odin-gl: opengl loader in Odin

Includes procedures to load OpenGL function pointers. Currently only supports the core profile, up to version 4.6. Based on the output from the glad webservice using 4.6 core.

Note: You will be required to pass your own GetProcAddress equivalent (wglGetProcAddress, glXGetProcAddress, glfwGetProcAddress, etc.), for example:

gl.load_up_to(4, 5, proc(p: rawptr, name: cstring) do (cast(^rawptr)p)^ = glfw.GetProcAddress(name); );

odin-glfw also provides a useful helper you can pass straight to gl.load_up_to:

gl.load_up_to(4, 5, glfw.set_proc_address);

NOTE: It is recommended to put this into the shared collection:

cd /path/to/Odin/shared
git clone https://github.com/vassvik/odin-gl.git

Extra utility procedures (Outdated. See the end of gl.odin)

Some useful helper procedures can be found in helpers.odin, for tasks such as:

• loading vertex, fragment and compute shaders (from source or files) using load_shaders_file, load_shaders_source, load_compute_file and load_compute_source
• grabbing uniform and attribute locations using get_uniform_location and get_attribute_location
• getting all active uniforms from a program using get_uniforms_from_program
• hot reloading of shaders (windows only right now) using update_shader_if_changed and update_shader_if_changed_compute

Debug mode

Each gl call will be appended by a debug helper calling glGetError() if compiled with -debug. This can be useful to detect incorrect usage. Sample output (also outputting the NO_ERRORS case for the sake of showcasing):

glGetError() returned NO_ERROR
   call: glTexImage2D(GL_TEXTURE_2D=3553, 0, 34836, 1150, 1024, 0, GL_RGBA=6408, GL_FLOAT=5126, 0x0)
   in:   C:/<snip>/texture.odin(156:23)
glGetError() returned NO_ERROR
   call: glEnable(GL_DEBUG_OUTPUT=37600)
   in:   C:/<snip>/main.odin(185:6)
glGetError() returned NO_ERROR
   call: glGetError() -> 0 
   in:   C:/<snip>/main.odin(193:5)
glGetError() returned INVALID_ENUM
   call: glEnable(INVALID_ENUM=123123123)
   in:   C:/<snip>/main.odin(194:5)
glGetError() returned INVALID_VALUE
   call: glPointSize(-1.000)
   in:   C:/<snip>/main.odin(195:5)
glGetError() returned NO_ERROR
   call: glDisable(GL_SCISSOR_TEST=3089)
   in:   C:/<snip>/main.odin(270:6)
glGetError() returned NO_ERROR
   call: glViewport(0, 0, 1150, 1024)
   in:   C:/<snip>/main.odin(271:6)
glGetError() returned NO_ERROR
   call: glClearColor(0.800, 0.800, 0.800, 1.000)
   in:   C:/<snip>/main.odin(272:6)