Parse L-system config files

 - Added support for parsing config files, and an example config. The
   config isn't used for anything yet. (That's coming next.)

 - Otherwise, this should behave as normal.

Makefile

@@ -17,12 +17,17 @@ l_system_mesh.o: l_system_mesh.c l_system_mesh.h utilities.h
 turtle_3d.o: turtle_3d.c turtle_3d.h
 	gcc $(CFLAGS) -c -o turtle_3d.o turtle_3d.c -I cglm/include
 
-l_system_3d: l_system_3d.c l_system_mesh.o turtle_3d.o utilities.o
+parse_config.o: parse_config.c parse_config.h turtle_3d.h
+	gcc $(CFLAGS) -c -o parse_config.o parse_config.c
+
+l_system_3d: l_system_3d.c l_system_mesh.o turtle_3d.o utilities.o \
+	parse_config.o
 	gcc $(CFLAGS) -o l_system_3d l_system_3d.c \
 		glad/src/glad.c \
 		utilities.o \
 		l_system_mesh.o \
 		turtle_3d.o \
+		parse_config.o \
 		-I glad/include \
 		-I cglm/include \
 		$(GLFW_CFLAGS)

README.md

@@ -3,3 +3,116 @@
 
 I will write a README when the project is done.
 
+Configuring the L-System
+========================
+
+The system reads its configuration from the "config.txt" file.  The file
+must contain only ASCII characters. It starts with the L-system definition
+(replacement rules). Following a line containing the keyword `actions`, the
+file switches to defining the drawing actions the "turtle" takes when
+encountering each character. (The `actions` line must occur exactly once in the
+config.)
+
+If you want a longer example, the default "config.txt" contains instructions
+for drawing the dragon curve, and is shown below:
+```
+init F
+F F+G
+G F-G
+
+actions
+F
+move_forward 1.0
+G
+move_forward 1.0
+-
+rotate -90.0
++
+rotate 90.0
+```
+
+Any lines starting with `#` in the config file are ignored. So, in addition to
+L-system characters being limited to ASCII, non-printing, whitespace
+characters, and the `#` character are not allowed in replacement rules. Note
+that the `#` must be the first non-whitespace character in the line.
+
+Replacement Rules
+-----------------
+
+The first part of the config defines the replacement rules. This section of
+the file ends when the line containing the word `actions` is encountered.
+Exactly one line in this part of the file must give the initial contents of the
+L-system string:
+
+ - `init <initial text>`
+
+All other non-blank and non-comment lines in this section take the following
+format:
+
+ - `<character> <string of replacement characters>`
+
+The character is separated from the string of replacements by one or more tab
+or space characters.
+
+Characters with no defined replacement rules are left as-is during L-system
+iteration. Any line containing a character with no following replacement text
+indicates that the character is to be deleted when encountered (i.e. replaced
+with a blank string).
+
+Each character can have at most one replacement rule.
+
+Action Rules
+------------
+
+Following the `actions` line, the config switches to defining what each
+character means for drawing the graphics. Actions for a character are defined
+as follows:
+
+```
+<character>
+<action 1>
+<action 2>
+...
+<action n>
+```
+
+In other words, the character must first appear on a line by itself. The
+following lines must contain the arbitrary number of actions to be taken when
+the character is processed. The list of actions ends when either the end of the
+file is reached or another line containing a single character is reached. (Note
+that none of the actions are a single character long, so there is no ambiguity
+between lines containing a single character and lines containing an action.)
+
+Each character is allowed at most one associated sequence of actions. Any
+character that does not appear in the actions section prompts no drawing
+actions when rendering the L-system. (This can also be achieved by including
+a character in the actions section, but not specifying any actions after it.)
+
+Available Actions
+-----------------
+
+The following list of actions are supported:
+
+ - `move_forward <distance>`: Moves the turtle forward, drawing a line, the
+   given distance. The distance is a floating-point number of units. Units are
+   not particularly relevant, because the resulting 3D rendering will be scaled
+   to fit in the viewport regardless.
+
+ - `rotate <degrees>`: Rotates the turtle to its left by the given
+   floating-point number of degrees.
+
+ - `yaw <degrees>`: The same as the `rotate` action.
+
+ - `pitch <degrees>`: Rotates the turtle in the upwards direction by the given
+    floating-point number of degrees.
+
+ - `roll <degrees>`: Rotates the turtle by the given number of degrees about
+   its forward-facing axis.
+
+ - `move_forward_nodraw <distance>`: Like `move_forward`, but does not draw a
+   line segment.
+
+Prior to taking any actions, the turtle is initialized at position (0, 0, 0),
+facing in the positive-X direction, with its pitch and roll set so that its
+"back" is facing upwards; in the positive-Y direction.
+

build_windows.bat

@@ -2,6 +2,7 @@ gcc -Wall -Werror -O3 -o l_system_3d ^
   l_system_3d.c ^
   l_system_mesh.c ^
   turtle_3d.c ^
+  parse_config.c ^
   utilities.c ^
   glad\src\glad.c ^
   -I cglm\include ^

config.txt

@@ -0,0 +1,20 @@
+# Draw a dragon curve.
+init F
+F F+G
+G F-G
+
+actions
+
+F
+move_forward 1.0
+
+G
+move_forward 1.0
+
+-
+rotate -90.0
+
++
+# Comments can go anywhere, so long as the '#' is at the start of the line.
+rotate 90.0
+

l_system_3d.c

@@ -6,13 +6,13 @@
 #include <glad/glad.h>
 #include <GLFW/glfw3.h>
 #include "l_system_mesh.h"
+#include "parse_config.h"
 #include "turtle_3d.h"
 #include "utilities.h"
 #include "l_system_3d.h"
 
 #define DEFAULT_WINDOW_WIDTH (800)
 #define DEFAULT_WINDOW_HEIGHT (600)
-#define PI (3.1415926536)
 
 ApplicationState* AllocateApplicationState(void) {
   ApplicationState *to_return = NULL;
@@ -29,6 +29,7 @@ void FreeApplicationState(ApplicationState *s) {
   if (!s) return;
   if (s->mesh) DestroyLSystemMesh(s->mesh);
   if (s->turtle) DestroyTurtle3D(s->turtle);
+  if (s->config) DestroyLSystemConfig(s->config);
   glDeleteBuffers(1, &(s->ubo));
   if (s->window) glfwDestroyWindow(s->window);
   memset(s, 0, sizeof(*s));
@@ -85,7 +86,7 @@ static int SetupUniformBuffer(ApplicationState *s) {
 }
 
 static int Rotate90(Turtle3D *t) {
-  return RotateTurtle(t, PI * 0.5);
+  return RotateTurtle(t, 90);
 }
 
 // This generates the vertices for the L-system, and updates the mesh. Returns
@@ -108,7 +109,7 @@ static int GenerateVertices(ApplicationState *s) {
   t->color[0] = 1;
   t->color[1] = 1;
   if (!MoveTurtleForward(t, 1.0)) return 0;
-  if (!PitchTurtle(t, PI * 0.5)) return 0;
+  if (!PitchTurtle(t, 90)) return 0;
   t->color[0] = 0.7;
   t->color[1] = 0.1;
   if (!MoveTurtleForward(t, 0.5)) return 0;
@@ -219,6 +220,19 @@ int main(int argc, char **argv) {
     to_return = 1;
     goto cleanup;
   }
+  s->config = LoadLSystemConfig("./config.txt");
+  if (!s->config) {
+    printf("Error parsing ./config.txt.\n");
+    to_return = 1;
+    goto cleanup;
+  }
+  printf("Config loaded OK!\n");
+  // TODO: Create the actual L-system
+  //  - Parse the config file
+  //    - If the config file is faulty, then display some basic test model, to
+  //      avoid closing the program if someone mistakenly reloads a bad config.
+  //  - Iterate the string. Create an LSystem type, probably.
+  //  - Make the turtle follow the rules.
   if (!GenerateVertices(s)) {
     printf("Failed generating vertices.\n");
     to_return = 1;

l_system_3d.h

@@ -2,6 +2,7 @@
 #include <cglm/cglm.h>
 #include <glad/glad.h>
 #include "l_system_mesh.h"
+#include "parse_config.h"
 #include "turtle_3d.h"
 
 // Uniforms shared with all shaders. Must match the layout in
@@ -19,6 +20,7 @@ typedef struct {
   int window_height;
   float aspect_ratio;
   LSystemMesh *mesh;
+  LSystemConfig *config;
   Turtle3D *turtle;
   GLuint ubo;
   SharedUniforms shared_uniforms;