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Cleanup

omar 2019-09-20 18:29:17 +02:00
parent 981c193041
commit 3a31214e72
1 changed files with 1 additions and 36 deletions
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Image-Loading-and-Displaying-Examples.md

@ -148,39 +148,4 @@ MyEngineBindTexture2D(texture);
``` ```
Once you understand this design you will understand that loading image files and turning them into displayable textures is not within the scope of Dear ImGui. This is by design and is actually a good thing, because it means your code has full control over your data types and how you display them. If you want to display an image file (e.g. PNG file) into the screen, please refer to documentation and tutorials for the graphics API you are using. Once you understand this design you will understand that loading image files and turning them into displayable textures is not within the scope of Dear ImGui. This is by design and is actually a good thing, because it means your code has full control over your data types and how you display them. If you want to display an image file (e.g. PNG file) into the screen, please refer to documentation and tutorials for the graphics API you are using.
Here's a simplified OpenGL example using stb_image.h: Finally, you may call ImGui::ShowMetricsWindow() to explore/visualize/understand how the ImDrawList are generated.
// Use stb_image.h to load a PNG from disk and turn it into raw RGBA pixel data:
#define STB_IMAGE_IMPLEMENTATION
#include <stb_image.h>
[...]
int my_image_width, my_image_height;
unsigned char* my_image_data = stbi_load("my_image.png", &my_image_width, &my_image_height, NULL, 4);
// Turn the RGBA pixel data into an OpenGL texture:
GLuint my_opengl_texture;
glGenTextures(1, &my_opengl_texture);
glBindTexture(GL_TEXTURE_2D, my_opengl_texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, image_width, image_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, image_data);
// Now that we have an OpenGL texture, assuming our imgui rendering function (imgui_impl_xxx.cpp file) takes GLuint as ImTextureID, we can display it:
ImGui::Image((void*)(intptr_t)my_opengl_texture, ImVec2(my_image_width, my_image_height));
C/C++ tip: a void* is pointer-sized storage. You may safely store any pointer or integer into it by casting your value to ImTextureID / void*, and vice-versa.
Because both end-points (user code and rendering function) are under your control, you know exactly what is stored inside the ImTextureID / void*.
Examples:
GLuint my_tex = XXX;
void* my_void_ptr;
my_void_ptr = (void*)(intptr_t)my_tex; // cast a GLuint into a void* (we don't take its address! we literally store the value inside the pointer)
my_tex = (GLuint)(intptr_t)my_void_ptr; // cast a void* into a GLuint
ID3D11ShaderResourceView* my_dx11_srv = XXX;
void* my_void_ptr;
my_void_ptr = (void*)my_dx11_srv; // cast a ID3D11ShaderResourceView* into an opaque void*
my_dx11_srv = (ID3D11ShaderResourceView*)my_void_ptr; // cast a void* into a ID3D11ShaderResourceView*
Finally, you may call ImGui::ShowMetricsWindow() to explore/visualize/understand how the ImDrawList are generated.