From 3661e39ac1de1fd88e095b5c7ee9bf44c71bb83f Mon Sep 17 00:00:00 2001
From: Gregory Wells <me@gregorywells.dev>
Date: Wed, 23 Jul 2025 16:36:39 -0400
Subject: [PATCH] support dynamic uniform buffers on metal

---
 .../src/commands/commands/metal_commands.m    | 27 +++++++++++++++--
 .../apis/metal/src/uniforms/metal_uniform.h   | 14 +++++++--
 .../apis/metal/src/uniforms/metal_uniform.m   | 29 ++++++++++++-------
 3 files changed, 56 insertions(+), 14 deletions(-)

diff --git a/projects/apis/metal/src/commands/commands/metal_commands.m b/projects/apis/metal/src/commands/commands/metal_commands.m
index 4fc5344..da2ea2a 100644
--- a/projects/apis/metal/src/commands/commands/metal_commands.m
+++ b/projects/apis/metal/src/commands/commands/metal_commands.m
@@ -117,8 +117,31 @@ void metalBindUniform(gnCommandBufferHandle buffer, gnUniform uniform, uint32_t
 
     [encoder useResources:uniform->uniform->usedResources count:uniform->uniform->usedResourceCount usage:MTLResourceUsageRead stages:MTLRenderStageVertex | MTLRenderStageFragment];
 
-    [encoder setVertexBuffer:uniform->uniform->argumentBuffers[mtlVertex] offset:0 atIndex:(set + 1)];
-    [encoder setFragmentBuffer:uniform->uniform->argumentBuffers[mtlFragment] offset:0 atIndex:(set + 1)];
+    int startIndex = 0;
+    for (int i = 0; i < dynamicOffsetCount; i++) {
+        int c = startIndex;
+        for (; c < MAX_METAL_BINDINGS; c++) {
+            if (uniform->uniform->isDynamic[c]) {
+                gnBufferUniformInfo updateInfo = {
+                    .binding = c,
+                    .dynamic = gnTrue,
+                    .offset = dynamicOffsets[i],
+                    .size = 0
+                };
+                mtlBufferUniformInfo info = {
+                    .baseInfo = &updateInfo,
+                    .buffer = (id<MTLBuffer>)uniform->uniform->usedResources[uniform->uniform->indexMap[c]]
+                };
+                mtlUpdateMetalBufferUniform(uniform, &info);
+
+                break;
+            }
+        }
+        startIndex = c + 1;
+    }
+
+    [encoder setVertexBytes:uniform->uniform->argumentBuffers[mtlVertex].contents length:uniform->uniform->encoders[mtlVertex].encodedLength atIndex:(set + 1)];
+    [encoder setFragmentBytes:uniform->uniform->argumentBuffers[mtlFragment].contents length:uniform->uniform->encoders[mtlFragment].encodedLength atIndex:(set + 1)];
 }
 
 void metalBindVertexBytes(gnCommandBufferHandle buffer, gnPushConstantLayout layout, void* data) {
diff --git a/projects/apis/metal/src/uniforms/metal_uniform.h b/projects/apis/metal/src/uniforms/metal_uniform.h
index 75e5884..1d0f4e9 100644
--- a/projects/apis/metal/src/uniforms/metal_uniform.h
+++ b/projects/apis/metal/src/uniforms/metal_uniform.h
@@ -8,6 +8,8 @@ typedef struct metalUniformBinding {
     gnUniformType type;
     uint32_t binding;
     void* data;
+
+    gnBool isDynamic;
 } metalUniformBinding;
 
 typedef id<MTLResource> mtlResource;
@@ -17,13 +19,21 @@ typedef struct gnPlatformUniform_t {
     gnShaderModuleStage stageUsed[MAX_METAL_BINDINGS];
     id<MTLArgumentEncoder> encoders[mtlMaxStage];
     id<MTLBuffer> argumentBuffers[mtlMaxStage];
-
-
     mtlResource usedResources[MAX_METAL_BINDINGS];
     int indexMap[MAX_METAL_BINDINGS];
     uint32_t usedResourceCount;
+
+    gnBool isDynamic[MAX_METAL_BINDINGS];
 } gnPlatformUniform;
 
 void updateMetalBufferUniform(gnUniform uniform, gnBufferUniformInfo* info);
 void updateMetalStorageUniform(gnUniform uniform, gnStorageUniformInfo* info);
 void updateMetalImageUniform(gnUniform uniform, gnImageUniformInfo* info);
+
+
+typedef struct mtlBufferUniformInfo {
+    gnBufferUniformInfo* baseInfo;
+    id<MTLBuffer> buffer;
+} mtlBufferUniformInfo;
+
+void mtlUpdateMetalBufferUniform(gnUniformHandle uniform, mtlBufferUniformInfo* info);
diff --git a/projects/apis/metal/src/uniforms/metal_uniform.m b/projects/apis/metal/src/uniforms/metal_uniform.m
index 955d54e..24c6c40 100644
--- a/projects/apis/metal/src/uniforms/metal_uniform.m
+++ b/projects/apis/metal/src/uniforms/metal_uniform.m
@@ -4,16 +4,25 @@
 #include "texture/metal_texture.h"
 #include <buffer/metal_buffer.h>
 
