From 0bb04b2f8ed00a3e577ee28ba083f978cde38381 Mon Sep 17 00:00:00 2001
From: mcrcortex <18544518+MCRcortex@users.noreply.github.com>
Date: Sun, 4 Aug 2024 19:17:56 +1000
Subject: [PATCH] Very Close

---
 .../section/MDICSectionRenderer.java          | 67 ++++++++++++-------
 .../core/rendering/section/MDICViewport.java  | 15 +++++
 .../voxy/shaders/lod/gl46/bindings.glsl       | 10 +++
 .../assets/voxy/shaders/lod/gl46/cmdgen.comp  | 11 ++-
 4 files changed, 79 insertions(+), 24 deletions(-)
 create mode 100644 src/main/java/me/cortex/voxy/client/core/rendering/section/MDICViewport.java

diff --git a/src/main/java/me/cortex/voxy/client/core/rendering/section/MDICSectionRenderer.java b/src/main/java/me/cortex/voxy/client/core/rendering/section/MDICSectionRenderer.java
index e7e60499..6336fa40 100644
--- a/src/main/java/me/cortex/voxy/client/core/rendering/section/MDICSectionRenderer.java
+++ b/src/main/java/me/cortex/voxy/client/core/rendering/section/MDICSectionRenderer.java
@@ -22,6 +22,7 @@ import org.lwjgl.system.MemoryUtil;
 import java.util.List;
 
 import static org.lwjgl.opengl.ARBIndirectParameters.GL_PARAMETER_BUFFER_ARB;
+import static org.lwjgl.opengl.ARBIndirectParameters.glMultiDrawElementsIndirectCountARB;
 import static org.lwjgl.opengl.GL11.*;
 import static org.lwjgl.opengl.GL15.GL_ELEMENT_ARRAY_BUFFER;
 import static org.lwjgl.opengl.GL15.glBindBuffer;
@@ -32,23 +33,32 @@ import static org.lwjgl.opengl.GL32.glDrawElementsInstancedBaseVertex;
 import static org.lwjgl.opengl.GL33.glBindSampler;
 import static org.lwjgl.opengl.GL40C.GL_DRAW_INDIRECT_BUFFER;
 import static org.lwjgl.opengl.GL42.glDrawElementsInstancedBaseVertexBaseInstance;
-import static org.lwjgl.opengl.GL43.GL_SHADER_STORAGE_BUFFER;
+import static org.lwjgl.opengl.GL43.*;
 import static org.lwjgl.opengl.GL45.glBindTextureUnit;
 
 //Uses MDIC to render the sections
-public class MDICSectionRenderer extends AbstractSectionRenderer<BasicViewport, BasicSectionGeometryManager> {
+public class MDICSectionRenderer extends AbstractSectionRenderer<MDICViewport, BasicSectionGeometryManager> {
     private final Shader terrainShader = Shader.make()
             .add(ShaderType.VERTEX, "voxy:lod/gl46/quads2.vert")
             .add(ShaderType.FRAGMENT, "voxy:lod/gl46/quads.frag")
             .compile();
+
+
+    private final Shader commandGen = Shader.make()
+            .add(ShaderType.COMPUTE, "voxy:lod/gl46/cmdgen.comp")
+            .compile();
+
     private final GlBuffer uniform = new GlBuffer(1024).zero();
 
+    private final GlBuffer drawCountBuffer = new GlBuffer(64).zero();
+    private final GlBuffer drawCallBuffer  = new GlBuffer(5*4*400000).zero();//400k draw calls
+
     public MDICSectionRenderer(ModelStore modelStore, int maxSectionCount, long geometryCapacity) {
         super(modelStore, new BasicSectionGeometryManager(maxSectionCount, geometryCapacity));
     }
 
 
-    private void uploadUniformBuffer(BasicViewport viewport) {
+    private void uploadUniformBuffer(MDICViewport viewport) {
         long ptr = UploadStream.INSTANCE.upload(this.uniform, 0, 1024);
 
         int sx = MathHelper.floor(viewport.cameraX)>>5;
@@ -77,16 +87,11 @@ public class MDICSectionRenderer extends AbstractSectionRenderer<BasicViewport,
         LightMapHelper.bind(5);
 
         glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, SharedIndexBuffer.INSTANCE.id());
-        //glBindBuffer(GL_DRAW_INDIRECT_BUFFER, this.glCommandBuffer.id);
-        //glBindBuffer(GL_PARAMETER_BUFFER_ARB, this.glCommandCountBuffer.id);
+        glBindBuffer(GL_DRAW_INDIRECT_BUFFER, this.drawCallBuffer.id);
+        glBindBuffer(GL_PARAMETER_BUFFER_ARB, this.drawCountBuffer.id);
 
