1 | // WriteTGA.c |
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2 | // Captures the current screen/window from the OpenGL context |
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3 | // and writes the pixels out as a targa formatted file. |
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4 | // Richard S. Wright Jr. |
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5 | // OpenGL SuperBible |
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6 | |
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7 | #include <stdio.h> |
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8 | #include <stdlib.h> |
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9 | |
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10 | #include "../include/GL/glew.h" |
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11 | #include "../include/TGA.h" |
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12 | |
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13 | //////////////////////////////////////////////////////////////////// |
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14 | // Capture the current viewport and save it as a targa file. |
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15 | // Be sure and call SwapBuffers for double buffered contexts or |
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16 | // glFinish for single buffered contexts before calling this function. |
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17 | // Returns 0 if an error occurs, or 1 on success. |
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18 | GLint gltWriteTGA(const char *szFileName) |
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19 | { |
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20 | FILE *pFile; // File pointer |
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21 | TGAHEADER tgaHeader; // TGA file header |
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22 | unsigned long lImageSize; // Size in bytes of image |
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23 | GLbyte *pBits = NULL; // Pointer to bits |
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24 | GLint iViewport[4]; // Viewport in pixels |
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25 | GLint lastBuffer; // Storage for the current read buffer setting |
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26 | |
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27 | // Get the viewport dimensions |
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28 | glGetIntegerv(GL_VIEWPORT, iViewport); |
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29 | |
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30 | // How big is the image going to be (targas are tightly packed) |
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31 | lImageSize = iViewport[2] * 3 * iViewport[3]; |
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32 | |
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33 | // Allocate block. If this doesn't work, go home |
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34 | pBits = (GLbyte *)malloc(lImageSize); |
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35 | if(pBits == NULL) |
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36 | return 0; |
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37 | |
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38 | // Read bits from color buffer |
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39 | glPixelStorei(GL_PACK_ALIGNMENT, 1); |
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40 | glPixelStorei(GL_PACK_ROW_LENGTH, 0); |
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41 | glPixelStorei(GL_PACK_SKIP_ROWS, 0); |
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42 | glPixelStorei(GL_PACK_SKIP_PIXELS, 0); |
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43 | |
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44 | // Get the current read buffer setting and save it. Switch to |
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45 | // the front buffer and do the read operation. Finally, restore |
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46 | // the read buffer state |
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47 | glGetIntegerv(GL_READ_BUFFER, &lastBuffer); |
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48 | glReadBuffer(GL_FRONT); |
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49 | glReadPixels(0, 0, iViewport[2], iViewport[3], GL_BGR_EXT, GL_UNSIGNED_BYTE, pBits); |
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50 | glReadBuffer(lastBuffer); |
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51 | |
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52 | // Initialize the Targa header |
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53 | tgaHeader.identsize = 0; |
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54 | tgaHeader.colorMapType = 0; |
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55 | tgaHeader.imageType = 2; |
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56 | tgaHeader.colorMapStart = 0; |
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57 | tgaHeader.colorMapLength = 0; |
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58 | tgaHeader.colorMapBits = 0; |
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59 | tgaHeader.xstart = 0; |
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60 | tgaHeader.ystart = 0; |
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61 | tgaHeader.width = iViewport[2]; |
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62 | tgaHeader.height = iViewport[3]; |
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63 | tgaHeader.bits = 24; |
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64 | tgaHeader.descriptor = 0; |
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65 | |
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66 | // Do byte swap for big vs little endian |
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67 | #ifdef __APPLE__ |
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68 | BYTE_SWAP(tgaHeader.colorMapStart); |
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69 | BYTE_SWAP(tgaHeader.colorMapLength); |
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70 | BYTE_SWAP(tgaHeader.xstart); |
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71 | BYTE_SWAP(tgaHeader.ystart); |
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72 | BYTE_SWAP(tgaHeader.width); |
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73 | BYTE_SWAP(tgaHeader.height); |
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74 | #endif |
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75 | |
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76 | // Attempt to open the file |
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77 | pFile = fopen(szFileName, "wb"); |
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78 | if(pFile == NULL) |
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79 | { |
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80 | free(pBits); // Free buffer and return error |
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81 | return 0; |
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82 | } |
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83 | |
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84 | // Write the header |
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85 | fwrite(&tgaHeader, sizeof(TGAHEADER), 1, pFile); |
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86 | |
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87 | // Write the image data |
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88 | fwrite(pBits, lImageSize, 1, pFile); |
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89 | |
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90 | // Free temporary buffer and close the file |
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91 | free(pBits); |
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92 | fclose(pFile); |
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93 | |
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94 | // Success! |
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95 | return 1; |
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96 | } |
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