OpenGL_Functions.md

OpenGl Functions

glGetString

return a string describing the current GL connection

glGenBuffers

generate buffer object names

glBindBuffer

bind (select -> for use) a named buffer object to a specified target

buffer == 0 -> any previously bound buffer object gets unbound -> frees memory

buffer are local to the shared object space of the current GL rendering context

glBufferData

creates and initializes / overwrites a buffer object's data store

data == NULL -> no data gets copied

buffer object currently bound to target is used

glEnableVertexAttribArray

enable a generic vertex attribute array

glVertexAttribPointer

define an array of generic vertex attribute data

glCreateShader

creates a shader object

glShaderSource

replaces the source code in a shader object

glCompileShader

compiles a shader object

glGetShaderiv

returns a parameter from a shader object

glGetShaderInfoLog

returns the information log for a shader object

in length the length of the output string (excluding NULL termination character) gets returned, unless length is set to NULL

glDeleteShader

deletes a shader object

undoes glCreateShader

shader objects that are attached to a program doesn't get immediately deleted -> gets flagged for deletion when detached

glCreateProgram

creates a program object

program objects are used to link (multiple) shader together

glAttachShader

attaches a shader object to a program object -> this shader will be included in the link operations that will be performed on the specified program

glLinkProgram

links a program object

when the program is currently in use:

• linking successful -> new executables will get installed
• linking not successful -> old executables will stay and the programs link status will be set to GL_FALSE

##glValidateProgram validates a program object

typically useful only during development

glUseProgram

installs a program object as part of current rendering state

glClear

clear buffers to preset values

glDrawArrays

render primitives from array data

glDeleteProgram

deletes a program object

undoes glCreateProgram

when the program is currently in use -> flagged for deletion -> gets deleted when not in use any more

glDrawElements

render primitives from array data

glDebugMessageCallback

specify a callback to receive debugging messages from the GL

glEnable

enable server-side GL capabilities

glGetError

return error information

should be called repeatedly -> until returns GL_NO_ERROR

glGetUniformLocation

returns the location of a uniform variable

querying a specified uniform variable in a specified program

has to be called for each element <- when querying an array

has to be used after linking

glUniform4f

specify the value of a uniform variable for the current program object

operates on the currently used program

glGenVertexArrays

generate vertex array object names

glBindVertexArray

bind a vertex array object

glGenTextures

generate texture names

glBindTexture

bind a named texture to a texturing target

glTexParameteri

set texture parameters

glTexImage2D

specify a two-dimensional texture image

texturing allows elements of an image array to be read by shaders

glActiveTexture

select active texture unit

glBlendFunc

specify pixel arithmetic (the factors for source and destination blending)

glBlendEquation

specify the equation used for both the RGB blend equation and the Alpha blend equation

glMapBuffer

map all of a buffer object's data store into the client's address space

glUnmapBuffer

release the mapping of a buffer object's data store into the client's address space

glBufferSubData

updates a subset of a buffer object's data store