diff --git a/Image-Loading-and-Displaying-Examples.md b/Image-Loading-and-Displaying-Examples.md index 352b9fb..818bc71 100644 --- a/Image-Loading-and-Displaying-Examples.md +++ b/Image-Loading-and-Displaying-Examples.md @@ -883,7 +883,14 @@ See e.g. http://wiki.polycount.com/wiki/Texture_Coordinates For the purpose of this section we use "Texture Coordinates" and "UV Coordinates" interchangeably. -The `ImGui::Image()` and `ImDrawList::AddImage()` functions allow you to pass "UV coordinates" corresponding to the upper-left and bottom-right portion of the texture you want to display. Using the default values, respectively `(0.0f, 0.0f)` and `(1.0f, 1.0f)` for those coordinates allow you to display the entire underlying texture. UV coordinates are traditionally normalized coordinates, meaning that for each axis, instead of counting a number of texels, we address a location in the texture using a number from 0.0f to 1.0f. So (0.0f, 0.0f) is generally addressing the upper-left section of the texture and (1.0f, 1.0f) is addressing the lower-right corner of the texture. +The `ImGui::Image()` and `ImDrawList::AddImage()` functions allow you to pass "UV coordinates" corresponding to the upper-left and bottom-right portion of the texture you want to display. Using the default values, respectively `(0.0f, 0.0f)` and `(1.0f, 1.0f)` for those coordinates allow you to display the entire underlying texture. UV coordinates are traditionally normalized coordinates, meaning that for each axis, instead of counting a number of texels, we address a location in the texture using a number from 0.0f to 1.0f. So (0.0f, 0.0f) is generally addressing the upper-left section of the texture and (1.0f, 1.0f) is addressing the lower-right corner of the texture. Some graphics systems may use coordinates that are inverted on the Y axis. + +```cpp +ImGui::Image((void*)my_texture, ImVec2(256, 256), ImVec2(0.0f, 0.0f), ImVec2(1.0f, 1.0f)); // Default coordinates +ImGui::Text("Flip Y coordinates:"); +ImGui::Image((void*)my_texture, ImVec2(256, 256), ImVec2(0.0f, 1.0f), ImVec2(1.0f, 0.0f)); // Flip Y coordinates +``` +![image](https://github.com/ocornut/imgui/assets/8225057/532ed112-f4ed-459b-9308-a2d30f43d03c) If you want to display part of a texture, say display a 100x200 rectangle stored from pixel (10,10) to pixel (110,210) out of a 256x256 texture, you will need to calculate the normalized coordinates of those pixels: