Convert particle shader resource override to Veil GLSL shader transfo…

…rmer

src/client/java/org/ladysnake/effective/core/Effective.java

@@ -1,5 +1,6 @@
 package org.ladysnake.effective.core;
 
+import foundry.veil.platform.VeilEventPlatform;
 import net.fabricmc.api.ClientModInitializer;
 import net.fabricmc.fabric.api.client.event.lifecycle.v1.ClientTickEvents;
 import net.fabricmc.fabric.api.client.networking.v1.ClientPlayConnectionEvents;
@@ -32,6 +33,7 @@
 import org.ladysnake.effective.core.render.entity.model.SplashModel;
 import org.ladysnake.effective.core.render.entity.model.SplashRimModel;
 import org.ladysnake.effective.core.render.particle.SoftParticleRenderType;
+import org.ladysnake.effective.core.render.transformer.EffectiveTransparencyFixPreProcessor;
 import org.ladysnake.effective.core.world.RenderedHypnotizingEntities;
 import org.ladysnake.effective.core.world.WaterfallCloudGenerators;
 import org.ladysnake.satin.api.event.EntitiesPreRenderCallback;
@@ -247,5 +249,10 @@ public void onInitializeClient() {
 				freezeFrames = -1;
 			}
 		});
+
+
+		VeilEventPlatform.INSTANCE.onVeilAddShaderProcessors((provider, registry) -> {
+			registry.addPreprocessor(new EffectiveTransparencyFixPreProcessor(), false);
+		});
 	}
 }

src/client/java/org/ladysnake/effective/core/render/transformer/EffectiveTransparencyFixPreProcessor.java

@@ -0,0 +1,65 @@
+package org.ladysnake.effective.core.render.transformer;
+
+import foundry.veil.api.client.render.shader.processor.ShaderPreProcessor;
+import foundry.veil.api.glsl.GlslSyntaxException;
+import foundry.veil.api.glsl.node.GlslNode;
+import foundry.veil.api.glsl.node.GlslNodeList;
+import foundry.veil.api.glsl.node.GlslTree;
+import foundry.veil.api.glsl.node.branch.GlslSelectionNode;
+import foundry.veil.api.glsl.node.expression.GlslCompareNode;
+import foundry.veil.api.glsl.node.primary.GlslFloatConstantNode;
+import foundry.veil.lib.anarres.cpp.LexerException;
+import net.minecraft.util.Identifier;
+
+import java.io.IOException;
+
+/**
+ * A pre-processor intended to verify the Minecraft particle transparency check isn't active.
+ * <p>
+ * Intended to transform:
+ * <pre>{@code
+ * if (color.a < 0.1) {
+ * 	discard;
+ * }
+ * }
+ *
+ * Into the following:
+ * <pre>{@code
+ * if (color.a < 0.0000001) {
+ * 	discard;
+ * }
+ *
+ * Inside of any fragment shader named <code>particle</code>.
+ */
+public class EffectiveTransparencyFixPreProcessor implements ShaderPreProcessor {
+
+	public static final float NEW_TRANSPARENCY_THRESHOLD = 0.0000001f;
+
+	@Override
+	public void modify(final Context ctx, final GlslTree tree) {
+		final Identifier name = ctx.name();
+		assert name != null;
+
+		if (!ctx.isSourceFile()) return;
+		if (!name.getNamespace().equals("minecraft") || !name.getPath().equals("shaders/core/particle.fsh")) return;
+
+		final GlslNodeList mainFunctionBody = tree.mainFunction().orElseThrow().getBody();
+		assert mainFunctionBody != null : "Main function body is null";
+
+		for (final GlslNode node : mainFunctionBody) {
+
+			if (node instanceof GlslSelectionNode selectionNode && selectionNode.getExpression() instanceof GlslCompareNode compareNode) {
+
+				// We know there's an if statement (selectionNode) with a comparison inside it
+				// If the second part of the comparison is 0.1, and the comparison type is "less than", we can assume it's the transparency check
+
+				if (compareNode.getOperand() == GlslCompareNode.Operand.LESS &&
+					compareNode.getSecond() instanceof GlslFloatConstantNode floatConstant &&
+					Math.abs(floatConstant.floatValue() - 0.1) < 0.0001) { // Arbitrary epsilon
+					compareNode.setSecond(new GlslFloatConstantNode(NEW_TRANSPARENCY_THRESHOLD));
+				}
+			}
+		}
+	}
+
+}