OpenGL has a lot of object types: Texture, FBO, VBO, shader, etc. Most of them can be bound, bindings are part of the enormous OpenGL state machine, and it's not obvious which functions use which objects.
This is a (to my knowledge (it's quite limited)) comprehensive list of which bound objects, and other global variables, each function uses. Explicit parameters, such as glCompileShader taking a shader object, are not mentioned.
Rare and deprecated functions and operations, such as glBegin, glGenSamplers and glSecondaryColor, are not mentioned either; I've only included ones I understand and can find practical usecases for.
Finally, this is not a tutorial. It is a complement to one, for people like me who can't wrap our heads around implicit parameters and other global state. I will not explain anything in any detail.
| Bindable object | Create and bind with | Description | Used when drawing? (As input unless otherwise specified) |
|---|---|---|---|
| Shader program | glCreateProgram glUseProgram |
Programmable vertex and fragment rendering instructions | Yes, the bound one |
| Texture | glGenTextures glBindTexture |
N-dimensional array of pixel color data | As input if bound in a texture unit, as output (and input for blending) if pointed to by FBO |
| Texture unit | (automatic) glActiveTexture |
As far as shaders know, you can bind 16 textures at once | Yes, if used by shader |
| Vertex array object (VAO) | glGenVertexArrays glBindVertexArray |
Vertex shader inputs | Yes, the bound one |
| Vertex buffer (VBO) | glGenBuffers glBindBuffer(GL_ARRAY_BUFFER) |
The actual data backing a VAO | If pointed to by bound VAO |
| Element buffer object (EBO) | glGenBuffers glBindBuffer(GL_ELEMENT_ARRAY_BUFFER) |
Vertex indices, for deduplication | If using glDrawElements (uses the one in bound VAO) |
| Framebuffer object (FBO) | glGenFramebuffers glBindFramebuffer |
Which texture to render to | Yes, the bound one |
| Renderbuffer object (RBO) | glGenRenderbuffers glBindRenderbuffer |
A texture, but for non-color data, like depth/stencil | As both input and output, if pointed to by bound FBO, and if enabled by glDepthFunc/glStencilFunc/etc |
| Other global variables (not part of bindable state) |
Set with | Used when drawing? |
|---|---|---|
| The monitor | your hands | As output, if current framebuffer is the default (zero) |
| Viewport | glViewport | If current framebuffer is the default (zero), I think? |
| Scissor | glScissor | Yes |
| Clear color | glClearColor | No (unless you consider glClear drawing) |
| Depth function | glDepthFunc | Yes |
| Stencil function | glStencilFunc | Yes |
| Error flag | glGetError, and every single other function | No |
| Function | Non-argument inputs and outputs |
|---|---|
| glEnable | Various parameters, used only when drawing |
| glDisable | Various parameters, used only when drawing |
| glClear | Clear color (if GL_COLOR_BUFFER_BIT), scissor, things pointed to by FBO |
| glClearColor | Clear color (used by glClear) |
| glViewport | Viewport, used when drawing |
| glScissor | Scissor, used when drawing |
| glDepthFunc | Depth function |
| glStencilFunc | Stencil function |
| glGenVertexArrays | Nothing. |
| glBindVertexArray | VAO |
| glGenBuffers | Nothing. |
| glBindBuffer | VBO; if binding GL_ELEMENT_ARRAY_BUFFER, also affects VAO |
| glBufferData | VBO |
| glVertexAttribPointer | VAO, VBO (current VBO is now pointed to by VAO) |
| glEnableVertexAttribArray | VAO |
| glDisableVertexAttribArray | VAO |
| glCreateShader | Nothing, the shader functions all tell which shader/program to use. |
| glShaderSource | Nothing. |
| glCompileShader | Nothing. |
| glDetachShader | Nothing. |
| glDeleteShader | Nothing. |
| glCreateProgram | Nothing. |
| glAttachShader | Nothing. |
| glLinkProgram | Nothing. |
| glUseProgram | Shader program |
| glGetUniformLocation | Nothing |
| glUniform* | I think uniforms are part of the shader program? |
| glGenTextures | Nothing. |
| glBindTexture | Texture |
| glTexImage* | Texture |
| glTexSubImage* | Texture |
| glTexParameter* | Texture |
| glGenerateMipmap | Texture |
| glActiveTexture | Texture unit (also changes current texture) |
| glGenFramebuffers | Nothing. |
| glBindFramebuffer | FBO |
| glDeleteFramebuffers | Nothing. |
| glCheckFramebufferStatus | FBO |
| glFramebufferTexture2D | FBO |
| glGenRenderbuffers | RBO |
| glBindRenderbuffer | RBO |
| glRenderbufferStorage | RBO |
| glFramebufferRenderbuffer | FBO (also takes an RBO argument) |
| glDrawArrays | See 'Used when drawing?' columns |
| glDrawElements | See 'Used when drawing?' columns |