C语言和OpenGL实现的24位色BMP解码器

 1 #define _CRT_SECURE_NO_WARNINGS
 2 
 3 #include <stdio.h>
 4 #include <Windows.h>
 5 #include <gl/freeglut.h>
 6 
 7 float colorR[2048][2048] = { 0 };
 8 float colorG[2048][2048] = { 0 };
 9 float colorB[2048][2048] = { 0 };
10 unsigned int width = 0;
11 unsigned int height = 0;
12 
13 //从data的index开始，把前面count个字节(char)转化成int
14 unsigned int transByteToInt(char* data, int index, int count)
15 {
16     int res = data[index] & 0xff;
17     for (int i = 1; i < count; i++) {
18         res <<= 8;
19         res |= data[index - i] & 0xff;
20     }
21     return res;
22 }
23 
24 void readBmp()
25 {
26     FILE* bmpFile = fopen("F:/test.bmp", "rb");
27     char bmpHeader[14];
28     char infoHeader[40];
29     fread(bmpHeader, 1, 14, bmpFile);
30     fread(infoHeader, 1, 40, bmpFile);
31     width = transByteToInt(infoHeader, 7, 4);
32     height = transByteToInt(infoHeader, 11, 4);
33     int bitCount = transByteToInt(infoHeader, 15, 2);
34     int sizeImage = transByteToInt(infoHeader, 23, 4);
35     char color[3] = { 0 };
36     for (int h = height - 1; h >= 0; --h) {
37         for (int w = 0; w < width; ++w) {
38             fread(color, 1, 3, bmpFile);
39             colorR[h][w] = (color[2] & 0xff) / 255.0f;
40             colorG[h][w] = (color[1] & 0xff) / 255.0f;
41             colorB[h][w] = (color[0] & 0xff) / 255.0f;
42         }
43     }
44     fclose(bmpFile);
45 }
46 
47 void glInit()
48 {
49     glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
50     glMatrixMode(GL_PROJECTION);
51     glLoadIdentity();
52     glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
53 }
54 
55 void display()
56 {
57     glClear(GL_COLOR_BUFFER_BIT);
58     glBegin(GL_POINTS);
59         for (int i = 0; i < width; ++i) {
60             for (int j = 0; j < height; ++j) {
61                 glColor3f(colorR[height - j][i], colorG[height - j][i], colorB[height - j][i]);
62                 glVertex3f((float)i / width, (float)j / height, 0.0f);
63             }
64         }
65     glEnd();
66     glFlush();
67 }
68 
69 int main(int argc, char* argv[])
70 {
71     readBmp();
72     glutInit(&argc, argv);
73     glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
74     glutInitWindowPosition(0, 0);
75     glutInitWindowSize(width, height);
76     glutCreateWindow("bmp - Anti-Magic");
77     glInit();
78     glutDisplayFunc(display);
79     glutMainLoop();
80     return 0;
81 }