Added LoadTextureFromMemory() for OpenGL example.

Image-Loading-and-Displaying-Examples.md

@@ -113,16 +113,17 @@ We will here use [stb_image.h](https://github.com/nothings/stb/blob/master/stb_i
 
 Add at the top of one of your source file:
 ```cpp
+#define _CRT_SECURE_NO_WARNINGS
 #define STB_IMAGE_IMPLEMENTATION
 #include "stb_image.h"
 
 // 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)
+bool LoadTextureFromMemory(const void* data, size_t data_size, 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);
+    unsigned char* image_data = stbi_load_from_memory((const unsigned char*)data, (int)data_size, &image_width, &image_height, NULL, 4);
     if (image_data == NULL)
         return false;
 
@@ -134,13 +135,9 @@ bool LoadTextureFromFile(const char* filename, GLuint* out_texture, int* out_wid
     // 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);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); // This is required on WebGL for non power-of-two textures
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); // Same
 
     // Upload pixels into texture
-#if defined(GL_UNPACK_ROW_LENGTH) && !defined(__EMSCRIPTEN__)
     glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
-#endif
     glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, image_width, image_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, image_data);
     stbi_image_free(image_data);
 
@@ -150,6 +147,24 @@ bool LoadTextureFromFile(const char* filename, GLuint* out_texture, int* out_wid
 
     return true;
 }
+
+// Open and read a file, then forward to LoadTextureFromMemory()
+bool LoadTextureFromFile(const char* file_name, GLuint* out_texture, int* out_width, int* out_height)
+{
+    FILE* f = fopen(file_name, "rb");
+    if (f == NULL)
+        return false;
+    fseek(f, 0, SEEK_END);
+    size_t file_size = (size_t)ftell(f);
+    if (file_size == -1)
+        return false;
+    fseek(f, 0, SEEK_SET);
+    void* file_data = IM_ALLOC(file_size);
+    fread(file_data, 1, file_size, f);
+    bool ret = LoadTextureFromMemory(file_data, file_size, out_texture, out_width, out_height);
+    IM_FREE(file_data);
+    return ret;
+}
 ```
 
 Load our texture after initializing OpenGL loader (for example after `glewInit()`):
@@ -926,7 +941,7 @@ RemoveTexture(&my_texture);
 
 If instead of loading from a file you would like to load from memory, you can call `stbi_load_from_memory()` instead of `stbi_load()`. 
 All `LoadTextureFromFile()` function could be reworked to call `LoadTextureFromMemory()` which contains most of the code.
-See our implementation of `LoadTextureFromFile()` for DX11 and DX12 examples.
+See our implementation of `LoadTextureFromFile()` for OpenGL, DX11 and DX12 examples.
 
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