-void updateMetalBufferUniform(gnUniform uniform, gnBufferUniformInfo* info) {
-    if (uniform->uniform->indexMap[info->binding] == -1) {
-        uniform->uniform->indexMap[info->binding] = uniform->uniform->usedResourceCount;
+void mtlUpdateMetalBufferUniform(gnUniformHandle uniform, mtlBufferUniformInfo* info) {
+    if (uniform->uniform->indexMap[info->baseInfo->binding] == -1) {
+        uniform->uniform->indexMap[info->baseInfo->binding] = uniform->uniform->usedResourceCount;
         uniform->uniform->usedResourceCount++;
     }
-    uniform->uniform->usedResources[uniform->uniform->indexMap[info->binding]] = info->buffer->buffer->buffer;
-    if ((uniform->uniform->stageUsed[info->binding] & GN_VERTEX_SHADER_MODULE) == GN_VERTEX_SHADER_MODULE)
-        [uniform->uniform->encoders[mtlVertex] setBuffer:info->buffer->buffer->buffer offset:0 atIndex:uniform->uniform->indexMap[info->binding]];
-    if ((uniform->uniform->stageUsed[info->binding] & GN_FRAGMENT_SHADER_MODULE) == GN_FRAGMENT_SHADER_MODULE)
-        [uniform->uniform->encoders[mtlFragment] setBuffer:info->buffer->buffer->buffer offset:0 atIndex:uniform->uniform->index[info->binding]];
+    uniform->uniform->isDynamic[info->baseInfo->binding] = info->baseInfo->dynamic;
+    uniform->uniform->usedResources[uniform->uniform->indexMap[info->baseInfo->binding]] = info->buffer;
+    if ((uniform->uniform->stageUsed[info->baseInfo->binding] & GN_VERTEX_SHADER_MODULE) == GN_VERTEX_SHADER_MODULE)
+        [uniform->uniform->encoders[mtlVertex] setBuffer:info->buffer offset:info->baseInfo->offset atIndex:uniform->uniform->indexMap[info->baseInfo->binding]];
+    if ((uniform->uniform->stageUsed[info->baseInfo->binding] & GN_FRAGMENT_SHADER_MODULE) == GN_FRAGMENT_SHADER_MODULE)
+        [uniform->uniform->encoders[mtlFragment] setBuffer:info->buffer offset:info->baseInfo->offset atIndex:uniform->uniform->index[info->baseInfo->binding]];
+}
+
+void updateMetalBufferUniform(gnUniform uniform, gnBufferUniformInfo* info) {
+    mtlBufferUniformInfo mtlInfo = {
+        .baseInfo = info,
+        .buffer = info->buffer->buffer->buffer
+    };
+    mtlUpdateMetalBufferUniform(uniform, &mtlInfo);
 }
 void updateMetalStorageUniform(gnUniform uniform, gnStorageUniformInfo* info) {
     if (uniform->uniform->indexMap[info->binding] == -1) {
@@ -22,9 +31,9 @@ void updateMetalStorageUniform(gnUniform uniform, gnStorageUniformInfo* info) {
     }
     uniform->uniform->usedResources[uniform->uniform->indexMap[info->binding]] = info->buffer->buffer->buffer;
     if ((uniform->uniform->stageUsed[info->binding] & GN_VERTEX_SHADER_MODULE) == GN_VERTEX_SHADER_MODULE)
-        [uniform->uniform->encoders[mtlVertex] setBuffer:info->buffer->buffer->buffer offset:0 atIndex:uniform->uniform->indexMap[info->binding]];
+        [uniform->uniform->encoders[mtlVertex] setBuffer:info->buffer->buffer->buffer offset:info->offset atIndex:uniform->uniform->indexMap[info->binding]];
     if ((uniform->uniform->stageUsed[info->binding] & GN_FRAGMENT_SHADER_MODULE) == GN_FRAGMENT_SHADER_MODULE)
-        [uniform->uniform->encoders[mtlFragment] setBuffer:info->buffer->buffer->buffer offset:0 atIndex:uniform->uniform->index[info->binding]];
+        [uniform->uniform->encoders[mtlFragment] setBuffer:info->buffer->buffer->buffer offset:info->offset atIndex:uniform->uniform->index[info->binding]];
 }
 
 void updateMetalImageUniform(gnUniform uniform, gnImageUniformInfo* info) {