Replace example with Sierpinski pyramid

 - Changed the included config.txt to show a multi-colored Sierpinski
   pyramid.

 - Increased the model's scale, and changed the camera some.

README.md

@@ -54,7 +54,7 @@ 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 a pair of connected dragon curves. A simpler, single, dragon-curve
+for drawing a multi-colored Sierpinski pyramid. A simpler, single, dragon-curve
 example can be obtained by replacing the contents of "config.txt" with the
 following lines:
 ```

config.txt

@@ -1,40 +1,105 @@
-# Draw two connected dragon curves.
-# P = set the initial color to purple.
-# F = draw a dragon curve
-# R = rotate and change color
-init PFRF
+init CP
 
-F F+G
-G F-G
+# The () around the pyramids make it easier for me to keep track of the
+# positions when moving between the 5 pyramids.
+
+# Replace one square pyramid with 5 pyramids, always ending at the bottom left
+# corner facing right.
+P ((CPN1PN-N2PN-N3P)UND4P)
+N NN
 
 actions
 
-P
-# Set color to purple.
+# C, 1, 2, 3, and 4 all just set colors. You can remove them from the
+# replacement string to simplify it if you want.
+C
 set_color_r 0.7
-set_color_g 0.2
+set_color_g 0.3
 set_color_b 1.0
 
-B
-set_turtle_B
+1
+set_color_r 1.0
+set_color_g 0.2
+set_color_b 0.2
 
-F
-move_forward 1.0
+2
+set_color_r 0.2
+set_color_g 1.0
+set_color_b 0.2
 
-G
-move_forward 1.0
+3
+set_color_r 0.2
+set_color_g 0.2
+set_color_b 1.0
+
+4
+set_color_r 1.0
+set_color_g 1.0
+set_color_b 1.0
 
 -
-rotate -90.0
+rotate 90
 
-R
-pitch 90.0
-# Set color to a bright-ish green.
-set_color_r 0.2
-set_color_g 0.9
-set_color_b 0.2
+(
+push_position 0.0
+
+)
+pop_position 0.0
+
+N
+move_forward_nodraw 1.0
+
+# Face "upwards" to move to the upper pyramid.
+U
+rotate 45
+pitch 45
+
+# Undo the "upwards rotation in preparation for drawing the upper pyramid.
+D
+pitch -45
+rotate -45
+
+
+# P = draw a single square pyramid. Starts at the bottom left corner facing
+# right, and ending at the bottom right corner, facing right.
+P
+
+# Keep track of our start position, we'll return here at the end.
+push_position 0
+
+# Bottom left -> bottom right, up edge from bottom right
+move_forward 1
+push_position 0
+rotate 135
+pitch 45
+move_forward 1
+pop_position 0
+
+# Bottom right -> up right, up edge from up right
+rotate 90
+move_forward 1
+push_position 0
+rotate 135
+pitch 45
+move_forward 1
+pop_position 0
+
+# up right -> up left, up edge from up left
+rotate 90
+move_forward 1
+push_position 0
+rotate 135
+pitch 45
+move_forward 1
+pop_position 0
+
+# up left -> bottom left, up edge from bottom left
+rotate 90
+move_forward 1
+rotate 135
+pitch 45
+move_forward 1
 
-+
-# Comments can go anywhere, so long as the '#' is at the start of the line.
-rotate 90.0
+# Return to bottom left, facing right.
+pop_position 0
 

l_system_3d.c

@@ -267,9 +267,9 @@ static void UpdateCamera(ApplicationState *s) {
   glm_vec3_zero(up);
   up[1] = 1.0;
   tmp = glfwGetTime() / 4.0;
-  position[0] = sin(tmp) * 4.0;
-  position[1] = 3.0;
-  position[2] = cos(tmp) * 4.0;
+  position[0] = sin(tmp) * 5.0;
+  position[1] = 2.0;
+  position[2] = cos(tmp) * 5.0;
   glm_lookat(position, target, up, s->shared_uniforms.view);
   glm_vec4(position, 0, s->shared_uniforms.camera_position);
 }

turtle_3d.c

@@ -123,7 +123,7 @@ int SetTransformInfo(Turtle3D *t, mat4 model, mat3 normal, vec3 loc_offset) {
   max_axis = Max3(dx, dy, dz);
   glm_mat4_identity(model);
   if (max_axis > 0) {
-    glm_scale_uni(model, 2.0 / max_axis);
+    glm_scale_uni(model, MESH_CUBE_SIZE / max_axis);
   }
   ModelToNormalMatrix(model, normal);
   // TODO (eventually): If I get less stupid, combine the loc_offset

turtle_3d.h

@@ -4,6 +4,10 @@
 #include <stdint.h>
 #include "l_system_mesh.h"
 
+// The length per edge of the centered cube that the turtle's resulting mesh
+// is scaled to fit into.
+#define MESH_CUBE_SIZE (4.0)
+
 // Holds the turtle's position and orientation information.
 typedef struct {
   // The turtle's current location.