compiling. This is what I'm trying to do, chapter by chapter but i was totally stumped with this one.
Thanks for pointing out that the output vertex variables need to be named the same as the input fragment ones...that was a detail I missed!

@Luke, much thanks for those bugfixes; the problem i was hitting is fixed. it was indeed one of the problems referred to in the fix notes:
[quote] * Since release, certain drivers (specifically AMD) started requiring precision qualifiers in the fragment shader causing the examples to fail while compiling the shader. All shaders are now fixed and an accompanying document gives a brief explanation of the issue.[/quote]

I did notice that one of the other bug-fixes is not fixed (as far as I can tell):
[quote] An incorrect size was passed to glGetShaderInfoLog causing any log output to be truncated. [/quote]


I'm guessing this is Luke Benstead...if so, thanks for writing a clear and readable book. One suggestion I would make is to place links to these bug-fixes on:
[url="http://glbook.gamedev.net"]http://glbook.gamedev.net[/url]
as the book says that's the support web-site and there's currently no support available there.


Again, thanks for your help. It's great to see a friendly and helpful community. Hopefully i can give some back down the line :)

T
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