This module shows... a) how GLSL error locations are presented depending on how the shader source is passed (one string vs array of strings), b) whether a single token can spread across several source strings.

shaderlines.py

'''
This module shows...
a) how GLSL error locations are presented depending on how the shader source is passed
   (one string vs array of strings),
b) whether a single token can spread across several source strings.

'''

import ctypes
from OpenGL import GL

# This is a deep dependency from my framework,
# please replace it with your own decorator that makes a function run through a valid GL context
from debugwindow import gltest


# An example shader with an error in line 5

source = '''\
#version 330                          // 1
                                      // 2
void main() {                         // 3
                                      // 4
    gl_Position = vec4(1,2,three,4);  // 5   error here
                                      // 6
}                                     // 7
'''

# This shader is correct, but is split into two strings inside a token

alt_source_list = [
    '#version 330\nvo',
    'id main() { gl_Position = vec4(0); }'
]


@gltest
def run(splits):

    shader = GL.glCreateShader(GL.GL_VERTEX_SHADER)

    if splits:
        keep_eols = True
        source_lines = source.splitlines(keep_eols)     #  It is important to keep newlines.
        c_sources = map(ctypes.c_char_p, source_lines)
    else:
        c_sources = [ctypes.c_char_p(source)]

    
    ctype_char_p_arr = ctypes.c_char_p * len(c_sources)
    c_sources_array = ctype_char_p_arr(*c_sources)

    if splits:
        assert len(c_sources) > 1
    else:
        assert len(c_sources) == 1

    GL.glShaderSource.wrappedOperation(shader, len(c_sources), c_sources_array, None)
    GL.glCompileShader(shader)
    print 'Compile status:', bool(GL.glGetShaderiv(shader, GL.GL_COMPILE_STATUS))
    print 'Info log:'
    print GL.glGetShaderInfoLog(shader)


@gltest
def run2():

    shader = GL.glCreateShader(GL.GL_VERTEX_SHADER)
    c_sources = map(ctypes.c_char_p, alt_source_list)
    ctype_char_p_arr = ctypes.c_char_p * len(c_sources)
    c_sources_array = ctype_char_p_arr(*c_sources)

    assert len(c_sources) == 2

    GL.glShaderSource.wrappedOperation(shader, len(c_sources), c_sources_array, None)
    GL.glCompileShader(shader)
    print 'Compile status:', bool(GL.glGetShaderiv(shader, GL.GL_COMPILE_STATUS))
    print 'Info log:'
    print GL.glGetShaderInfoLog(shader)



def main():
    print '# Shader as lines:'
    print '(Expected an error in line 5)'
    run(True)
    print '# Shader as one block:'
    print '(Expected an error in line 5)'
    run(False)
    print '# Tokens across block'
    print '(Expected success if the token can span through strings)'
    run2()


if __name__ == '__main__':
    main()