Image preview working

opengl-test-two/main.cpp

@@ -1,116 +1,116 @@
 #include <GLFW/glfw3.h>
+#include <SDL2/SDL.h>
+#include <SDL2/SDL_image.h>
 #include <stdio.h>
+#include <iostream>
 
 GLuint loadBMP_custom(const char * imagepath);
 
-int main(void)
+void EnableTransparency()
 {
+        glEnable(GL_BLEND);
+        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+}
+
+GLuint LoadTexture(char *filename,int *textw,int *texth) {
+        SDL_Surface *surface;
+        GLuint textureid;
+        int mode;
+        surface = IMG_Load(filename);
+        // Or if you don't use SDL_image you can use SDL_LoadBMP here instead:
+        // surface = SDL_LoadBMP(filename);
+
+        // could not load filename
+        if (!surface) {
+                return 0;
+        }
+
+        // work out what format to tell glTexImage2D to use...
+        if (surface->format->BytesPerPixel == 3) { // RGB 24bit
+                mode = GL_RGB;
+
+        } else if (surface->format->BytesPerPixel == 4) { // RGBA 32bit
+                mode = GL_RGBA;
+        } else {
+                SDL_FreeSurface(surface);
+                return 0;
+        }
+
+        *textw=surface->w;
+        *texth=surface->h;
+        // create one texture name
+        glGenTextures(1, &textureid);
+        // tell opengl to use the generated texture name
+        glBindTexture(GL_TEXTURE_2D, textureid);
+        // this reads from the sdl surface and puts it into an opengl texture
+        glTexImage2D(GL_TEXTURE_2D, 0, mode, surface->w, surface->h, 0, mode, GL_UNSIGNED_BYTE, surface->pixels);
+        // these affect how this texture is drawn later on...glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+        // clean up
+        SDL_FreeSurface(surface);
+        return textureid;
+
+}
+
+void DrawTexture(int x, int y, GLuint textureid,int textw,int texth) {
+        //printf("x: %d\ty: %d\tw: %d\th: %d\n", x, y, textw, texth);
+        //int textw,texth;
+        // tell opengl to use the generated texture name
+        glBindTexture(GL_TEXTURE_2D, textureid);
+        glEnable(GL_TEXTURE_2D);
+        // make a rectangle
+        glBegin(GL_QUADS);
+            glTexCoord2d(0.0,0.0); glVertex2f(-1, -1);
+            glTexCoord2d(1.0,0.0); glVertex2f(1, -1);
+            glTexCoord2d(1.0,1.0); glVertex2f(1, 1);
+            glTexCoord2d(0.0,1.0); glVertex2f(-1, 1);
+        glEnd();
+        glDisable(GL_TEXTURE_2D );
+}
+
+int main(int argc, char* args[]) {
     GLFWwindow* window;
+    GLuint myglu;
+    int textw, texth;
+
 
     /* Initialize the library */
+    /* GLFW */
     if (!glfwInit())
         return -1;
-
+    /* SDL */
+    if (SDL_Init(SDL_INIT_VIDEO) < 0)
+        printf("SDL Error");
     /* Create a windowed mode window and its OpenGL context */
     window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
-    if (!window)
-    {
+    if (!window) {
         glfwTerminate();
         return -1;
     }
-
     /* Make the window's context current */
     glfwMakeContextCurrent(window);
-
     // INIT
 
-    GLuint image = loadBMP_custom("../img/tests/stones.bmp");
-
-
-
-
+    myglu=LoadTexture("../img/tests/stones.bmp",&textw,&texth);
 
     // INIT END
-
     /* Loop until the user closes the window */
-    while (!glfwWindowShouldClose(window))
-    {
+    while (!glfwWindowShouldClose(window)) {
         /* Render here */
         glClear(GL_COLOR_BUFFER_BIT);
-
         // RENDER
-
-
-
+        DrawTexture(50,50,myglu,textw,texth);
 
 
         // RENDER END
-
         /* Swap front and back buffers */
         glfwSwapBuffers(window);
-
         /* Poll for and process events */
         glfwPollEvents();
     }
-
     glfwTerminate();
     return 0;
 }
-
-GLuint loadBMP_custom(const char * imagepath) {
-    // Data read from the header of the BMP file
-    unsigned char header[54]; // Each BMP file begins by a 54-bytes header
-    unsigned int dataPos;     // Position in the file where the actual data begins
-    unsigned int width, height;
-    unsigned int imageSize;   // = width*height*3
-    // Actual RGB data
-    unsigned char * data;
-
-    // Open the file
-    FILE * file = fopen(imagepath,"rb");
-    if (!file){printf("Image could not be opened\n"); return 0;}
-
-    if ( fread(header, 1, 54, file)!=54 ){ // If not 54 bytes read : problem
-        printf("Not a correct BMP file\n");
-        return false;
-    }
-
-    if ( header[0]!='B' || header[1]!='M' ){
-        printf("Not a correct BMP file\n");
-        return 0;
-    }
-
-    // Read ints from the byte array
-    dataPos    = *(int*)&(header[0x0A]);
-    imageSize  = *(int*)&(header[0x22]);
-    width      = *(int*)&(header[0x12]);
-    height     = *(int*)&(header[0x16]);
-
-    // Some BMP files are misformatted, guess missing information
-    if (imageSize==0)    imageSize=width*height*3; // 3 : one byte for each Red, Green and Blue component
-    if (dataPos==0)      dataPos=54; // The BMP header is done that way
-
-    // Create a buffer
-    data = new unsigned char [imageSize];
-
-    // Read the actual data from the file into the buffer
-    fread(data,1,imageSize,file);
-
-    //Everything is in memory now, the file can be closed
-    fclose(file);
-
-    // Create one OpenGL texture
-    GLuint textureID;
-    glGenTextures(1, &textureID);
-
-    // "Bind" the newly created texture : all future texture functions will modify this texture
-    glBindTexture(GL_TEXTURE_2D, textureID);
-
-    // Give the image to OpenGL
-    glTexImage2D(GL_TEXTURE_2D, 0,GL_RGB, width, height, 0, GL_BGR_EXT, GL_UNSIGNED_BYTE, data);
-
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
-
-
-}