From 62c2e6a1394e4ffb871d044f17c8ad3ee88fd9ed Mon Sep 17 00:00:00 2001
From: thr3343 <125277899+thr3343@users.noreply.github.com>
Date: Mon, 20 Nov 2023 12:54:40 +0000
Subject: [PATCH] Fix blocks not rendering below Y 0 (i.e. In Negative bounds )

(Hopefully won't cause performance regressions due to the Int to Float Casts + Mixed Integer + Float Workloads)
---
 .../vulkanmod/render/chunk/DrawBuffers.java   | 27 ++++++++++---------
 .../shaders/basic/terrain/terrain.vsh         |  9 ++++---
 2 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/src/main/java/net/vulkanmod/render/chunk/DrawBuffers.java b/src/main/java/net/vulkanmod/render/chunk/DrawBuffers.java
index 79351f7afa..2f61fd3e82 100644
--- a/src/main/java/net/vulkanmod/render/chunk/DrawBuffers.java
+++ b/src/main/java/net/vulkanmod/render/chunk/DrawBuffers.java
@@ -90,10 +90,9 @@ private AreaBuffer getAreaBuffer(TerrainRenderType r) {
     }
 
     private static int encodeSectionOffset(int xOffset, int yOffset, int zOffset) {
-        final int xOffset1 = (xOffset & 127)>>4;
-        final int zOffset1 = (zOffset & 127)>>4;
-        final int yOffset1 = yOffset >> 4;
-        return zOffset1 << 16 | yOffset1 << 8 | xOffset1;
+        final int xOffset1 = (xOffset & 127);
+        final int zOffset1 = (zOffset & 127);
+        return yOffset << 18 | zOffset1 << 9 | xOffset1;
     }
 
     private void updateChunkAreaOrigin(double camX, double camY, double camZ, VkCommandBuffer commandBuffer, long ptr) {
@@ -231,18 +230,22 @@ public void buildDrawBatchesDirect(TerrainRenderType terrainRenderType, double c
 
         VkCommandBuffer commandBuffer = Renderer.getCommandBuffer();
         try(MemoryStack stack = MemoryStack.stackPush()) {
-            nvkCmdBindVertexBuffers(commandBuffer, 0, 1, stack.npointer(getAreaBuffer(terrainRenderType).getId()), stack.npointer(0));
             updateChunkAreaOrigin(camX, camY, camZ, commandBuffer, stack.nmalloc(16));
-        }
 
-        if(isTranslucent) {
-            vkCmdBindIndexBuffer(commandBuffer, this.indexBuffer.getId(), 0, VK_INDEX_TYPE_UINT16);
-        }
 
-        for (var iterator = this.sectionQueues.get(terrainRenderType).iterator(isTranslucent); iterator.hasNext(); ) {
-            final DrawParameters drawParameters = iterator.next();
-            vkCmdDrawIndexed(commandBuffer, drawParameters.indexCount, drawParameters.indexCount != 0 ? 1 : 0, drawParameters.firstIndex, drawParameters.vertexOffset, drawParameters.baseInstance);
+            if (isTranslucent) {
+                vkCmdBindIndexBuffer(commandBuffer, this.indexBuffer.getId(), 0, VK_INDEX_TYPE_UINT16);
+            }
+
+            long npointer = stack.npointer(getAreaBuffer(terrainRenderType).getId());
+            long npointer1 = stack.npointer(0);
+            for (var iterator = this.sectionQueues.get(terrainRenderType).iterator(isTranslucent); iterator.hasNext(); ) {
+                final DrawParameters drawParameters = iterator.next();
+                VUtil.UNSAFE.putLong(npointer1, drawParameters.vertexOffset*20L);
+                nvkCmdBindVertexBuffers(commandBuffer, 0, 1, npointer, npointer1);
+                vkCmdDrawIndexed(commandBuffer, drawParameters.indexCount, drawParameters.indexCount != 0 ? 1 : 0, drawParameters.firstIndex, 0, drawParameters.baseInstance);
 
+            }
         }
 
 
diff --git a/src/main/resources/assets/vulkanmod/shaders/basic/terrain/terrain.vsh b/src/main/resources/assets/vulkanmod/shaders/basic/terrain/terrain.vsh
index d3e6de24ae..a205f97ae5 100644
--- a/src/main/resources/assets/vulkanmod/shaders/basic/terrain/terrain.vsh
+++ b/src/main/resources/assets/vulkanmod/shaders/basic/terrain/terrain.vsh
@@ -30,11 +30,12 @@ const vec4 UNPACK_FACTOR = vec4(127.*16.);
 const vec3 POSITION_INV = vec3(1.0 / 1900.0);
 
 void main() {
-    const vec4 baseOffset = vec4(fma(Position,POSITION_INV,ChunkOffset), 1);
-    const vec4 xyz = fma(unpackSnorm4x8(gl_InstanceIndex),UNPACK_FACTOR,baseOffset);
-    gl_Position = MVP * xyz;
+    const vec3 baseOffset = bitfieldExtract(ivec3(gl_InstanceIndex)>> ivec3(0, 18, 9), 0, 9);
+    const vec3 pos = baseOffset+fma(Position, vec3(POSITION_INV), ChunkOffset);
+    const vec4 a = vec4(pos, 1);
+    gl_Position = MVP * a;
 
-    vertexDistance = length((ModelViewMat * xyz).xyz);
+    vertexDistance = length((ModelViewMat * a).xyz);
     vertexColor = Color * sample_lightmap(Sampler2, UV2);
     texCoord0 = UV0 * UV_INV;
 //    normal = MVP * vec4(Normal, 0.0);