1 files changed, 48 insertions, 0 deletions
diff --git a/src/rtw/texture.zig b/src/rtw/texture.zig
index ae24265..95cbef4 100644
--- a/src/rtw/texture.zig
+++ b/src/rtw/texture.zig
@@ -1,4 +1,5 @@
 const std = @import("std");
+const Image = @import("zigimg").Image;
 
 const Color = @import("vec.zig").Color;
 const Vec3 = @import("vec.zig").Vec3;
@@ -10,12 +11,14 @@ const TextureTag = enum {
     solid,
     checker,
     noise,
+    image,
 };
 
 pub const Texture = union(TextureTag) {
     solid: SolidTexture,
     checker: CheckerTexture,
     noise: NoiseTexture,
+    image: ImageTexture,
 
     pub fn makeSolid(color: Color) Texture {
         return .{ .solid = .{ .color = color } };
@@ -33,11 +36,16 @@ pub const Texture = union(TextureTag) {
         return .{ .noise = try NoiseTexture.init(allocator, rng, scale) };
     }
 
+    pub fn makeImage(allocator: std.mem.Allocator, file_path: []const u8) !Texture {
+        return .{ .image = try ImageTexture.init(allocator, file_path) };
+    }
+
     pub fn value(tx: Texture, u: f64, v: f64, p: Vec3) Color {
         return switch (tx) {
             TextureTag.solid => |solidTx| solidTx.value(u, v, p),
             TextureTag.checker => |checkerTx| checkerTx.value(u, v, p),
             TextureTag.noise => |noiseTx| noiseTx.value(u, v, p),
+            TextureTag.image => |imageTx| imageTx.value(u, v, p),
         };
     }
 };
@@ -102,3 +110,43 @@ pub const NoiseTexture = struct {
         return rgb(1, 1, 1).mul(0.5 * (1.0 + @sin(tx.scale * p.z + 10.0 * tx.perlin.turb(p, 7))));
     }
 };
+
+pub const ImageTexture = struct {
+    image: Image,
+
+    fn init(allocator: std.mem.Allocator, file_path: []const u8) !ImageTexture {
+        const image = try Image.fromFilePath(allocator, file_path);
+        return .{
+            .image = image,
+        };
+    }
+
+    fn deinit(tx: ImageTexture) void {
+        tx.image.deinit();
+    }
+
+    fn value(tx: ImageTexture, u: f64, v: f64, p: Vec3) Color {
+        _ = p;
+        // Clamp input texture coordinates to [0, 1] x [1, 0]
+        const u_ = std.math.clamp(u, 0.0, 1.0);
+        const v_ = 1.0 - std.math.clamp(v, 0.0, 1.0); // Flip v to image coordinates
+        const i = @floatToInt(usize, u_ * @intToFloat(f64, tx.image.width));
+        const j = @floatToInt(usize, v_ * @intToFloat(f64, tx.image.height));
+        // Clamp integer mapping, since actual coordinates should be less than 1.0
+        const i_ = @min(i, tx.image.width - 1);
+        const j_ = @min(j, tx.image.width - 1);
+        const color_scale = 1.0 / 255.0;
+        const pixels = tx.image.pixels.asBytes();
+        const offset = j_ * tx.image.width * 4 + i_ * 4;
+        const r = @intToFloat(f64, pixels[offset + 0]);
+        const g = @intToFloat(f64, pixels[offset + 1]);
+        const b = @intToFloat(f64, pixels[offset + 2]);
+        const a = @intToFloat(f64, pixels[offset + 3]);
+        if (a == 0) {
+            // Ocean
+            return rgb(0, 0, 1.0);
+        } else {
+            return rgb(color_scale * r, color_scale * g, color_scale * b);
+        }
+    }
+};