From 5dbdf9351a065a821938c9cc123988a236fd417b Mon Sep 17 00:00:00 2001
From: Marcus Ramse <marcus@ramse.se>
Date: Mon, 20 May 2024 01:14:12 +0200
Subject: [PATCH] sim: fix colors (flipping all over)

---
 simulator/src/compositor.ts  | 18 +++++++++++++++---
 simulator/src/framebuffer.ts | 14 +++++++-------
 simulator/src/ui/utils.ts    |  6 ++++--
 3 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/simulator/src/compositor.ts b/simulator/src/compositor.ts
index aa157bf..ddf86e8 100644
--- a/simulator/src/compositor.ts
+++ b/simulator/src/compositor.ts
@@ -3,6 +3,8 @@ import * as GL from "./webgl-constants";
 import type { Framebuffer } from "./framebuffer";
 
 export class WebGLCompositor {
+    flipped = new Uint16Array(WIDTH * HEIGHT);
+
     constructor (public gl: WebGLRenderingContext) {
         const canvas = gl.canvas;
         canvas.addEventListener("webglcontextlost", event => {
@@ -63,7 +65,7 @@ export class WebGLCompositor {
             varying vec2 framebufferCoord;
 
             void main () {
-                gl_FragColor = texture2D(framebuffer, vec2(framebufferCoord.y, framebufferCoord.x));
+                gl_FragColor = texture2D(framebuffer, framebufferCoord);
             }
         `);
 
@@ -88,7 +90,7 @@ export class WebGLCompositor {
 
         // Create framebuffer texture
         createTexture(GL.TEXTURE0);
-        gl.texImage2D(GL.TEXTURE_2D, 0, GL.RGB565, HEIGHT, WIDTH, 0, GL.RGB, GL.UNSIGNED_SHORT_5_6_5, null);
+        gl.texImage2D(GL.TEXTURE_2D, 0, GL.RGB565, WIDTH, HEIGHT, 0, GL.RGB, GL.UNSIGNED_SHORT_5_6_5, null);
 
         // Setup static geometry
         const positionAttrib = gl.getAttribLocation(program, "pos");
@@ -107,8 +109,18 @@ export class WebGLCompositor {
         const gl = this.gl;
         const bytes = framebuffer.bytes;
 
+        // Rotate and swap byte order flip bytes
+        // Would not be required if WebGL supported `UNSIGNED_SHORT_5_6_5_REV`
+        for (let x = 0; x < WIDTH; x++) {
+            for (let y = 0; y < HEIGHT; y++) {
+                const fi = x + y * WIDTH;
+                const bi = x * HEIGHT + y;
+                this.flipped[fi] = ((bytes[bi] & 0xff) << 8) | (bytes[bi] >> 8);
+            }
+        }
+
         // Upload framebuffer
-        gl.texImage2D(GL.TEXTURE_2D, 0, GL.RGB565, HEIGHT, WIDTH, 0, GL.RGB, GL.UNSIGNED_SHORT_5_6_5, bytes);
+        gl.texImage2D(GL.TEXTURE_2D, 0, GL.RGB565, WIDTH, HEIGHT, 0, GL.RGB, GL.UNSIGNED_SHORT_5_6_5, this.flipped);
 
         // Draw the fullscreen quad
         gl.drawArrays(GL.TRIANGLES, 0, 6);
diff --git a/simulator/src/framebuffer.ts b/simulator/src/framebuffer.ts
index 9dd04f7..27c0164 100644
--- a/simulator/src/framebuffer.ts
+++ b/simulator/src/framebuffer.ts
@@ -28,7 +28,7 @@ export class Framebuffer {
     }
 
     drawHLine(color: number, x: number, y: number, len: number) {
-        if (y + len <= 0 || x < 0 || x >= WIDTH) {
+        if (x + len <= 0 || y < 0 || y >= HEIGHT) {
             return;
         }
 
@@ -36,7 +36,7 @@ export class Framebuffer {
         const endX = Math.min(WIDTH, x + len);
 
         for (let xx = startX; xx < endX; xx++) {
-            this.drawPoint(color, xx, y);
+            this.drawPointUnclipped(color, xx, y);
         }
     }
 
@@ -67,7 +67,7 @@ export class Framebuffer {
 
         if (fillColor !== OPTIONAL_COLOR_NONE) {
             for (let yy = startY; yy < endY; ++yy) {
-                this.drawHLine(fillColor, startX, yy, endX);
+                this.drawHLine(fillColor, startX, yy, endX - startX);
             }
         }
 
@@ -88,12 +88,12 @@ export class Framebuffer {
 
             // Top edge
             if (y >= 0 && y < HEIGHT) {
-                this.drawHLine(strokeColor, startX, y, endX);
+                this.drawHLine(strokeColor, startX, y, endX - startX);
             }
 
             // Bottom edge
             if (endYUnclamped > 0 && endYUnclamped <= HEIGHT) {
-                this.drawHLine(strokeColor, startX, endYUnclamped - 1, endX);
+                this.drawHLine(strokeColor, startX, endYUnclamped - 1, endX - startX);
             }
         }
     }
@@ -151,8 +151,8 @@ export class Framebuffer {
             const len = east - start;
 
             if (fillColor !== OPTIONAL_COLOR_NONE && len > 0) { // Only draw fill if the length from west to east is not 0
-                this.drawHLine(fillColor, start, north, east); /*   I and III. Quadrant */
-                this.drawHLine(fillColor, start, south, east); /*  II and IV. Quadrant */
+                this.drawHLine(fillColor, start, north, east - start); /*   I and III. Quadrant */
+                this.drawHLine(fillColor, start, south, east - start); /*  II and IV. Quadrant */
             }
 
             const err2 = 2 * err;
diff --git a/simulator/src/ui/utils.ts b/simulator/src/ui/utils.ts
index 1b4f888..618aae3 100644
--- a/simulator/src/ui/utils.ts
+++ b/simulator/src/ui/utils.ts
@@ -44,11 +44,13 @@ export function requestFullscreen () {
  * @returns RGB565 representation
  */
 export function pack565(red: number, green: number, blue: number): number {
-    return blue | (green << 5) | (red << 11);
+    const rev = blue | (green << 5) | (red << 11);
+    return ((rev & 0xff) << 8) | (rev >> 8);
 }
 
 export function unpack565(bgr565: number): [number, number, number] {
-    return [bgr565 >> 11, bgr565 >> 5 & 0b111111, bgr565 & 0b11111];
+    const flipped = ((bgr565 & 0xff) << 8) | (bgr565 >> 8);
+    return [flipped >> 11, flipped >> 5 & 0b111111, flipped & 0b11111];
 }
 
 export function unpack888(bgr888: number): [number, number, number] {