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Tweaks

omar 2019-09-20 18:53:20 +02:00
parent 5ed8e5763c
commit 275708f90b
1 changed files with 45 additions and 32 deletions
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69
Image-Loading-and-Displaying-Examples.md

@ -27,55 +27,66 @@ Two things to watch for:
### Example for OpenGL users
We will here use [stb_image.h](https://github.com/nothings/stb/blob/master/stb_image.h) to load image from disk. Grab stb_image.h and add at the top of one of your source file:
We will here use [stb_image.h](https://github.com/nothings/stb/blob/master/stb_image.h) to load images from disk.
Add at the top of one of your source file:
```
// 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>
```
You may then include `<stb_image.h>` from multiple sources, but only `#define STB_IMAGE_IMPLEMENTATION` in one of them.
Then, let's load a file from disk:
```
int my_image_width = 0;
int my_image_height = 0;
unsigned char* my_image_data = stbi_load("MyImage01.jpg", &my_image_width, &my_image_height, NULL, 4);
IM_ASSERT(my_image_data != NULL);
```
// Simple helper function to load an image into a OpenGL texture with common settings
bool LoadTextureFromFile(const char* filename, GLuint* out_texture, int* out_width, int* out_height)
{
// Load from file
int image_width = 0;
int image_height = 0;
unsigned char* image_data = stbi_load(filename, &image_width, &image_height, NULL, 4);
if (image_data == NULL)
return false;
In the snippet of code above, we added an assert (`IM_ASSERT(my_image_data != NULL)`) to check if the image file was loaded correctly. You may also use your Debugger and confirm that `my_image_data` is not null, and that `my_image_width` `my_image_width` are correct.
Now, we'll be upload our pixels into an OpenGL texture:
```
// Create a OpenGL texture identifier
GLuint my_image_texture;
glGenTextures(1, &my_image_texture);
glBindTexture(GL_TEXTURE_2D, my_image_texture);
GLuint image_texture;
glGenTextures(1, &image_texture);
glBindTexture(GL_TEXTURE_2D, image_texture);
// Setup filtering parameters for display
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
// Setup CPU->GPU upload parameters
glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
// Upload pixels into texture
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, my_image_width, my_image_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, image_data);
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);
stbi_image_free(image_data);
*out_texture = image_texture;
*out_width = image_width;
*out_height = image_height;
return true;
}
```
Now that we have an OpenGL texture and its dimension, we can add in our main loop:
At initialization time, load our texture:
```
ImGui::Begin("Test");
int my_image_width = 0;
int my_image_height = 0;
GLuint my_image_texture = 0;
bool ret = LoadTextureFromFile("../../MyImage01.jpg", &my_image_texture, &my_image_width, &my_image_height);
IM_ASSERT(ret);
```
In the snippet of code above, we added an assert (`IM_ASSERT(ret)`) to check if the image file was loaded correctly. You may also use your Debugger and confirm that `my_image_texture` is not zeroand that `my_image_width` `my_image_width` are correct.
Now that we have an DirectX9 texture and its dimensions, we can display it in our main loop:
```
ImGui::Begin("OpenGL Texture Text");
ImGui::Text("pointer = %p", my_image_texture);
ImGui::Text("size = %d x %d", my_image_width, my_image_height);
ImGui::Image((void*)(intptr_t)my_image_texture, ImVec2(my_image_width, my_image_height));
ImGui::End();
```
![image](https://user-images.githubusercontent.com/8225057/65342485-26f9d380-dbd3-11e9-967e-b279b1ad8551.png)
![image](https://user-images.githubusercontent.com/8225057/65344387-dfc21180-dbd7-11e9-9478-627403721435.png)
----
@ -125,7 +136,7 @@ ImGui::Image((void*)my_texture, ImVec2(my_image_width, my_image_height));
ImGui::End();
```
![image](https://user-images.githubusercontent.com/8225057/65342425-0467ba80-dbd3-11e9-833f-3feb5084e1da.png)
![image](https://user-images.githubusercontent.com/8225057/65344041-dedcb000-dbd6-11e9-8a52-120673e8e85f.png)
----
@ -178,6 +189,8 @@ bool LoadTextureFromFile(const char* filename, ID3D11ShaderResourceView** out_sr
*out_width = image_width;
*out_height = image_height;
stbi_image_free(image_data);
return true;
}
```