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FAQ and comments about the use of ImTextureID (#562, #561, #521, #510, #497, #475 ...)

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2016-03-24 11:00:47 +01:00
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imgui.cpp
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- FREQUENTLY ASKED QUESTIONS (FAQ), TIPS
- How can I help?
- How do I update to a newer version of ImGui?
- What is ImTextureID and how do I display an image?
- Can I have multiple widgets with the same label? Can I have widget without a label? (Yes) / A primer on the use of labels/IDs in ImGui.
- I integrated ImGui in my engine and the text or lines are blurry..
- I integrated ImGui in my engine and some elements are disappearing when I move windows around..
- I integrated ImGui in my engine and some elements are clipping or disappearing when I move windows around..
- How can I load a different font than the default?
- How can I load multiple fonts?
- How can I display and input non-latin characters such as Chinese, Japanese, Korean, Cyrillic?
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Check the "API BREAKING CHANGES" sections for a list of occasional API breaking changes. If you have a problem with a function, search for its name
in the code, there will likely be a comment about it. Please report any issue to the GitHub page!
Q: What is ImTextureID and how do I display an image?
A: ImTextureID is a void* used to pass renderer-agnostic texture references around until it hits your render function.
ImGui knows nothing about what those bits represent, it just passes them around. It is up to you to decide what you want the void* to carry!
It could be an identifier to your OpenGL texture (cast GLuint to void*), a pointer to your custom engine material (cast MyMaterial* to void*), etc.
At the end of the chain, your renderer takes this void* to cast it back into whatever it needs to select a current texture to render.
Refer to examples applications, where each renderer (in a imgui_impl_xxxx.cpp file) is treating ImTextureID as a different thing.
c++ tip: OpenGL uses integers to identify textures. You can safely store an integer into a void*, just cast it to void*, don't take it's address!
Q: Can I have multiple widgets with the same label? Can I have widget without a label? (Yes)
A: Yes. A primer on the use of labels/IDs in ImGui..
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A: In your Render function, try translating your projection matrix by (0.5f,0.5f) or (0.375f,0.375f).
Also make sure your orthographic projection matrix and io.DisplaySize matches your actual framebuffer dimension.
Q. I integrated ImGui in my engine and some elements are disappearing when I move windows around..
Most likely you are mishandling the clipping rectangles in your render function. Rectangles provided by ImGui are defined as (x1,y1,x2,y2) and NOT as (x1,y1,width,height).
Q: I integrated ImGui in my engine and some elements are clipping or disappearing when I move windows around..
A: Most likely you are mishandling the clipping rectangles in your render function. Rectangles provided by ImGui are defined as (x1,y1,x2,y2) and NOT as (x1,y1,width,height).
Q: How can I load a different font than the default? (default is an embedded version of ProggyClean.ttf, rendered at size 13)
A: Use the font atlas to load the TTF file you want: