How does the default GLSL shaders look like? for version 330

Question

What do the default vertex, fragment and geometry GLSL shaders look like for version #330?

I'll be using #version 330 GLSL Version 3.30 NVIDIA via Cg compiler, because that is what my graphics card supports.

With default shaders, I mean shaders that do the same exact thing as the graphics card would do when the shader program is turned off.

I can't find a good example for #version 330. Been googling all day. Not sure if the term default shader is called something else like trivial or basic and if that is why I can't find it.

Any recommendations for a book with version 330 or link to an easy beginner tutorial with version 330 would be great as well.

example of a trivial vertex shader in #version 110, does the default vertex transformation

#version 110

void main()
{
    gl_Position = gl_ProjectionMatrix * gl_ModelViewMatrix * gl_Vertex;
}

example of a trivial fragment shader in #version 110, turns color into red

#version 110

void main()
{
    gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
}

In the most technical sense, you cannot turn off the shader in core GL 3.3, since the ability to render without shaders was removed in core OpenGL contexts. The OpenGL Wiki maintains a list of shader-based tutorials (one of which is mine), but none of them have shaders which directly map to what fixed-functionality would do. That's probably the worst way to learn shader-based programming anyway. — Nicol Bolas

Robert Rouhani Robert Rouhani · Accepted Answer · 2011-12-30T01:47:42

There are no "default" shaders with OpenGL. It looks like what you want a very simple example of a shader that transforms vertices to clip space and gives them a color, so here you go:

Vertex shader:

#version 330

layout(location = 0)in vec4 vert;

uniform mat4 projection;
uniform mat4 view;
uniform mat4 model;

void main()
{
    gl_Position = projection * view * model * vert;
}

Fragment shader:

#version 330

out vec4 fragColor;

void main()
{
    fragColor = vec4(1.0, 0.0, 0.0, 1.0);
}

The core OpenGL 3.3 profile drops support for a lot of old fixed-function things like the matrix stack. You are expected to handle your own matrices and send them to your shaders. There is no ftransform, and gl_Position is pretty much the only valid gl_* variable.

While glBindAttribLocation is not deprecated, the preferred method of defining the location of vertex attributes is through "layout(location = x)" in GLSL.

In the vertex shader, "attribute" is now "in" and "varying" is now "out". In the fragment shader, "varying" is now "in" and "gl_FragColor" is defined by an "out" variable. I believe that gl_FragColor is still valid, but now it's possible to use an out variable to define the color.

This tutorial is very good and teaches core OpenGL and GLSL 3.30, I would recommend you use it to help you learn more about GLSL. Also remember that the GLSL Reference Pages is your friend.

How does the default GLSL shaders look like? for version 330

1 Answers