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/***************************************************************************
*
* Copyright (C) 2018 Advanced Driver Information Technology Joint Venture GmbH
*
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
****************************************************************************/
#include "TextureLoader.h"
TextureLoader::TextureLoader(){
;
}
// source: http://www.opengl-tutorial.org/beginners-tutorials/tutorial-5-a-textured-cube/
bool TextureLoader::loadBMP(const char * imagePath) {
// Data read from the header of the BMP file
const unsigned char headerSize = 54; // Each BMP file begins by a 54-bytes header
unsigned char header[headerSize];
GLsizei width, height;
uint16_t pixelSizeBits;
uint8_t pixelSizeBytes;
// imageSize == width*height*pixelSize, because each pixel consists of pixelSize bytes (red, green and blue)
unsigned int imageSize;
unsigned char * data;
FILE * file = fopen(imagePath,"rb");
if (!file) {
//cout << "Image file could not be opened: " << imagePath << endl;
return false;
}
if (fread(header, 1, headerSize, file) != headerSize) {
cout << "Not a correct BMP file (could not read the header): " << imagePath << endl;
fclose(file);
return false;
}
if (header[0]!='B' || header[1]!='M' ) {
cout << "Not a correct BMP file (wrong header format) :" << imagePath << endl;
fclose(file);
return false;
}
// Read fields from the BMP file header
imageSize = *(int*)(header + 0x22);
width = *(GLsizei*)(header + 0x12);
height = *(GLsizei*)(header + 0x16);
pixelSizeBits = *(uint16_t*)(header + 0x1C);
pixelSizeBytes = pixelSizeBits / 8;
if ((pixelSizeBits != 24) and (pixelSizeBits != 32)) {
cout << "unsupported pixel size of " << pixelSizeBits << " bits" << endl;
fclose(file);
return false;
}
// calculate the image size if there is no information in the header
if (imageSize==0) {
imageSize=width*height*pixelSizeBytes;
}
data = new unsigned char [imageSize];
if(fread(data,1,imageSize,file) != imageSize)
cout << "Reading error : mismatch in imageSize and amount of data read" << endl;
fclose(file);
if (pixelSizeBits == 32) {
// BMP files with an alpha channel use ABGR format for storing pixels
// OpenGLES does not have an ABGR format specifier
// therefore change pixel format from ABGR to RGBA
for (long long i = 0; i < width*height; i++) {
unsigned char a = data[i*pixelSizeBytes + 0];
unsigned char b = data[i*pixelSizeBytes + 1];
unsigned char g = data[i*pixelSizeBytes + 2];
unsigned char r = data[i*pixelSizeBytes + 3];
data[i*pixelSizeBytes] = r;
data[i*pixelSizeBytes + 1] = g;
data[i*pixelSizeBytes + 2] = b;
data[i*pixelSizeBytes + 3] = a;
}
} else if (pixelSizeBits == 24) {
for (long long i = 0; i < width*height; i++) {
unsigned char b = data[i*pixelSizeBytes];
unsigned char g = data[i*pixelSizeBytes + 1];
unsigned char r = data[i*pixelSizeBytes + 2];
data[i*pixelSizeBytes] = r;
data[i*pixelSizeBytes + 1] = g;
data[i*pixelSizeBytes + 2] = b;
}
}
bool loaded = loadArray(data, width, height, pixelSizeBits);
delete[] data;
return loaded;
}
// This function loads an array with image data
bool TextureLoader::loadArray(void * data, unsigned int width, unsigned int height, unsigned int pixelSizeBits) {
if (loaded)
// don't load the thexture if a texture was already loaded for this object
return false;
else
loaded = true;
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glGenTextures(1, &textureID);
glBindTexture(GL_TEXTURE_2D, textureID);
if (pixelSizeBits == 32) {
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
} else if (pixelSizeBits == 24) {
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
}
glGenerateMipmap(GL_TEXTURE_2D);
// set texture parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
return loaded;
}
GLuint TextureLoader::getId() {
return textureID;
}
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