Vulkan: Viewport and Scissor offset#9327
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| 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) |
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these are acceptable values, as seen immediately below at line 645, scissor is a position and size, as opposed to a min and max.
| { | ||
| // 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_min(pcmd->ClipRect.x * clip_scale.x, pcmd->ClipRect.y * clip_scale.y); |
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this double applied the offset, and cut pixels (fragments?) from the right when they were supposed to be removed from the left.
| // 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); |
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previously, this was a wasted instruction as Pos was initialized as 0 and never changed. now, it would cause the viewport and scissor to be out of sync if left alone.
Whar's the purpose of changing that? What are you trying to achieve? This whole PR seems confusing and clumsy but I would like to understand what you are trying to do. -- ImVec2 clip_min((pcmd->ClipRect.x - clip_off.x) * clip_scale.x, (pcmd->ClipRect.y - clip_off.y) * clip_scale.y);
++ ImVec2 clip_min(pcmd->ClipRect.x * clip_scale.x, pcmd->ClipRect.y * clip_scale.y);
This transformed clip rectangle from global coordinates into framebuffer coordinates.
What's the purpose of changing this? |
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It was clumsy of me to fix the bug but leave clip_min and clip_max as they were. In my lastest commit, I combined the two into framebuffer_scissor_rect, which is more reflective of how VkScissor works. Does that clear up the previous confusion? The end goal is to have multiple contexts and viewports within 1 window. This PR is step 1 towards that goal. |
Why?
Please try to reach your goal before making intermediary PR that would be breaking existing API. Note that the multi-viewports system sets viewport->Pos as values are in global coordinates space. |
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I've merged the For the rest, I'm closing for now as presently I can't trust any of it. Considering that: coding style is off, repeated commits are clumsy, there is a lack of explanation as to what is probably a XY Problem and you stated yourself this is an intermediary change toward a bigger thing which you haven't achieved yet. Please consider reaching your target and then you can evaluate what you need and make a case for it and I would happily evaluate your idea. But any time there's a coding style mismatch or unexplained or breaking changes you are exhibiting carelessness and losing trust points. So please get back to the drawing board first. Good luck :) |
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The goal was to improve viewport and scissor customization. Currently, it's assumed the viewport will start in the top left corner, and there's no way to change that.
I made it so the
VkViewport.xandVkViewport.ycan be set viadraw_data->OwnerViewport->PosA few bugs were found, most likely because the values were always 0 and never changed. I'll leave review comments where applicable.
2026-03-27.23-25-47.mp4