Add visual tests for blendMode() across renderers

core/test/processing/visual/src/test/blendmodes/BlendModeTest.java

@@ -0,0 +1,161 @@
+package processing.visual.src.test.blendmodes;
+
+import org.junit.jupiter.api.*;
+import processing.core.*;
+import processing.visual.src.test.base.VisualTest;
+import processing.visual.src.core.ProcessingSketch;
+import processing.visual.src.core.TestConfig;
+
+@Tag("blend-modes")
+@Tag("rendering")
+@TestMethodOrder(MethodOrderer.OrderAnnotation.class)
+public class BlendModeTest extends VisualTest {
+
+    // Draws base rects with BLEND, then overlays a green rect using the given mode
+    private ProcessingSketch createBlendTest(int mode) {
+        return new ProcessingSketch() {
+            @Override
+            public void setup(PApplet p) {
+                p.background(128);
+                p.noStroke();
+            }
+
+            @Override
+            public void draw(PApplet p) {
+                // Base layer — always drawn with normal BLEND
+                p.blendMode(PApplet.BLEND);
+                p.fill(200, 60, 60);
+                p.rect(5, 5, 30, 30);
+                p.fill(60, 60, 200);
+                p.rect(15, 15, 30, 30);
+
+                p.blendMode(mode);
+                p.fill(60, 200, 60, 160);
+                p.rect(10, 10, 30, 30);
+            }
+        };
+    }
+
+    // ========== Individual Blend Modes ==========
+
+    @Test
+    @Order(1)
+    @DisplayName("blendMode(BLEND)")
+    public void testBlend() {
+        assertVisualMatch("blend-modes/blend",
+                createBlendTest(PApplet.BLEND),
+                new TestConfig(50, 50));
+    }
+
+    @Test
+    @Order(2)
+    @DisplayName("blendMode(ADD)")
+    public void testAdd() {
+        assertVisualMatch("blend-modes/add",
+                createBlendTest(PApplet.ADD),
+                new TestConfig(50, 50));
+    }
+
+    @Test
+    @Order(3)
+    @DisplayName("blendMode(SUBTRACT)")
+    public void testSubtract() {
+        assertVisualMatch("blend-modes/subtract",
+                createBlendTest(PApplet.SUBTRACT),
+                new TestConfig(50, 50));
+    }
+
+    @Test
+    @Order(4)
+    @DisplayName("blendMode(MULTIPLY)")
+    public void testMultiply() {
+        assertVisualMatch("blend-modes/multiply",
+                createBlendTest(PApplet.MULTIPLY),
+                new TestConfig(50, 50));
+    }
+
+    @Test
+    @Order(5)
+    @DisplayName("blendMode(SCREEN)")
+    public void testScreen() {
+        assertVisualMatch("blend-modes/screen",
+                createBlendTest(PApplet.SCREEN),
+                new TestConfig(50, 50));
+    }
+
+    @Test
+    @Order(6)
+    @DisplayName("blendMode(DARKEST)")
+    public void testDarkest() {
+        assertVisualMatch("blend-modes/darkest",
+                createBlendTest(PApplet.DARKEST),
+                new TestConfig(50, 50));
+    }
+
+    @Test
+    @Order(7)
+    @DisplayName("blendMode(LIGHTEST)")
+    public void testLightest() {
+        assertVisualMatch("blend-modes/lightest",
+                createBlendTest(PApplet.LIGHTEST),
+                new TestConfig(50, 50));
+    }
+
+    @Test
+    @Order(8)
+    @DisplayName("blendMode(DIFFERENCE)")
+    public void testDifference() {
+        assertVisualMatch("blend-modes/difference",
+                createBlendTest(PApplet.DIFFERENCE),
+                new TestConfig(50, 50));
+    }
+
+    @Test
+    @Order(9)
+    @DisplayName("blendMode(EXCLUSION)")
+    public void testExclusion() {
+        assertVisualMatch("blend-modes/exclusion",
+                createBlendTest(PApplet.EXCLUSION),
+                new TestConfig(50, 50));
+    }
+
+    @Test
+    @Order(10)
+    @DisplayName("blendMode(REPLACE)")
+    public void testReplace() {
+        assertVisualMatch("blend-modes/replace",
+                createBlendTest(PApplet.REPLACE),
+                new TestConfig(50, 50));
+    }
+
+    // ========== Sequential Mode Switch ==========
+
+    @Test
+    @Order(11)
+    @DisplayName("Switching blend modes mid-sketch")
+    public void testModeSwitch() {
+        assertVisualMatch("blend-modes/mode-switch", new ProcessingSketch() {
+            @Override
+            public void setup(PApplet p) {
+                p.background(128);
+                p.noStroke();
+            }
+
+            @Override
+            public void draw(PApplet p) {
+                // Each strip should only reflect its own blend mode
+                p.blendMode(PApplet.ADD);
+                p.fill(200, 60, 60, 160);
+                p.rect(5, 5, 20, 40);
+
+                p.blendMode(PApplet.MULTIPLY);
+                p.fill(60, 200, 60, 160);
+                p.rect(15, 5, 20, 40);
+
+                p.blendMode(PApplet.BLEND);
+                p.fill(60, 60, 200, 160);
+                p.rect(25, 5, 20, 40);
+            }
+        }, new TestConfig(50, 50));
+    }
+}