Initial commit: placing pieces

1 files changed, 75 insertions, 0 deletions

diff --git a/pieces.c b/pieces.c
new file mode 100644
index 0000000..95c9923
--- /dev/null
+++ b/pieces.c
@@ -0,0 +1,75 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "pieces.h"
+
+const int N_SHAPES = 17;
+const struct piece SHAPES[] = {
+    {1, 1, "+"},
+    {1, 2, "++"},
+    {1, 3, "+++"},
+    {1, 4, "++++"},
+    {1, 5, "+++++"},
+    {2, 2, "+  +"},         // 2x2 diagonal
+    {2, 2, "++++"},         // 2x2 square
+    {2, 3, "++++  "},       // L shape
+    {2, 3, "++  ++"},       // Z shape
+    {2, 3, "+++ + "},       // T shape
+    {2, 3, "++++++"},       // 2x3 rectangle
+    {2, 4, "+++++   "},     // long L shape
+    {2, 4, "++++++++"},     // 2x4 rectangle
+    {3, 3, "++++  +  "},    // large L shape
+    {3, 3, "+++ +  + "},    // large T shape
+    {3, 3, "+   +   +"},    // 3x3 diagonal
+    {3, 3, "+++++++++"},    // 3x3 square
+};
+
+void transpose(struct piece* pc) {
+    // transpose blocks
+    char* old = malloc(strlen(pc->blocks) + 1);
+    strcpy(old, pc->blocks); // before transposition
+    for (int r = 0; r < pc->h; r++) {
+        for (int c = 0; c < pc->w; c++) {
+            pc->blocks[c * (pc->h) + r] = old[r * (pc->w) + c];
+        }
+    }
+    free(old);
+    // swap dimensions
+    int h = pc->h;
+    pc->h = pc->w;
+    pc->w = h;
+}
+
+void rotate(struct piece* pc) {
+    // rotate `pc` ccw by 90 degrees
+    // transpose blocks
+    char* old = malloc(strlen(pc->blocks) + 1);
+    strcpy(old, pc->blocks); // before transposition
+    for (int r = 0; r < pc->h; r++) {
+        for (int c = 0; c < pc->w; c++) {
+            pc->blocks[(pc->w - c - 1) * (pc->h) + r] = old[r * (pc->w) + c];
+        }
+    }
+    free(old);
+    // swap dimensions
+    int h = pc->h;
+    pc->h = pc->w;
+    pc->w = h;
+}
+
+struct piece* randpiece() {
+    // select a random shape from `SHAPES`, make a copy where memory for `.blocks` is manually managed,
+    // then do random transformations to the copy
+    struct piece shape = SHAPES[rand() % N_SHAPES];
+    char* blocks = malloc(strlen(shape.blocks) + 1);
+    strcpy(blocks, shape.blocks);
+    struct piece* pc = malloc(sizeof(struct piece));
+    pc->h = shape.h;
+    pc->w = shape.w;
+    pc->blocks = blocks;
+    if (rand() % 2) transpose(pc);
+    for (int i = rand() % 4; i > 0; i--) // 0 to 3 times
+        rotate(pc);
+    return pc;
+}
+