Fix indirect buffer barriers

We need two barriers (for draw command buffer and draw command count
buffer) after the compute shader; we were also accidentally using the
wrong buffer in the fillBarrier.

src/niagara.cpp

@@ -672,7 +672,7 @@ int main(int argc, const char** argv)
 
 			vkCmdFillBuffer(commandBuffer, dccb.buffer, 0, 4, 0);
 
-			VkBufferMemoryBarrier fillBarrier = bufferBarrier(dcb.buffer, VK_ACCESS_TRANSFER_WRITE_BIT, VK_ACCESS_SHADER_READ_BIT | VK_ACCESS_SHADER_WRITE_BIT);
+			VkBufferMemoryBarrier fillBarrier = bufferBarrier(dccb.buffer, VK_ACCESS_TRANSFER_WRITE_BIT, VK_ACCESS_SHADER_READ_BIT | VK_ACCESS_SHADER_WRITE_BIT);
 			vkCmdPipelineBarrier(commandBuffer, VK_PIPELINE_STAGE_TRANSFER_BIT, VK_PIPELINE_STAGE_COMPUTE_SHADER_BIT, 0, 0, 0, 1, &fillBarrier, 0, 0);
 
 			vkCmdBindPipeline(commandBuffer, VK_PIPELINE_BIND_POINT_COMPUTE, drawcullPipeline);
@@ -683,8 +683,13 @@ int main(int argc, const char** argv)
 			vkCmdPushConstants(commandBuffer, drawcullProgram.layout, drawcullProgram.pushConstantStages, 0, sizeof(cullData), &cullData);
 			vkCmdDispatch(commandBuffer, uint32_t((draws.size() + 31) / 32), 1, 1);
 
-			VkBufferMemoryBarrier cullBarrier = bufferBarrier(dcb.buffer, VK_ACCESS_SHADER_WRITE_BIT, VK_ACCESS_INDIRECT_COMMAND_READ_BIT);
-			vkCmdPipelineBarrier(commandBuffer, VK_PIPELINE_STAGE_COMPUTE_SHADER_BIT, VK_PIPELINE_STAGE_DRAW_INDIRECT_BIT, 0, 0, 0, 1, &cullBarrier, 0, 0);
+			VkBufferMemoryBarrier cullBarriers[] =
+			{
+				bufferBarrier(dcb.buffer, VK_ACCESS_SHADER_WRITE_BIT, VK_ACCESS_INDIRECT_COMMAND_READ_BIT),
+				bufferBarrier(dccb.buffer, VK_ACCESS_SHADER_WRITE_BIT, VK_ACCESS_INDIRECT_COMMAND_READ_BIT),
+			};
+
+			vkCmdPipelineBarrier(commandBuffer, VK_PIPELINE_STAGE_COMPUTE_SHADER_BIT, VK_PIPELINE_STAGE_DRAW_INDIRECT_BIT, 0, 0, 0, ARRAYSIZE(cullBarriers), cullBarriers, 0, 0);
 
 			vkCmdWriteTimestamp(commandBuffer, VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT, queryPoolTimestamp, 3);
 		}