77 lines
2.4 KiB
C++
77 lines
2.4 KiB
C++
//
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// Created by lukas on 05.02.22.
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//
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#define GL_GLEXT_PROTOTYPES
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#include <cstdio>
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#include <GL/gl.h>
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#include <GL/glext.h>
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#include "bmploader.h"
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unsigned bmploader::loadBMP(const char *imagepath) {
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// Data read from the header of the BMP file
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unsigned char header[54]; // Each BMP file begins by a 54-bytes header
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unsigned int dataPos; // Position in the file where the actual data begins
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int width, height;
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unsigned int imageSize; // = width*height*3
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// Actual RGB data
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unsigned char * data;
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// Open the file
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FILE * file = fopen(imagepath,"rb");
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if (!file){printf("Image could not be opened\n"); return 0;}
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if ( fread(header, 1, 54, file)!=54 ){ // If not 54 bytes read : problem
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printf("Not a correct BMP file\n");
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return false;
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}
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if ( header[0]!='B' || header[1]!='M' ){
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printf("Not a correct BMP file\n");
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return 0;
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}
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// Read ints from the byte array
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dataPos = *(int*)&(header[0x0A]);
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imageSize = *(int*)&(header[0x22]);
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width = *(int*)&(header[0x12]);
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height = *(int*)&(header[0x16]);
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// Some BMP files are misformatted, guess missing information
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if (imageSize==0) imageSize=width*height*3; // 3 : one byte for each Red, Green and Blue component
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if (dataPos==0) dataPos=54; // The BMP header is done that way
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// Create a buffer
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data = new unsigned char [imageSize];
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// Read the actual data from the file into the buffer
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fread(data,1,imageSize,file);
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//Everything is in memory now, the file can be closed
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fclose(file);
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glEnable(GL_TEXTURE_2D);
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// Create one OpenGL texture
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unsigned textureID;
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glGenTextures(1, &textureID);
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glActiveTexture(GL_TEXTURE0);
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// "Bind" the newly created texture : all future texture functions will modify this texture
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glBindTexture(GL_TEXTURE_2D, textureID);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
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// Give the image to OpenGL
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glTexImage2D(GL_TEXTURE_2D, 0,GL_RGB, width, height, 0, GL_BGR, GL_UNSIGNED_BYTE, data);
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// Generate mipmaps, by the way.
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glGenerateMipmap(GL_TEXTURE_2D);
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return textureID;
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}
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