     }
 
-    //Prep the terrain draw calls for this frame, also sets up the
-    // remaining render pipeline for this frame
-    private void prepTerrainCallsAndPrep() {
-
-    }
 
     private void renderTerrain() {
         RenderLayer.getCutoutMipped().startDrawing();
@@ -97,12 +102,9 @@ public class MDICSectionRenderer extends AbstractSectionRenderer<BasicViewport,
         glBindVertexArray(RenderService.STATIC_VAO);//Needs to be before binding
         this.bindRenderingBuffers();
 
-        glDrawElementsInstancedBaseVertexBaseInstance(GL_TRIANGLES, 1000*6, GL_UNSIGNED_SHORT, 0,1,0,0);
-
+        glMultiDrawElementsIndirectCountARB(GL_TRIANGLES, GL_UNSIGNED_SHORT, 0, 0, Math.min((int)(this.geometryManager.getSectionCount()*4.4), 400_000), 0);
 
         glEnable(GL_CULL_FACE);
-
-
         glBindVertexArray(0);
         glBindSampler(0, 0);
         glBindTextureUnit(0, 0);
@@ -110,27 +112,45 @@ public class MDICSectionRenderer extends AbstractSectionRenderer<BasicViewport,
     }
 
     @Override
-    public void renderOpaque(BasicViewport viewport) {
+    public void renderOpaque(MDICViewport viewport) {
         if (this.geometryManager.getSectionCount() == 0) return;
+
+
+
+        //Tick the geometry manager to upload all invalidated metadata changes to the gpu before invoking the command gen shader
+        this.geometryManager.tick();
+
         this.uploadUniformBuffer(viewport);
+
+        //TODO compute the draw calls
+        {
+            this.commandGen.bind();
+            glBindBufferBase(GL_UNIFORM_BUFFER, 0, this.uniform.id);
+            glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1, this.drawCallBuffer.id);
+            glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 2, this.drawCountBuffer.id);
+            glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 3, this.geometryManager.getMetadataBufferId());
+            glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 4, viewport.visibilityBuffer.id);
+            glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 5, viewport.indirectLookupBuffer.id);
+            glBindBuffer(GL_DISPATCH_INDIRECT_BUFFER, this.drawCountBuffer.id);
+            glDispatchComputeIndirect(0);
+            glMemoryBarrier(GL_SHADER_STORAGE_BARRIER_BIT);
+        }
+
+        this.renderTerrain();
     }
 
     @Override
-    public void buildDrawCallsAndRenderTemporal(BasicViewport viewport, GlBuffer sectionRenderList) {
+    public void buildDrawCallsAndRenderTemporal(MDICViewport viewport, GlBuffer sectionRenderList) {
         //Can do a sneeky trick, since the sectionRenderList is a list to things to render, it invokes the culler
         // which only marks visible sections
 
 
 
-        //Tick the geometry manager to upload all invalidated metadata changes to the gpu
-        this.geometryManager.tick();
-
-
         this.renderTerrain();
     }
 
     @Override
-    public void renderTranslucent(BasicViewport viewport) {
+    public void renderTranslucent(MDICViewport viewport) {
 
     }
 
@@ -141,8 +161,8 @@ public class MDICSectionRenderer extends AbstractSectionRenderer<BasicViewport,
     }
 
     @Override
-    public BasicViewport createViewport() {
-        return new BasicViewport();
+    public MDICViewport createViewport() {
+        return new MDICViewport();
     }
 
