115 lines
3.4 KiB
C++
115 lines
3.4 KiB
C++
#include<GLEWCore/glew.h>
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#include<hgl/type/DataType.h>
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#include<fstream>
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#include<iostream>
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namespace hgl
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{
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namespace graph
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{
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namespace
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{
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#pragma pack(push,1)
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struct TGAHeader
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{
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uint8 id;
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uint8 color_map_type;
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uint8 image_type; // 1 colormap image ,2 true-color,3 grayscale
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uint16 color_map_first;
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uint16 color_map_length;
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uint8 color_map_size;
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uint16 x_origin;
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uint16 y_origin;
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uint16 width;
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uint16 height;
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uint8 bit;
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uint8 image_desc;
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};
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union TGAImageDesc
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{
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//不要把此union放到上面的struct中，否则Visual C++会将此union编译成4字节。GCC无此问题
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uint8 image_desc;
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struct
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{
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uint alpha_depth:4;
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uint reserved:1;
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uint direction:1; //0 lower-left,1 upper left
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};
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};
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#pragma pack(pop)
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}//namespace
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bool LoadTGATexture(const std::string &filename,uint &tex_id)
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{
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std::ifstream file;
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file.open(filename,std::ifstream::in|std::ifstream::binary);
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if(!file.is_open())
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{
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std::cerr<<"[ERROR] open file<"<<filename<<"> failed."<<std::endl;
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return(false);
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}
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file.seekg(0,std::ifstream::end);
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const int file_length=file.tellg();
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char *data=new char[file_length];
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file.seekg(0,std::ifstream::beg);
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file.read(data,file_length);
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file.close();
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TGAHeader *header=(TGAHeader *)data;
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uint videomemory_format;
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uint source_format;
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if(header->image_type==2)
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{
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if(header->bit==24)
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{
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videomemory_format=GL_RGB8;
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source_format=GL_BGR;
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}
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else if(header->bit==32)
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{
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videomemory_format=GL_RGBA8;
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source_format=GL_BGRA;
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}
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}
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else if(header->image_type==3&&header->bit==8)
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{
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videomemory_format=GL_R8;
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source_format=GL_RED;
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}
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else
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{
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std::cerr<<"[ERROR] Image format error,filename: "<<filename<<std::endl;
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delete[] data;
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return(false);
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}
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glCreateTextures(GL_TEXTURE_2D,1,&tex_id);
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glTextureStorage2D(tex_id,1,videomemory_format,header->width,header->height);
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glTextureSubImage2D(tex_id,0,0,0,header->width,header->height,source_format,GL_UNSIGNED_BYTE,data+sizeof(TGAHeader));
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glTextureParameteri(tex_id,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
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glTextureParameteri(tex_id,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
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glTextureParameteri(tex_id,GL_TEXTURE_WRAP_S,GL_CLAMP_TO_EDGE);
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glTextureParameteri(tex_id,GL_TEXTURE_WRAP_T,GL_CLAMP_TO_EDGE);
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std::cout<<"load image file<"<<filename<<">:<"<<header->width<<"x"<<header->height<<"> to texture ok"<<std::endl;
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delete[] data;
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return(true);
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}
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}//namespace graph
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}//namespace hgl
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