1//
2// Copyright (c) 2014 The ANGLE Project Authors. All rights reserved.
3// Use of this source code is governed by a BSD-style license that can be
4// found in the LICENSE file.
5//
6
7#include "tga_utils.h"
8
9#include <iostream>
10#include <fstream>
11#include <string>
12#include <cstdint>
13
14TGAImage::TGAImage()
15    : data(0), width(0), height(0)
16{
17}
18
19struct TGAHeader
20{
21    uint8_t idSize;
22    uint8_t mapType;
23    uint8_t imageType;
24    uint16_t paletteStart;
25    uint16_t paletteSize;
26    uint8_t paletteEntryDepth;
27    uint16_t x;
28    uint16_t y;
29    uint16_t width;
30    uint16_t height;
31    uint8_t colorDepth;
32    uint8_t descriptor;
33};
34
35#define INVERTED_BIT (1 << 5)
36
37template <typename dataType>
38void readBinary(std::ifstream &stream, dataType &item)
39{
40    stream.read(reinterpret_cast<char *>(&item), sizeof(dataType));
41}
42
43template <typename dataType>
44void readBinary(std::ifstream &stream, std::vector<dataType> &items)
45{
46    stream.read(reinterpret_cast<char *>(items.data()), sizeof(dataType) * items.size());
47}
48
49bool LoadTGAImageFromFile(const std::string &path, TGAImage *image)
50{
51    std::ifstream stream(path, std::ios::binary);
52    if (!stream)
53    {
54        std::cerr << "error opening tga file " << path << " for reading.\n";
55        return false;
56    }
57
58    TGAHeader header;
59    readBinary(stream, header.idSize);
60    readBinary(stream, header.mapType);
61    readBinary(stream, header.imageType);
62    readBinary(stream, header.paletteStart);
63    readBinary(stream, header.paletteSize);
64    readBinary(stream, header.paletteEntryDepth);
65    readBinary(stream, header.x);
66    readBinary(stream, header.y);
67    readBinary(stream, header.width);
68    readBinary(stream, header.height);
69    readBinary(stream, header.colorDepth);
70    readBinary(stream, header.descriptor);
71
72    image->width = header.width;
73    image->height = header.height;
74
75    size_t pixelComponentCount = header.colorDepth / CHAR_BIT;
76    std::vector<unsigned char> buffer(header.width * header.height * pixelComponentCount);
77    readBinary(stream, buffer);
78
79    image->data.reserve(header.width * header.height);
80
81    for (size_t y = 0; y < header.height; y++)
82    {
83        size_t rowIdx = ((header.descriptor & INVERTED_BIT) ? (header.height - 1 - y) : y) * header.width * pixelComponentCount;
84        for (size_t x = 0; x < header.width; x++)
85        {
86            size_t pixelIdx = rowIdx + x * pixelComponentCount;
87
88            Byte4 pixel;
89            pixel[0] = (pixelComponentCount > 2) ? buffer[pixelIdx + 2] : 0;
90            pixel[2] = (pixelComponentCount > 0) ? buffer[pixelIdx + 0] : 0;
91            pixel[1] = (pixelComponentCount > 1) ? buffer[pixelIdx + 1] : 0;
92            pixel[3] = (pixelComponentCount > 3) ? buffer[pixelIdx + 3] : 255;
93
94            image->data.push_back(pixel);
95        }
96    }
97
98    std::cout << "loaded image " << path << ".\n";
99
100    return true;
101}
102
103GLuint LoadTextureFromTGAImage(const TGAImage &image)
104{
105    if (image.width > 0 && image.height > 0)
106    {
107        GLuint texture;
108        glGenTextures(1, &texture);
109        glBindTexture(GL_TEXTURE_2D, texture);
110        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
111        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
112        glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
113        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, static_cast<GLsizei>(image.width), static_cast<GLsizei>(image.height), 0,
114                     GL_RGBA, GL_UNSIGNED_BYTE, image.data.data());
115        glGenerateMipmap(GL_TEXTURE_2D);
116        return texture;
117    }
118    else
119    {
120        return 0;
121    }
122}
123