     @Override
@@ -150,5 +170,6 @@ public class MDICSectionRenderer extends AbstractSectionRenderer<BasicViewport,
         super.free();
         this.uniform.free();
         this.terrainShader.free();
+        this.commandGen.free();
     }
 }
diff --git a/src/main/java/me/cortex/voxy/client/core/rendering/section/MDICViewport.java b/src/main/java/me/cortex/voxy/client/core/rendering/section/MDICViewport.java
new file mode 100644
index 00000000..48a72773
--- /dev/null
+++ b/src/main/java/me/cortex/voxy/client/core/rendering/section/MDICViewport.java
@@ -0,0 +1,15 @@
+package me.cortex.voxy.client.core.rendering.section;
+
+import me.cortex.voxy.client.core.gl.GlBuffer;
+import me.cortex.voxy.client.core.rendering.Viewport;
+
+public class MDICViewport extends Viewport<MDICViewport> {
+    public final GlBuffer visibilityBuffer = new GlBuffer(100_000*4);
+    public final GlBuffer indirectLookupBuffer = new GlBuffer(100_000*4+4);
+
+    @Override
+    protected void delete0() {
+        this.visibilityBuffer.free();
+        this.indirectLookupBuffer.free();
+    }
+}
diff --git a/src/main/resources/assets/voxy/shaders/lod/gl46/bindings.glsl b/src/main/resources/assets/voxy/shaders/lod/gl46/bindings.glsl
index d3f23a60..6a73788c 100644
--- a/src/main/resources/assets/voxy/shaders/lod/gl46/bindings.glsl
+++ b/src/main/resources/assets/voxy/shaders/lod/gl46/bindings.glsl
@@ -57,6 +57,9 @@ layout(binding = DRAW_BUFFER_BINDING, std430) writeonly restrict buffer DrawBuff
 
 #ifdef DRAW_COUNT_BUFFER_BINDING
 layout(binding = DRAW_COUNT_BUFFER_BINDING, std430) restrict buffer DrawCommandCountBuffer {
+    uint cmdGenDispatchX;
+    uint cmdGenDispatchY;
+    uint cmdGenDispatchZ;
     uint opaqueDrawCount;
     uint translucentDrawCount;
 };
@@ -68,6 +71,13 @@ layout(binding = SECTION_METADA_BUFFER_BINDING, std430) readonly restrict buffer
 };
 #endif
 
+#ifdef INDIRECT_SECTION_LOOKUP_BINDING
+layout(binding = INDIRECT_SECTION_LOOKUP_BINDING, std430) readonly restrict buffer IndirectSectionLookupBuffer {
+    uint sectionCount;
+    uint indirectLookup[];
+};
+#endif
+
 #ifndef VISIBILITY_ACCESS
 #define VISIBILITY_ACCESS readonly
 #endif
diff --git a/src/main/resources/assets/voxy/shaders/lod/gl46/cmdgen.comp b/src/main/resources/assets/voxy/shaders/lod/gl46/cmdgen.comp
index 1c58b73d..dcfdef0e 100644
--- a/src/main/resources/assets/voxy/shaders/lod/gl46/cmdgen.comp
+++ b/src/main/resources/assets/voxy/shaders/lod/gl46/cmdgen.comp
@@ -3,6 +3,12 @@
 
 layout(local_size_x = 128) in;
 
+#define DRAW_BUFFER_BINDING 1
+#define DRAW_COUNT_BUFFER_BINDING 2
+#define SECTION_METADA_BUFFER_BINDING 3
+#define VISIBILITY_BUFFER_BINDING 4
+#define INDIRECT_SECTION_LOOKUP_BINDING 5
+
 #import <voxy:lod/quad_format.glsl>
 #import <voxy:lod/gl46/bindings.glsl>
 #import <voxy:lod/section.glsl>
@@ -42,13 +48,16 @@ void main() {
     if (gl_GlobalInvocationID.x >= sectionCount) {
         return;
     }
-    SectionMeta meta = sectionData[gl_GlobalInvocationID.x];
+    uint sectionId = indirectLookup[gl_GlobalInvocationID.x];
+    SectionMeta meta = sectionData[sectionId];
     uint detail = extractDetail(meta);
     ivec3 ipos = extractPosition(meta);
 
     vec3 cornerPos = vec3(((ipos<<detail)-baseSectionPos)<<5)-cameraSubPos;
 
 
+    //Note! its not with respect to the sectionId
+    //
     //Check the occlusion data from last frame
     bool shouldRender = visibilityData[gl_GlobalInvocationID.x] == frameId - 1;