Variable height walls!

1 files changed, 17 insertions, 9 deletions

diff --git a/src/main.zig b/src/main.zig
index e912b5f..64da425 100755..100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -1,4 +1,4 @@
-//  ZiRC, a Zig raycaster for fun
+// ZiRC, a Zig raycaster for fun
 //
 // Copyright (C) 2021, tslil clingman
 //
@@ -31,25 +31,33 @@ usingnamespace @import("map.zig");
 const screenWidth = 1280;
 const screenHeight = 960;
 
+// TODO: is there anyway i can say fn renderWall : RenderWallFunction?
 fn renderWall(
     window: sf.graphics.RenderWindow,
     sprite: sf.graphics.Sprite,
     col: i32, // which column
     top: f32, // top of wall
-    height: f32, // how tall
+    total_height: f32, // how tall
+    draw_frac: f32,
     texfrac: f32, // how far along the texture
     texture: u8, // which texture index
-) !void {
+) void {
     const hFact = screenWidth / planeWidth;
     const vFact = screenHeight / planeHeight;
+
+    // we need ceil here so that we draw always to or past the edge of the screen
+    const draw_height = @floatToInt(c_int, std.math.ceil(draw_frac * wallTextureDim));
+    const total_length = total_height * vFact;
+
     const xpos = @intToFloat(f32, col) * hFact;
-    const length = height * vFact;
-    const starty = (screenHeight + vFact * planeHeight) / 2 - top * vFact;
+    const ypos = (screenHeight + vFact * planeHeight) / 2 - top * vFact;
+
     const tind = @as(c_int, texture) * @floatToInt(c_int, 1 + wallTextureDim);
+    const left = tind + @floatToInt(c_int, texfrac * wallTextureDim);
 
-    sprite.setPosition(.{ .x = xpos, .y = starty });
-    sprite.setScale(.{ .x = hFact, .y = length / wallTextureDim });
-    sprite.setTextureRect(.{ .top = 0, .left = tind + @floatToInt(c_int, texfrac * wallTextureDim), .width = 1, .height = wallTextureDim });
+    sprite.setPosition(.{ .x = xpos, .y = ypos });
+    sprite.setScale(.{ .x = hFact, .y = total_length / wallTextureDim });
+    sprite.setTextureRect(.{ .top = 0, .left = left, .width = 1, .height = draw_height });
     window.draw(sprite, null);
 }
 
@@ -165,7 +173,7 @@ pub fn main() !void {
         });
         window.draw(backSprite, null);
 
-        try player.renderMapUsing(window, wallSprite, map, renderWall);
+        player.renderMapUsing(window, wallSprite, map, renderWall);
 
         window.display();