Vulkan: Viewport and Scissor offset

backends/imgui_impl_vulkan.cpp

@@ -495,28 +495,28 @@ static void ImGui_ImplVulkan_SetupRenderState(ImDrawData* draw_data, VkPipeline
     }
 
     // Setup viewport:
-    {
-        VkViewport viewport;
-        viewport.x = 0;
-        viewport.y = 0;
-        viewport.width = (float)fb_width;
-        viewport.height = (float)fb_height;
-        viewport.minDepth = 0.0f;
-        viewport.maxDepth = 1.0f;
-        vkCmdSetViewport(command_buffer, 0, 1, &viewport);
-    }
+
+    VkViewport viewport;
+    viewport.x = draw_data->OwnerViewport->Pos.x;
+    viewport.y = draw_data->OwnerViewport->Pos.y;
+    viewport.width = (float)fb_width;
+    viewport.height = (float)fb_height;
+    viewport.minDepth = 0.0f;
+    viewport.maxDepth = 1.0f;
+    vkCmdSetViewport(command_buffer, 0, 1, &viewport);
+
 
     // Setup scale and translation:
     // Our visible imgui space lies from draw_data->DisplayPps (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right). DisplayPos is (0,0) for single viewport apps.
     {
-        float scale[2];
-        scale[0] = 2.0f / draw_data->DisplaySize.x;
-        scale[1] = 2.0f / draw_data->DisplaySize.y;
-        float translate[2];
-        translate[0] = -1.0f - draw_data->DisplayPos.x * scale[0];
-        translate[1] = -1.0f - draw_data->DisplayPos.y * scale[1];
-        vkCmdPushConstants(command_buffer, bd->PipelineLayout, VK_SHADER_STAGE_VERTEX_BIT, sizeof(float) * 0, sizeof(float) * 2, scale);
-        vkCmdPushConstants(command_buffer, bd->PipelineLayout, VK_SHADER_STAGE_VERTEX_BIT, sizeof(float) * 2, sizeof(float) * 2, translate);
+        float scale_translate[4];
+        //first two are scale
+        scale_translate[0] = 2.0f / draw_data->DisplaySize.x;
+        scale_translate[1] = 2.0f / draw_data->DisplaySize.y;
+        //second two are translate
+        scale_translate[2] = -1.0f - draw_data->DisplayPos.x * scale_translate[0];
+        scale_translate[3] = -1.0f - draw_data->DisplayPos.y * scale_translate[1];
+        vkCmdPushConstants(command_buffer, bd->PipelineLayout, VK_SHADER_STAGE_VERTEX_BIT, 0, sizeof(float) * 4, scale_translate);
     }
 }
 
@@ -629,23 +629,35 @@ void ImGui_ImplVulkan_RenderDrawData(ImDrawData* draw_data, VkCommandBuffer comm
             else
             {
                 // Project scissor/clipping rectangles into framebuffer space
-                ImVec2 clip_min((pcmd->ClipRect.x - clip_off.x) * clip_scale.x, (pcmd->ClipRect.y - clip_off.y) * clip_scale.y);
-                ImVec2 clip_max((pcmd->ClipRect.z - clip_off.x) * clip_scale.x, (pcmd->ClipRect.w - clip_off.y) * clip_scale.y);
+                ImVec2 scissor_offset{
+                    pcmd->ClipRect.x * clip_scale.x, 
+                    pcmd->ClipRect.y * clip_scale.y
+                };
+                ImVec2 scissor_extent{
+                    (pcmd->ClipRect.z - clip_off.x) * clip_scale.x,
+                    (pcmd->ClipRect.w - clip_off.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 > fb_width) { clip_max.x = (float)fb_width; }
-                if (clip_max.y > fb_height) { clip_max.y = (float)fb_height; }
-                if (clip_max.x <= clip_min.x || clip_max.y <= clip_min.y)
+                if (scissor_offset.x < 0.0f) { scissor_offset.x = 0.0f; }
+                if (scissor_offset.y < 0.0f) { scissor_offset.y = 0.0f; }
+                const float scissor_rect_right = scissor_offset.x + scissor_extent.x;
+                const float scissor_rect_bottom = scissor_offset.y + scissor_offset.y;
+                if (scissor_rect_right > fb_width) { scissor_extent.x = (float)fb_width - scissor_offset.x; }
+                if (scissor_rect_bottom > fb_height) { scissor_extent.y = (float)fb_height - scissor_offset.y; }
+                if(scissor_extent.x <= 0.f || scissor_extent.y <= 0.f){
+                    continue;
+                }
+                if(scissor_offset.x >= fb_width || scissor_offset.y >= fb_height){
                     continue;
+                }
 
                 // Apply scissor/clipping rectangle
                 VkRect2D 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);
+                scissor.offset.x = (int32_t)(scissor_offset.x);
+                scissor.offset.y = (int32_t)(scissor_offset.y);
+                scissor.extent.width = uint32_t(scissor_extent.x);
+                scissor.extent.height = uint32_t(scissor_extent.y);
                 vkCmdSetScissor(command_buffer, 0, 1, &scissor);
 
                 // Bind DescriptorSet with font or user texture

imgui.cpp

@@ -15816,7 +15816,6 @@ static void ImGui::UpdateViewportsNewFrame()
     // FIXME-VIEWPORT: Size is driven by backend/user code for backward-compatibility but we should aim to make this more consistent.
     ImGuiViewportP* main_viewport = g.Viewports[0];
     main_viewport->Flags = ImGuiViewportFlags_IsPlatformWindow | ImGuiViewportFlags_OwnedByApp;
-    main_viewport->Pos = ImVec2(0.0f, 0.0f);
     main_viewport->Size = g.IO.DisplaySize;
     main_viewport->FramebufferScale = g.IO.DisplayFramebufferScale;
     IM_ASSERT(main_viewport->FramebufferScale.x > 0.0f && main_viewport->FramebufferScale.y > 0.0f);