SimplyRend

by: Wassimulator

Using OpenGL Version: 4.3
A simple lightweight immediate mode renderer for 2D graphics, written in C and OpenGL.
The approach is not the most efficient, but it's simple and it should work for small
scale indie purposes. The goal behind this is to help get the program up and running
quickly, while also setting up a foundation for expansion in features later.

"I hate doing this twice", well this is why I made this.

included libraries in package:

1 - emaths.h        - v1.0  by: Wassimulator
2 - stb_rect_pack   - v1.01 by: Sean Barrett
3 - stb_image       - v2.26 by: Sean Barrett
4 - stb_truetype    - v1.26 by: Sean Barrett

Important notes:

- Include OpenGL headers and load OpenGL functions with glad or otherwise before including this file, 
  here's a permalink to save you the trouble: https://glad.dav1d.de/#language=c&specification=gl&api=gl%3D4.3&api=gles1%3Dnone&api=gles2%3Dnone&api=glsc2%3Dnone&profile=compatibility&loader=on
- SymplyRend calls gladLoadGL() for you, you don't need to call it manually.
- Call SR_Init() before using any other functions.
- Call SR_StartFrame() at the beginning of each frame.
- SimplyRend does not create window contexts, the user should
  handle that with SDL, or otherwise.
- Use floating point color convention (0.0 to 1.0) for each value,
  otherwise use SR_Color_i(r, g, b, a) to convert to floating point colors.
- the first two shader programs are reserved for rendering basic shapes
  and textured quads.
- FrameWidth and FrameHeight are the draw logic size, not the window size.
  They are preferably set at the start and never changed during the program.
- WindowWidth and WindowHeight are the window size, they can be changed at any time.
  The distinction is there to allow for window resizing while maintaining relative
  positions.
- you need to handle displaying the frame, whether with SDL or otherwise, Window management
  is not included in SimplyRend.

Usage:

# relevant front end functions:
    - SR_Init()                     // initializes the library
    - SR_StartFrame()               // starts a new frame
    - SR_LoadFont()                 // loads a font
    - SR_LoadSprite()               // loads a sprite
    - SR_PackSpritesToTexture()     // generates a texture atlas out of a range of sprites
    - SR_PushSpriteRect()           // draws a sprite
    - SR_PushSpriteRectF()          // draws a sprite with floating point coordinates
    - SR_PushRect_Frame()           // draws a framed rectangle
    - SR_PushRect_Fill()            // draws a filled rectangle
    - SR_PushLine()                 // draws a two point line
    - SR_PushLines()                // draws a multiple point line
    - SR_PushText()                 // renders text
    - SR_PushRenderLayer()          // starts a new render layer
    - SR_Render()                   // renders the current frame using all collected data

     more info at functions definitions. Search for the names.

- Initialize SimplyRend with SR_Init()
- Before the game loop load all your sprites by declaring SR_Sprite* pointers
  and loading them with SR_LoadSprite() to generate sprite info and load to RAM.
- Use SR_PackSpritesToTexture() to pack a range of sprites into a single texture,
  be wary of hardware limitations, the function may not pack all sprites.
  You can use the function as many times as you want, even to pack single textures.
  The texture ID info will be stored in the sprite struct. But unless you plan on
  manipulating the behavior, you can ignore this.
- Load fonts at the start of the program with SR_LoadFont()
- Render functions buffer the render data in RAM; the render call sends it to the GPU at the end of the
  frame. Immediate mode.
  Render functions have multiple versions and can accept different parameters.

- custom shader creation is still in development.

All relative functions and structs start with the prefix "SR_" All Render related functions start with the prefix "SR_Push"

this is still a work in progress and bugs may occur, as features get added. It is in a running state though.