From a78a18a99a25ac3b9a244ed7f9a7d90c32cdd200 Mon Sep 17 00:00:00 2001
From: redstrate <git@mail.redstrate.com>
Date: Wed, 13 Oct 2021 07:25:18 -0400
Subject: [PATCH] Set scissor for imgui commands

---
 engine/gfx/vulkan/src/gfx_vulkan.cpp | 11 +++++++++++
 engine/renderer/src/imguipass.cpp    | 27 ++++++++++++++++++++-------
 2 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/engine/gfx/vulkan/src/gfx_vulkan.cpp b/engine/gfx/vulkan/src/gfx_vulkan.cpp
index f7b9be7..8f71a9c 100755
--- a/engine/gfx/vulkan/src/gfx_vulkan.cpp
+++ b/engine/gfx/vulkan/src/gfx_vulkan.cpp
@@ -1485,6 +1485,17 @@ void GFXVulkan::submit(GFXCommandBuffer* command_buffer, const platform::window_
             scissor.extent.width = command.data.set_viewport.viewport.width;
             scissor.extent.height = command.data.set_viewport.viewport.height;
 
+            vkCmdSetScissor(cmd, 0, 1, &scissor);
+        }
+            break;
+        case GFXCommandType::SetScissor:
+        {
+            VkRect2D scissor = {};
+            scissor.offset.x = command.data.set_scissor.rect.offset.x;
+            scissor.offset.y = command.data.set_scissor.rect.offset.y;
+            scissor.extent.width = command.data.set_scissor.rect.extent.width;
+            scissor.extent.height = command.data.set_scissor.rect.extent.height;
+
             vkCmdSetScissor(cmd, 0, 1, &scissor);
         }
             break;
diff --git a/engine/renderer/src/imguipass.cpp b/engine/renderer/src/imguipass.cpp
index f7e28d6..3de9a50 100755
--- a/engine/renderer/src/imguipass.cpp
+++ b/engine/renderer/src/imguipass.cpp
@@ -123,17 +123,30 @@ void ImGuiPass::render_post(GFXCommandBuffer* command_buffer, RenderTarget& targ
             if(pcmd->UserCallback != nullptr) {
                 pcmd->UserCallback(cmd_list, pcmd);
             } else {
-                ImVec4 clip_rect = {};
-                clip_rect.x = (pcmd->ClipRect.x - clip_offset.x) * clip_scale.x;
-                clip_rect.y = (pcmd->ClipRect.y - clip_offset.y) * clip_scale.y;
-                clip_rect.z = (pcmd->ClipRect.z - clip_offset.x) * clip_scale.x;
-                clip_rect.w = (pcmd->ClipRect.w - clip_offset.y) * clip_scale.y;
+                ImVec2 clip_min((pcmd->ClipRect.x - clip_offset.x) * clip_scale.x, (pcmd->ClipRect.y - clip_offset.y) * clip_scale.y);
+                ImVec2 clip_max((pcmd->ClipRect.z - clip_offset.x) * clip_scale.x, (pcmd->ClipRect.w - clip_offset.y) * clip_scale.y);
+
+                // Clamp to viewport as vkCmdSetScissor() won't accept values that are off bounds
+                if (clip_min.x < 0.0f) { clip_min.x = 0.0f; }
+                if (clip_min.y < 0.0f) { clip_min.y = 0.0f; }
+                if (clip_max.x > framebuffer_width) { clip_max.x = (float)framebuffer_width; }
+                if (clip_max.y > framebuffer_height) { clip_max.y = (float)framebuffer_height; }
+                if (clip_max.x < clip_min.x || clip_max.y < clip_min.y)
+                    continue;
+
+                // Apply scissor/clipping rectangle
+                prism::Rectangle scissor;
+                scissor.offset.x = (int32_t)(clip_min.x);
+                scissor.offset.y = (int32_t)(clip_min.y);
+                scissor.extent.width = (uint32_t)(clip_max.x - clip_min.x);
+                scissor.extent.height = (uint32_t)(clip_max.y - clip_min.y);
+
+                command_buffer->set_scissor(scissor);
 
-                if(clip_rect.x < framebuffer_width && clip_rect.y < framebuffer_height && clip_rect.z >= 0.0f && clip_rect.w >= 0.0f) {
                     command_buffer->draw_indexed(pcmd->ElemCount,
                                                 (index_offset + pcmd->IdxOffset),
                                                 (vertex_offset + pcmd->VtxOffset), 0);
-                }
+
             }
         }