Fix missing colour tint on block particles (#57)

src/main/java/codechicken/lib/render/EntityDigIconFX.java

@@ -1,5 +1,7 @@
 package codechicken.lib.render;
 
+import java.util.Arrays;
+
 import net.minecraft.client.particle.EffectRenderer;
 import net.minecraft.client.particle.EntityFX;
 import net.minecraft.client.renderer.Tessellator;
@@ -11,6 +13,9 @@ import codechicken.lib.vec.Vector3;
 
 public class EntityDigIconFX extends EntityFX {
 
+    /** Tint that leaves the particle colour untouched, for materials that don't colour their texture. */
+    public static final int NO_TINT = 0xFFFFFF;
+
     public EntityDigIconFX(World world, double x, double y, double z, double dx, double dy, double dz, IIcon icon) {
         super(world, x, y, z, dx, dy, dz);
         particleIcon = icon;
@@ -19,6 +24,18 @@ public class EntityDigIconFX extends EntityFX {
         particleScale /= 2.0F;
     }
 
+    /**
+     * Multiplies the particle colour by an 0xRRGGBB tint, the equivalent of vanilla
+     * EntityDiggingFX.applyColourMultiplier. Materials that draw a greyscale texture and colour it at render time
+     * (leaves, grass tops) need this, or their particles come out flat grey.
+     */
+    public EntityDigIconFX applyColourMultiplier(int colour) {
+        particleRed *= (colour >> 16 & 255) / 255F;
+        particleGreen *= (colour >> 8 & 255) / 255F;
+        particleBlue *= (colour & 255) / 255F;
+        return this;
+    }
+
     @Override
     public int getFXLayer() {
         return 1;
@@ -90,8 +107,24 @@ public class EntityDigIconFX extends EntityFX {
                 f9);
     }
 
+    /**
+     * @deprecated the particle is never tinted, so a material that colours a greyscale texture at render time (leaves,
+     *             grass tops) breaks into grey particles. Use
+     *             {@link #addBlockHitEffects(World, Cuboid6, int, IIcon, int, EffectRenderer)}, passing
+     *             {@link #NO_TINT} for materials whose texture is already coloured.
+     */
+    @Deprecated
     public static void addBlockHitEffects(World world, Cuboid6 bounds, int side, IIcon icon,
             EffectRenderer effectRenderer) {
+        addBlockHitEffects(world, bounds, side, icon, NO_TINT, effectRenderer);
+    }
+
+    /**
+     * Spawns a hit particle on side of bounds, tinted by colour (0xRRGGBB, {@link #NO_TINT} for none). The caller
+     * resolves the tint for the side it hit, so per-face materials like grass can tint only the faces that need it.
+     */
+    public static void addBlockHitEffects(World world, Cuboid6 bounds, int side, IIcon icon, int colour,
+            EffectRenderer effectRenderer) {
         float border = 0.1F;
         Vector3 diff = bounds.max.copy().subtract(bounds.min).add(-2 * border);
         diff.x *= world.rand.nextDouble();
@@ -106,13 +139,34 @@ public class EntityDigIconFX extends EntityFX {
         if (side == 4) diff.x = bounds.min.x - border;
         if (side == 5) diff.x = bounds.max.x + border;
 
-        effectRenderer.addEffect(
-                new EntityDigIconFX(world, pos.x, pos.y, pos.z, 0, 0, 0, icon).multiplyVelocity(0.2F)
-                        .multipleParticleScaleBy(0.6F));
+        EntityDigIconFX fx = new EntityDigIconFX(world, pos.x, pos.y, pos.z, 0, 0, 0, icon);
+        effectRenderer.addEffect(fx.applyColourMultiplier(colour).multiplyVelocity(0.2F).multipleParticleScaleBy(0.6F));
     }
 
+    /**
+     * @deprecated the particles are never tinted, so a material that colours a greyscale texture at render time
+     *             (leaves, grass tops) breaks into grey particles. Use
+     *             {@link #addBlockDestroyEffects(World, Cuboid6, IIcon[], int[], EffectRenderer)}, passing
+     *             {@link #NO_TINT} for the faces whose texture is already coloured.
+     */
+    @Deprecated
     public static void addBlockDestroyEffects(World world, Cuboid6 bounds, IIcon[] icons,
             EffectRenderer effectRenderer) {
+        int[] colours = new int[icons.length];
+        Arrays.fill(colours, NO_TINT);
+        addBlockDestroyEffects(world, bounds, icons, colours, effectRenderer);
+    }
+
+    /**
+     * Spawns break particles filling bounds, each drawn from a random face. colours holds the 0xRRGGBB tint for the
+     * matching entry of icons ({@link #NO_TINT} for none) and must be the same length, so a particle is tinted by the
+     * face it was taken from.
+     */
+    public static void addBlockDestroyEffects(World world, Cuboid6 bounds, IIcon[] icons, int[] colours,
+            EffectRenderer effectRenderer) {
+        if (icons.length != colours.length)
+            throw new IllegalArgumentException("icons and colours must have the same length");
+
         Vector3 diff = bounds.max.copy().subtract(bounds.min);
         Vector3 center = bounds.min.copy().add(bounds.max).multiply(0.5);
         Vector3 density = diff.copy().multiply(4);
@@ -121,19 +175,20 @@ public class EntityDigIconFX extends EntityFX {
         density.z = Math.ceil(density.z);
 
         for (int i = 0; i < density.x; ++i) for (int j = 0; j < density.y; ++j) for (int k = 0; k < density.z; ++k) {
-            double x = bounds.min.x + (i + 0.5) * diff.x / density.x;
-            double y = bounds.min.y + (j + 0.5) * diff.y / density.y;
-            double z = bounds.min.z + (k + 0.5) * diff.z / density.z;
-            effectRenderer.addEffect(
-                    new EntityDigIconFX(
-                            world,
-                            x,
-                            y,
-                            z,
-                            x - center.x,
-                            y - center.y,
-                            z - center.z,
-                            icons[world.rand.nextInt(icons.length)]));
+            double px = bounds.min.x + (i + 0.5) * diff.x / density.x;
+            double py = bounds.min.y + (j + 0.5) * diff.y / density.y;
+            double pz = bounds.min.z + (k + 0.5) * diff.z / density.z;
+            int iconSide = world.rand.nextInt(icons.length);
+            EntityDigIconFX fx = new EntityDigIconFX(
+                    world,
+                    px,
+                    py,
+                    pz,
+                    px - center.x,
+                    py - center.y,
+                    pz - center.z,
+                    icons[iconSide]);
+            effectRenderer.addEffect(fx.applyColourMultiplier(colours[iconSide]));
         }
     }
 }

src/test/java/codechicken/lib/render/EntityDigIconFXTest.java

@@ -0,0 +1,20 @@
+package codechicken.lib.render;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import net.minecraft.util.IIcon;
+
+import org.junit.jupiter.api.Test;
+
+public class EntityDigIconFXTest {
+
+    @Test
+    public void rejectsMismatchedIconAndColourCountsBeforeSpawning() {
+        IllegalArgumentException exception = assertThrows(
+                IllegalArgumentException.class,
+                () -> EntityDigIconFX.addBlockDestroyEffects(null, null, new IIcon[1], new int[0], null));
+
+        assertEquals("icons and colours must have the same length", exception.getMessage());
+    }
+}