Emulate MDI if not present for Sodium

Author: whitebelyash

src/main/java/git/artdeell/artvk/Vk11Device.java

@@ -47,6 +47,7 @@ public class Vk11Device implements GpuDeviceBackend {
 	private final Map<ShaderCompilationKey, Vk11IntermediaryShaderModule> shaderCache = new HashMap<>();
 	private final Vk11Instance instance;
 	private final VkDevice vkDevice;
+	private final Vk11Features realFeatures;
     private final IntVMA vmaObj;
 	private final long vma;
 	private final Vk11GlslCompiler glslCompiler = new Vk11GlslCompiler();
@@ -61,16 +62,16 @@ public class Vk11Device implements GpuDeviceBackend {
     private final Vk11FramebufferCache framebufferCache;
 
 	public Vk11Device(
-		final ShaderSource defaultShaderSource,
-		final Vk11Instance instance,
-		final Vk11PhysicalDevice physicalDevice,
-		final Set<String> enabledDeviceExtensions,
-		final VkDevice vkDevice,
-		final IntVMA vma
+            final ShaderSource defaultShaderSource,
+            final Vk11Instance instance,
+            final Vk11PhysicalDevice physicalDevice,
+            final Set<String> enabledDeviceExtensions,
+            final VkDevice vkDevice,
+            final IntVMA vma
 	) {
 		this.defaultShaderSource = defaultShaderSource;
 		this.instance = instance;
-		this.vkDevice = vkDevice;
+        this.vkDevice = vkDevice;
 		this.vmaObj = vma;
         this.vma = vmaObj.ptr;
 		Set<String> extensionNames = new HashSet<>();
@@ -91,7 +92,9 @@ public Vk11Device(
         hasAnisotropy = features.samplerAnisotropy();
         hasAttributeDivisor = enabledDeviceExtensions.contains("VK_EXT_vertex_attribute_divisor");
 
-        if(!hasFillModeNonSolid) ArtVK.LOGGER.warn("Device does not support fillModeNonSolid, wireframe rendering won't work");
+		this.realFeatures = new Vk11Features(features.multiDrawIndirect());
+
+		if(!hasFillModeNonSolid) ArtVK.LOGGER.warn("Device does not support fillModeNonSolid, wireframe rendering won't work");
 
 		this.deviceInfo = new DeviceInfo(
 			physicalDevice.deviceName(),
@@ -108,7 +111,7 @@ public Vk11Device(
 				Integer.MAX_VALUE,
 				limits.maxColorAttachments()
 			),
-			new DeviceFeatures(true, enabledDeviceExtensions.contains("VK_EXT_multi_draw"), false, features.multiDrawIndirect(), true, true, true),
+			new DeviceFeatures(true, enabledDeviceExtensions.contains("VK_EXT_multi_draw"), false, true, true, true, true),
 			Collections.unmodifiableSet(extensionNames),
 			new HintsAndWorkarounds(false, false),
 			physicalDevice.deviceType()
@@ -166,6 +169,9 @@ public Vk11Instance instance() {
 	public VkDevice vkDevice() {
 		return this.vkDevice;
 	}
+	public Vk11Features realFeatures(){
+		return this.realFeatures;
+	}
 
 	public Vk11Queue graphicsQueue() {
 		return this.graphicsQueue;

src/main/java/git/artdeell/artvk/Vk11Features.java

@@ -0,0 +1,6 @@
+package git.artdeell.artvk;
+
+// Yes, it sucks, but we can't store emulated features inside real DeviceFeatures
+public record Vk11Features(
+        boolean multiDrawIndirect
+) {}

src/main/java/git/artdeell/artvk/Vk11RenderPass.java

@@ -9,6 +9,7 @@
 import com.mojang.blaze3d.systems.GpuQueryPool;
 import com.mojang.blaze3d.systems.RenderPass;
 import com.mojang.blaze3d.systems.RenderPassBackend;
+import com.mojang.blaze3d.systems.RenderSystem;
 import com.mojang.blaze3d.textures.GpuSampler;
 import com.mojang.blaze3d.textures.GpuTextureView;
 import java.nio.IntBuffer;
@@ -229,9 +230,19 @@ public void multiDrawIndexed(final @NotNull PointerBuffer firstIndexOffsets, fin
 	public void drawIndexedIndirect(final @NotNull GpuBufferSlice commands, final int drawCount) {
 		if (pipeline != null && pipeline.isValid()) {
             pushDescriptors();
-			VK10.vkCmdDrawIndexedIndirect(
-				commandBuffer(), ((Vk11GpuBuffer)commands.buffer()).vkBuffer(), commands.offset(), drawCount, VkDrawIndexedIndirectCommand.SIZEOF
-			);
+			long buf = ((Vk11GpuBuffer)commands.buffer()).vkBuffer();
+			if(device.realFeatures().multiDrawIndirect())
+				VK10.vkCmdDrawIndexedIndirect(
+					commandBuffer(), buf, commands.offset(), drawCount, VkDrawIndexedIndirectCommand.SIZEOF
+				);
+			else {
+				// Uh oh! Looping through the draws...
+				long offset = commands.offset();
+				int stride = VkDrawIndexedIndirectCommand.SIZEOF;
+				for(int i = 0; i < drawCount; i++){
+					VK10.vkCmdDrawIndexedIndirect(commandBuffer(), buf, offset + (long) i *stride, 1, stride);
+				}
+			}
 		} else {
 			throw new IllegalStateException("Pipeline is missing or not valid");
 		}
@@ -288,7 +299,16 @@ public void multiDraw(final @NotNull IntBuffer firstVertices, final @NotNull Int
 	public void drawIndirect(final @NotNull GpuBufferSlice commands, final int drawCount) {
 		if (pipeline != null && pipeline.isValid()) {
 			pushDescriptors();
-			VK10.vkCmdDrawIndirect(commandBuffer(), ((Vk11GpuBuffer)commands.buffer()).vkBuffer(), commands.offset(), drawCount, VkDrawIndirectCommand.SIZEOF);
+			long buf = ((Vk11GpuBuffer)commands.buffer()).vkBuffer();
+			if(device.realFeatures().multiDrawIndirect())
+				VK10.vkCmdDrawIndirect(commandBuffer(), buf, commands.offset(), drawCount, VkDrawIndirectCommand.SIZEOF);
+			else {
+				long offset = commands.offset();
+				int stride = VkDrawIndirectCommand.SIZEOF;
+				for(int i = 0; i < drawCount; i++){
+					VK10.vkCmdDrawIndirect(commandBuffer(), buf, offset + (long) i *stride, 1, stride);
+				}
+			}
 		} else {
 			throw new IllegalStateException("Pipeline is missing or not valid");
 		}

src/main/java/git/artdeell/compat/sodium/DrawBackendMixin.java

@@ -21,6 +21,8 @@ private static void injectBackend(CallbackInfoReturnable<DrawBackend> cir){
         if(((GpuDeviceAccessor) device).sodium$getBackend() instanceof Vk11Device){
             if(device.getDeviceInfo().features().multiDrawDirectInterleaved())
                 cir.setReturnValue(DrawBackend.VK_MULTIDRAW);
+            // Upstream Sodium uses MDI here, but we will check for generic indirect draw
+            // MDI is emulated on the backend side
             else if(device.getDeviceInfo().features().drawIndirect())
                 cir.setReturnValue(DrawBackend.VK_INDIRECT);
             else throw new IllegalStateException("Selected Vulkan device does not support neither multidraw nor indirect draw backends. Sodium might be unsupported on this device");