• 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
d0Sm4o20

[SOLVED] GLSL subroutine not getting used

1 post in this topic

I'm using a gaussian blur fragment shader. In it, I thought it would be concise to include 2 subroutines: one for selecting the horizontal texture coordinate offsets, and another for the vertical texture coordinate offsets. This way, I just have one gaussian blur shader to manage.

Here is the code for my shader. The {{NAME}} bits are template placeholders that I substitute in at shader compile time:

[CODE]
#version 420

subroutine vec2 sample_coord_type(int i);
subroutine uniform sample_coord_type sample_coord;

in vec2 texcoord;
out vec3 color;

uniform sampler2D tex;
uniform int texture_size;

const float offsets[{{NUM_SAMPLES}}] = float[]({{SAMPLE_OFFSETS}});
const float weights[{{NUM_SAMPLES}}] = float[]({{SAMPLE_WEIGHTS}});


subroutine(sample_coord_type) vec2 vertical_coord(int i) {
return vec2(0.0, offsets[i] / texture_size);
}

subroutine(sample_coord_type) vec2 horizontal_coord(int i) {
//return vec2(offsets[i] / texture_size, 0.0);
return vec2(0.0, 0.0); // just for testing if this subroutine gets used
}

void main(void) {
color = vec3(0.0);

for (int i=0; i<{{NUM_SAMPLES}}; i++) {
color += texture(tex, texcoord + sample_coord(i)).rgb * weights[i];
color += texture(tex, texcoord - sample_coord(i)).rgb * weights[i];
}
}
[/CODE]

Here is my code for selecting the subroutine:

[CODE]
blur_program->start();
blur_program->set_subroutine("sample_coord", "vertical_coord", GL_FRAGMENT_SHADER);
blur_program->set_int("texture_size", width);
blur_program->set_texture("tex", *deferred_output);
blur_program->draw(); // draws a quad for the fragment shader to run on[/CODE]

and:

[CODE]
void ShaderProgram::set_subroutine(constr name, constr routine, GLenum target) {
GLuint routine_index = glGetSubroutineIndex(id, target, routine.c_str());
GLuint uniform_index = glGetSubroutineUniformLocation(id, target, name.c_str());
glUniformSubroutinesuiv(target, 1, &routine_index);

// debugging
int num_subs;
glGetActiveSubroutineUniformiv(id, target, uniform_index, GL_NUM_COMPATIBLE_SUBROUTINES, &num_subs);
std::cout << uniform_index << " " << routine_index << " " << num_subs << "\n";
}[/CODE]


I've checked for errors, and there are none. When I pass in `vertical_coord` as the routine to use, my scene is blurred vertically, as it should be. The `routine_index` variable is also 1 (which is weird, because `vertical_coord` subroutine is the first listed in the shader code...but no matter, maybe the compiler is switching things around)

However, when I pass in `horizontal_coord`, my scene is STILL blurred vertically, even though the value of `routine_index` is 0, suggesting that a different subroutine is being used. Yet the `horizontal_coord` subroutine explicitly does not blur.

What's more is, whichever subroutine comes first in the shader, is the subroutine that the shader uses permanently. Right now, `vertical_coord` comes first, so the shader blurs vertically always. If I put `horizontal_coord` first, the scene is unblurred, as expected, but then I cannot select the `vertical_coord` subroutine! [img]http://public.gamedev.net//public/style_emoticons/default/smile.png[/img]

Also, the value of `num_subs` is 2, suggesting that there are 2 subroutines compatible with my `sample_coord` subroutine uniform.

Just to re-iterate, all of my return values are fine, and there are no glGetError() errors happening.

Any ideas?
0

Share this post


Link to post
Share on other sites
After a lot of pain, I figured out that I was indirectly calling glUseProgram() twice with my framework. The first time, to set the subroutine, the second time, in the draw() method of my shader program object. Apparently subroutine selection *do not* persist in shader program state, so it was being reset on the second call.

Hopefully this saves someone some time! :)
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