Scissor stack fix

src/main/kotlin/ru/dbotthepony/mc/otm/client/render/RenderHelper.kt

@@ -3,13 +3,11 @@ package ru.dbotthepony.mc.otm.client.render
 import com.mojang.blaze3d.platform.GlStateManager
 import com.mojang.blaze3d.systems.RenderSystem
 import com.mojang.blaze3d.vertex.*
-import net.minecraft.client.gui.GuiGraphics
 import net.minecraft.client.renderer.GameRenderer
 import net.minecraft.client.renderer.RenderStateShard
 import net.minecraft.client.renderer.RenderStateShard.LineStateShard
 import net.minecraft.client.renderer.RenderType
 import net.minecraft.client.renderer.ShaderInstance
-import net.minecraft.client.renderer.texture.TextureAtlasSprite
 import net.minecraft.resources.ResourceLocation
 import net.minecraft.server.packs.resources.ResourceProvider
 import org.apache.logging.log4j.LogManager
@@ -294,9 +292,15 @@ fun drawLine(
 	tess.end()
 }
 
-data class ScissorRect(val x: Int, val y: Int, val width: Int, val height: Int, val lock: Boolean = false) {
+data class ScissorRect(val xStart: Int, val yStart: Int, val xEnd: Int, val yEnd: Int, val lock: Boolean = false) {
+	val width: Int
+		get() = (xEnd - xStart).coerceAtLeast(0)
+
+	val height: Int
+		get() = (yEnd - yStart).coerceAtLeast(0)
+
 	fun withinBounds(x: Int, y: Int): Boolean {
-		return (x in this.x .. this.x + width) && (y in this.y .. this.y + height)
+		return (x in this.xStart .. xEnd) && (y in this.yStart .. yEnd)
 	}
 
 	fun cross(x: Int, y: Int, width: Int, height: Int): Boolean {
@@ -306,18 +310,18 @@ data class ScissorRect(val x: Int, val y: Int, val width: Int, val height: Int,
 		}
 
 		// crossing at least one line
-		if (y in this.y .. this.y + height) {
+		if (y in this.yStart .. this.yStart + height) {
-			if (x < this.x && x + width > this.x + this.width) {
+			if (x < this.xStart && x + width > this.xEnd) {
 				return true
 			}
-		} else if (x in this.x .. this.x + width) {
+		} else if (x in this.xStart .. this.xStart + width) {
-			if (y < this.y && y + height > this.y + this.height) {
+			if (y < this.yStart && y + height > this.yEnd) {
 				return true
 			}
 		}
 
 		// final test: check if scissor rect is completely inside provided rect
-		return this.x in x .. x + width && this.y in y .. y + height
+		return this.xStart in x .. x + width && this.yStart in y .. y + height
 	}
 
 	fun crossScaled(x: Float, y: Float, width: Float, height: Float): Boolean {
@@ -329,17 +333,20 @@ data class ScissorRect(val x: Int, val y: Int, val width: Int, val height: Int,
 		val scale = minecraft.window.guiScale
 		return cross((x * scale).roundToInt(), (y * scale).roundToInt(), (width * scale).roundToInt(), (height * scale).roundToInt())
 	}
+
+	fun apply() {
+		RenderSystem.enableScissor(xStart, minecraft.window.height - yStart - height, width, height)
+	}
 }
 
 private val scissorStack = ArrayDeque<ScissorRect>()
 
-@Suppress("NAME_SHADOWING")
 @JvmOverloads
 fun pushScissorRect(x: Int, y: Int, width: Int, height: Int, lock: Boolean = false) {
-	var x = x
+	var xStart = x
-	var y = y
+	var yStart = y
-	var width = width
+	var xEnd = x + width
-	var height = height
+	var yEnd = y + height
 
 	val peek = scissorStack.lastOrNull()
 
@@ -349,34 +356,31 @@ fun pushScissorRect(x: Int, y: Int, width: Int, height: Int, lock: Boolean = fal
 			return
 		}
 
-		x = x.coerceAtLeast(peek.x)
+		xStart = xStart.coerceAtLeast(peek.xStart)
-		y = y.coerceAtLeast(peek.y)
+		yStart = yStart.coerceAtLeast(peek.yStart)
-		width = width.coerceAtMost(peek.width)
+		xEnd = xEnd.coerceAtMost(peek.xEnd)
-		height = height.coerceAtMost(peek.height)
+		yEnd = yEnd.coerceAtMost(peek.yEnd)
 
-		if (peek.x == x && peek.y == y && peek.width == width && peek.height == height) {
+		if (peek.xStart == xStart && peek.yStart == yStart && peek.xEnd == xEnd && peek.yEnd == yEnd) {
 			scissorStack.add(peek)
 			return
 		}
 	}
 
-	scissorStack.add(ScissorRect(x, y, width, height, lock))
+	val new = ScissorRect(xStart, yStart, xEnd, yEnd, lock)
-	y = minecraft.window.height - y - height
+	scissorStack.add(new)
-	RenderSystem.enableScissor(x, y, width, height)
+	new.apply()
 }
 
 fun popScissorRect() {
 	scissorStack.removeLast()
-
 	val peek = scissorStack.lastOrNull()
 
 	if (peek == null) {
 		RenderSystem.disableScissor()
-		return
+	} else {
+		peek.apply()
 	}
-
-	val y = minecraft.window.height - peek.y - peek.height
-	RenderSystem.enableScissor(peek.x, y, peek.width, peek.height)
 }
 
 val currentScissorRect get() = scissorStack.lastOrNull()