From de3c9942416382aae0f2f2aac3b67c1e8b4d71f1 Mon Sep 17 00:00:00 2001
From: Aaditya Dhruv <aadityadhruv@mailbox.org>
Date: Tue, 27 Jan 2026 20:10:55 -0600
Subject: Add support for chunk and world

- Chunk is a array of blocks
- World is a array of chunks
- Basic chunk plains generation based on simple linear functions
- Bunch of functions still not implemented, in design phase
---
 src/chunk.c | 107 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 107 insertions(+)
 create mode 100644 src/chunk.c

(limited to 'src/chunk.c')

diff --git a/src/chunk.c b/src/chunk.c
new file mode 100644
index 0000000..77c2301
--- /dev/null
+++ b/src/chunk.c
@@ -0,0 +1,107 @@
+#include "chunk.h"
+#include "block.h"
+#include "cglm/io.h"
+#include "cglm/util.h"
+#include "cglm/vec2.h"
+#include "cglm/vec3.h"
+#include "world.h"
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+
+#define MIN(x, y) (x < y) ? x : y
+#define MAX(x, y) (x > y) ? x : y
+
+void _chunk_plains_gen(struct chunk* chunk);
+
+int chunk_gen(struct world* world, struct chunk *chunk) {
+    // struct chunk neighbor = {0};
+    // world_get_chunk(world, chunk->coord, &neighbor);
+    _chunk_plains_gen(chunk);
+    // switch (chunk->biome) {
+    //     case JUNK_BIOME_PLAINS:
+    //         _
+    //         break;
+    //     default:
+    //         break;
+    // }
+    return 0;
+}
+
+float _chunk_plains_get_z(vec2 target, vec3 poi, float m, int base_z) {
+    vec2 unit = { (target[0] - poi[0]), (target[1] - poi[1]) };
+    glm_vec2_normalize(unit);
+    // Line direction vector
+    vec3 r = { unit[0], unit[1], m };
+    // r*t + poi = { x, y, z }, solve first for t, then get z
+    float t = 0;
+    // Parallel to X-axis
+    if (r[0] == 0.0f && r[1] != 0.0f) {
+        t = (target[1] - poi[1]) / r[1];
+    }
+    // Parallel to Y-axis
+    else if (r[1] == 0.0f && r[0] != 0.0f) {
+        t = (target[0] - poi[0]) / r[0];
+    }
+    else if (r[0] != 0.0f && r[1] != 0.0f) {
+        // Non-parallel line, either X or y works
+        t = (target[0] - poi[0]) / r[0];
+    }
+    else {
+        //Else we are POI itself, no need to do anything. t will be zero and
+        //the value of z == poi[2]. We subtract -1 from base_z because
+        //otherwise the POI will be a single block at it's z, all others will
+        //always be strictly less than it. This levels the plains
+        base_z -= 1;
+    }
+    float z_off = poi[2] + t * r[2];
+
+    return MAX(base_z, base_z + z_off);
+}
+
+/**
+ * Basic Plains chunk generation
+ * Algorithm: Pick 2 points of interest (POI). These points will either be elevations or depressions.
+ * Each block will get a invisible "offset" value based on their distance from the chosen point.
+ * Chosen point height itself will range from some non zero value to another, plus in negative.
+ * The offset value determines how block heights are created
+ *
+ */
+void _chunk_plains_gen(struct chunk* chunk) {
+    // ============ KNOBS ============
+    // Minimum ground
+    int z = 2;
+    // Min POI block height
+    int poi_min = 3;
+    // Max POI block height
+    int poi_max = 5;
+    // Descent/Ascent rate
+    float m = -.5;
+    memset(chunk->blocks, 0, CHUNK_HEIGHT * CHUNK_LENGTH * CHUNK_WIDTH * sizeof(struct block*));
+    // X, Y, POI Height
+    vec3 poi1 = { rand() % CHUNK_WIDTH, rand() % CHUNK_LENGTH, poi_min + (rand() % (poi_max - poi_min))};
+    vec3 poi2 = { rand() % CHUNK_WIDTH, rand() % CHUNK_LENGTH, -poi_min + (rand() % (poi_max - poi_min))};
+    
+    for (int x = 0; x < CHUNK_LENGTH; x++) {
+        for (int y = 0; y < CHUNK_WIDTH; y++) {
+            // Minimum z height
+            // Interpolation formula - simple linear
+            vec2 target = { x, y };
+            float z1 = _chunk_plains_get_z(target, poi1, m, z);
+            float z2 = _chunk_plains_get_z(target, poi2, -m, z);
+            int z_final = (z1 + z2) / 2;
+            for (int h = 0; h < z_final; h++) {
+                struct block* blk = malloc(sizeof(struct block));
+                vec3 pos = {x, h, -y - 1};
+                block_init(pos, blk);
+                chunk->blocks[x][y][h] = blk;
+            }
+        }
+    }
+    fprintf(stderr, "POI Coords\n");
+    glm_vec3_print(poi1, stderr);
+    glm_vec3_print(poi2, stderr);
+}
-- 
cgit