Add readme

grogs/README.md

@@ -0,0 +1,59 @@
+# grogs (Ground graphics) library
+
+This library uses SDL3 to add graphics support to Ground.
+
+## Compiling
+
+First, ensure SDL3 is installed on your system. Then:
+
+```bash
+g++ -shared -fPIC -lSDL3 -o grogs.so grogs.cpp
+```
+
+## Functions
+
+### fun -int !initSDL -string &windowTitle -int &width -int &height
+
+This function initialises SDL for use in Grogs. **This must be run before trying to run any other Grogs functions!**
+
+First argument is the window title, second and third are width and height of the window, respectively.
+
+If everything goes fine, returns 0.
+
+If SDL couldn't create the window, returns 1. If already initialized, returns 2.
+
+Example:
+
+```
+pusharg "My Awesome Window" 640 480
+!grogs:initSDL &result
+```
+
+### fun -int !pollEvent
+
+Returns a code for an event that has been polled. For now, only window closing is supported, which will return 0. Anything else for now will return -1.
+
+### fun -int !clearRenderer
+
+Clears the renderer of any pixels to be rendered. Returns 0, unless SDL is not initialized.
+
+### fun -int !renderFrame
+
+Renders frame on the screen. Whichever pixels have been set will be displayed. Returns 0, unless SDL is not initialized.
+
+### fun -int !setPixel -int &xpos -int &ypos -int &red -int &green -int &blue
+
+Sets a pixel at the desired location to the desired colour. Returns 0, unless SDL is not initialized.
+
+First argument: xpos
+Second argument: ypos
+Third argument: red value (0 to 255)
+Fourth argument: green value (0 to 255)
+Fifth argument: blue value (0 to 255)
+
+This example sets the pixel at (10, 10) to white (RGB(255, 255, 255)):
+
+```
+pusharg 10 10 255 255 255
+call !grogs:setPixel &result
+```

grogs/grogs.cpp

@@ -57,7 +57,7 @@ GroundValue renderFrame(GroundValue* args, int arg_count) {
         return GROUND_INT_VAL(-1);
     }
     SDL_RenderPresent(renderer);
-    return GROUND_BOOL_VAL(true);
+    return GROUND_INT_VAL(0);
 }
 
 GroundValue setPixel(GroundValue* args, int arg_count) {