transition: Add Checkers transition

Signed-off-by: Javiya Vivekkumar Dineshbhai <vivek.javiya@collabora.com>
Change-Id: Ia1e88336309974606d0213a8e9c302995a4b1590

3 files changed, 99 insertions, 0 deletions

diff --git a/browser/Makefile.am b/browser/Makefile.am
index 3699fcb1b5..80ca287042 100644
--- a/browser/Makefile.am
+++ b/browser/Makefile.am
@@ -414,6 +414,7 @@ COOL_JS_LST =\
 	src/slideshow/Transition2d.ts \
 	src/slideshow/PerformTransition.ts \
 	src/slideshow/transition/FadeTransition.ts \
+	src/slideshow/transition/CheckersTransition.ts \
 	src/slideshow/transition/BarsTransition.ts \
 	src/slideshow/transition/WheelTransition.ts \
 	src/slideshow/transition/UncoverTransition.ts \
@@ -854,6 +855,7 @@ pot:
 		src/slideshow/Transition2d.ts \
 		src/slideshow/PerformTransition.ts \
 		src/slideshow/transition/FadeTransition.ts \
+		src/slideshow/transition/CheckersTransition.ts \
 		src/slideshow/transition/BarsTransition.ts \
 		src/slideshow/transition/WheelTransition.ts \
 		src/slideshow/transition/UncoverTransition.ts \
diff --git a/browser/src/slideshow/PerformTransition.ts b/browser/src/slideshow/PerformTransition.ts
index 8d7a8e6396..c855e4003c 100644
--- a/browser/src/slideshow/PerformTransition.ts
+++ b/browser/src/slideshow/PerformTransition.ts
@@ -55,6 +55,15 @@ SlideShow.PerformTransition = function (
                 image2,
             ).start(1);
             break;
+        
+        case 'CHECKERS':
+            new CheckersTransition(
+                canvas,
+                image1,
+                image2,
+            ).start(1);
+            break;
+
         default:
             console.error('Unknown transition type');
             break;
diff --git a/browser/src/slideshow/transition/CheckersTransition.ts b/browser/src/slideshow/transition/CheckersTransition.ts
new file mode 100644
index 0000000000..0df488ff9b
--- /dev/null
+++ b/browser/src/slideshow/transition/CheckersTransition.ts
@@ -0,0 +1,88 @@
+/*
+ * Copyright the Collabora Online contributors.
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+class CheckersTransition extends Transition2d {
+	private direction: number = 0;
+	constructor(
+		canvas: HTMLCanvasElement,
+		image1: HTMLImageElement,
+		image2: HTMLImageElement,
+	) {
+		super(canvas, image1, image2);
+		this.prepareTransition();
+		this.animationTime = 1500;
+	}
+
+	public renderUniformValue(): void {
+		this.gl.uniform1i(
+			this.gl.getUniformLocation(this.program, 'direction'),
+			this.direction,
+		);
+	}
+
+	public start(direction: number): void {
+		this.direction = direction;
+		this.startTransition();
+	}
+
+	public getVertexShader(): string {
+		return `#version 300 es
+				in vec4 a_position;
+				in vec2 a_texCoord;
+				out vec2 v_texCoord;
+
+				void main() {
+					gl_Position = a_position;
+					v_texCoord = a_texCoord;
+				}
+				`;
+	}
+
+	public getFragmentShader(): string {
+		return `#version 300 es
+                precision mediump float;
+
+                uniform sampler2D leavingSlideTexture;
+                uniform sampler2D enteringSlideTexture;
+                uniform float time;
+                uniform int direction; // 1 for vertical, 2 for horizontal
+
+                in vec2 v_texCoord;
+                out vec4 outColor;
+
+                void main() {
+                    vec2 uv = v_texCoord;
+
+                    float progress = time * 2.0;
+                    float numSquares = 8.0; 
+
+                    vec2 squareSize = vec2(1.0 / numSquares, 1.0 / numSquares);
+                    vec2 checkerCoord = floor(uv / squareSize);
+
+                    bool isWhiteSquare = mod(checkerCoord.x + checkerCoord.y, 2.0) == 0.0;
+                    vec2 localUV = fract(uv / squareSize);
+
+                    bool showEntering = false;
+                    float adjustedProgress = isWhiteSquare ? progress : progress - 1.0;
+                    adjustedProgress = clamp(adjustedProgress, 0.0, 1.0);
+
+                    if (direction == 1) {
+                        showEntering = localUV.y < adjustedProgress; // Vertical
+                    } else {
+                        showEntering = localUV.x < adjustedProgress; // Horizontal
+                    }
+
+                    vec4 color1 = texture(leavingSlideTexture, uv);
+                    vec4 color2 = texture(enteringSlideTexture, uv);
+                    outColor = mix(color1, color2, float(showEntering));
+                }
+                `;
+	}
+}