The origin of all your problems

- Expose an ivec3 flw_renderOrigin in the shader api
- Internally add flw_renderOrigin in flw_light(*)
- flw_lightFetch expects an actual world position still

common/src/backend/java/dev/engine_room/flywheel/backend/engine/uniform/FrameUniforms.java

@@ -17,7 +17,7 @@
 import net.minecraft.world.phys.Vec3;
 
 public final class FrameUniforms extends UniformWriter {
-	private static final int SIZE = 96 + 64 * 9 + 16 * 4 + 8 * 2 + 8 + 4 * 10;
+	private static final int SIZE = 96 + 64 * 9 + 16 * 5 + 8 * 2 + 8 + 4 * 10;
 	static final UniformBuffer BUFFER = new UniformBuffer(Uniforms.FRAME_INDEX, SIZE);
 
 	private static final Matrix4f VIEW = new Matrix4f();
@@ -94,6 +94,8 @@ public static void update(RenderContext context) {
 
 		ptr = writeMatrices(ptr);
 
+		ptr = writeRenderOrigin(ptr, renderOrigin);
+
 		ptr = writeCamera(ptr);
 
 		var window = Minecraft.getInstance()
@@ -114,6 +116,11 @@ public static void update(RenderContext context) {
 		BUFFER.markDirty();
 	}
 
+	private static long writeRenderOrigin(long ptr, Vec3i renderOrigin) {
+		ptr = writeIVec3(ptr, renderOrigin.getX(), renderOrigin.getY(), renderOrigin.getZ());
+		return ptr;
+	}
+
 	private static void setPrev() {
 		VIEW_PREV.set(VIEW);
 		PROJECTION_PREV.set(PROJECTION);

common/src/backend/java/dev/engine_room/flywheel/backend/engine/uniform/UniformWriter.java

@@ -45,6 +45,28 @@ static long writeVec4(long ptr, float x, float y, float z, float w) {
 		return ptr + 16;
 	}
 
+	static long writeIVec2(long ptr, int x, int y) {
+		MemoryUtil.memPutInt(ptr, x);
+		MemoryUtil.memPutInt(ptr + 4, y);
+		return ptr + 8;
+	}
+
+	static long writeIVec3(long ptr, int x, int y, int z) {
+		MemoryUtil.memPutInt(ptr, x);
+		MemoryUtil.memPutInt(ptr + 4, y);
+		MemoryUtil.memPutInt(ptr + 8, z);
+		MemoryUtil.memPutInt(ptr + 12, 0); // empty component of vec4 because we don't trust std140
+		return ptr + 16;
+	}
+
+	static long writeIVec4(long ptr, int x, int y, int z, int w) {
+		MemoryUtil.memPutInt(ptr, x);
+		MemoryUtil.memPutInt(ptr + 4, y);
+		MemoryUtil.memPutInt(ptr + 8, z);
+		MemoryUtil.memPutInt(ptr + 12, w);
+		return ptr + 16;
+	}
+
 	static long writeMat4(long ptr, Matrix4f mat) {
 		ExtraMemoryOps.putMatrix4f(ptr, mat);
 		return ptr + 64;

common/src/backend/resources/assets/flywheel/flywheel/internal/api_impl.glsl

@@ -1,10 +1,10 @@
 // TODO: Add config for light smoothness. Should work at a compile flag level
 
-/// Get the light at the given world position from the given normal.
+/// Get the light at the given world position relative to flw_renderOrigin from the given normal.
 /// This may be interpolated for smooth lighting.
 bool flw_light(vec3 worldPos, vec3 normal, out vec2 light);
 
-/// Get the light at the given world position.
+/// Get the light at the given world position relative to flw_renderOrigin.
 /// This may be interpolated for smooth lighting.
 bool flw_light(vec3 worldPos, out vec2 light);
 

common/src/backend/resources/assets/flywheel/flywheel/internal/light_lut.glsl

@@ -82,7 +82,7 @@ bool flw_light(vec3 worldPos, out vec2 lightCoord) {
     // Always use the section of the block we are contained in to ensure accuracy.
     // We don't want to interpolate between sections, but also we might not be able
     // to rely on the existence neighboring sections, so don't do any extra rounding here.
-    ivec3 blockPos = ivec3(floor(worldPos));
+    ivec3 blockPos = ivec3(floor(worldPos)) + flw_renderOrigin;
 
     uint lightSectionIndex;
     if (_flw_chunkCoordToSectionIndex(blockPos >> 4, lightSectionIndex)) {
@@ -182,7 +182,7 @@ bool flw_light(vec3 worldPos, vec3 normal, out vec2 lightCoord) {
     // Always use the section of the block we are contained in to ensure accuracy.
     // We don't want to interpolate between sections, but also we might not be able
     // to rely on the existence neighboring sections, so don't do any extra rounding here.
-    ivec3 blockPos = ivec3(floor(worldPos));
+    ivec3 blockPos = ivec3(floor(worldPos)) + flw_renderOrigin;
 
     uint lightSectionIndex;
     if (_flw_chunkCoordToSectionIndex(blockPos >> 4, lightSectionIndex)) {

common/src/backend/resources/assets/flywheel/flywheel/internal/uniforms/frame.glsl

@@ -22,6 +22,8 @@ layout(std140) uniform _FlwFrameUniforms {
     mat4 flw_viewProjectionInverse;
     mat4 flw_viewProjectionPrev;
 
+    ivec4 _flw_renderOrigin;
+
     vec4 _flw_cameraPos;
     vec4 _flw_cameraPosPrev;
     vec4 _flw_cameraLook;
@@ -47,10 +49,11 @@ layout(std140) uniform _FlwFrameUniforms {
     uint _flw_debugMode;
 };
 
-#define flw_cameraPos _flw_cameraPos.xyz
-#define flw_cameraLook _flw_cameraLook.xyz
-#define flw_cameraPosPrev _flw_cameraPosPrev.xyz
-#define flw_cameraLookPrev _flw_cameraLookPrev.xyz
+#define flw_renderOrigin (_flw_renderOrigin.xyz)
+#define flw_cameraPos (_flw_cameraPos.xyz)
+#define flw_cameraLook (_flw_cameraLook.xyz)
+#define flw_cameraPosPrev (_flw_cameraPosPrev.xyz)
+#define flw_cameraLookPrev (_flw_cameraLookPrev.xyz)
 
 #define FLW_CAMERA_IN_FLUID_WATER 1
 #define FLW_CAMERA_IN_FLUID_LAVA 2

common/src/lib/resources/assets/flywheel/flywheel/light/flat.glsl

@@ -1,6 +1,6 @@
 void flw_shaderLight() {
     vec2 embeddedLight;
-    if (flw_lightFetch(ivec3(floor(flw_vertexPos.xyz)), embeddedLight)) {
+    if (flw_lightFetch(ivec3(floor(flw_vertexPos.xyz)) + flw_renderOrigin, embeddedLight)) {
         flw_fragLight = max(flw_fragLight, embeddedLight);
     }
 }