我试图用opengl渲染几个tga文件，只使用glDrawPixels函数而不是纹理。我基本上有显示循环，并设法显示这两个文件。之后，我尝试通过声明一个全局x GlInt变量然后在每个显示循环上递增它来将x轴上的栅格位置设置为右边。事实是，这是行不通的。如果我将一个初始值放到x，例如100，该函数将工作并将图像向右翻译100个像素，但在显示循环期间递增它并不做任何事情。关于我可能做错什么的任何想法？
//Aplicatia realizeaza deschiderea si afisarea unui fisier tga
#include "glos.h"
#include <GL/gl.h>
#include <GL/glu.h>
#include <glaux.h>
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#pragma pack(1)
typedef struct
{
GLbyte identsize; // Size of ID field that follows header (0)
GLbyte colorMapType; // 0 = None, 1 = paletted
GLbyte imageType; // 0 = none, 1 = indexed, 2 = rgb, 3 = grey, +8=rle
unsigned short colorMapStart; // First colour map entry
unsigned short colorMapLength; // Number of colors
unsigned char colorMapBits; // bits per palette entry
unsigned short xstart; // image x origin
unsigned short ystart; // image y origin
unsigned short width; // width in pixels
unsigned short height; // height in pixels
GLbyte bits; // bits per pixel (8 16, 24, 32)
GLbyte descriptor; // image descriptor
} TGAHEADER;
#pragma pack(8)
void myinit(void);
void CALLBACK myReshape(GLsizei w, GLsizei h);
void CALLBACK display(void);
GLint x = 100;
////////////////////////////////////////////////////////////////////
// Allocate memory and load targa bits. Returns pointer to new buffer,
// height, and width of texture, and the OpenGL format of data.
// Call free() on buffer when finished!
// This only works on pretty vanilla targas... 8, 24, or 32 bit color
// only, no palettes, no RLE encoding.
GLbyte *gltLoadTGA(const char *szFileName, GLint *iWidth, GLint *iHeight, GLint *iComponents, GLenum *eFormat)
{
FILE *pFile; // File pointer
TGAHEADER tgaHeader; // TGA file header
unsigned long lImageSize; // Size in bytes of image
short sDepth; // Pixel depth;
GLbyte *pBits = NULL; // Pointer to bits
// Default/Failed values
*iWidth = 0;
*iHeight = 0;
*eFormat = GL_BGR_EXT;
*iComponents = GL_RGB8;
// Attempt to open the file
pFile = fopen(szFileName, "rb");
if(pFile == NULL)
return NULL;
// Read in header (binary)
fread(&tgaHeader, sizeof(TGAHEADER), 1, pFile);
// Get width, height, and depth of texture
*iWidth = tgaHeader.width;
*iHeight = tgaHeader.height;
sDepth = tgaHeader.bits / 8;
printf ("a citit fisierul %d\n",tgaHeader.height);
// Put some validity checks here. Very simply, I only understand
// or care about 8, 24, or 32 bit targa's.
// if(tgaHeader.bits != 8 && tgaHeader.bits != 24 && tgaHeader.bits != 32)
// return NULL;
// Calculate size of image buffer
lImageSize = tgaHeader.width * tgaHeader.height * sDepth;
printf ("a citit fisierul %d\n",lImageSize);
// Allocate memory and check for success
pBits = (GLbyte*)malloc(lImageSize * sizeof(GLbyte));
if(pBits == NULL)
return NULL;
// Read in the bits
// Check for read error. This should catch RLE or other
// weird formats that I don't want to recognize
if(fread(pBits, lImageSize, 1, pFile) != 1)
{
free(pBits);
return NULL;
}
// Set OpenGL format expected
switch(sDepth)
{
case 3: // Most likely case
*eFormat = GL_BGR_EXT;
*iComponents = GL_RGB8;
break;
case 4:
*eFormat = GL_BGRA_EXT;
*iComponents = GL_RGBA8;
break;
case 1:
*eFormat = GL_LUMINANCE;
*iComponents = GL_LUMINANCE8;
break;
};
// Done with File
fclose(pFile);
// Return pointer to image data
return pBits;
}
void myinit()
{
// Black background
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
}
///////////////////////////////////////////////////////////////////////
// Called to draw scene
void CALLBACK display(void)
{
GLbyte *pImage = NULL;
GLbyte *pImage2 = NULL;
GLint iWidth, iHeight, iComponents;
GLenum eFormat;
// Clear the window with current clearing color
glClear(GL_COLOR_BUFFER_BIT);
// Targa's are 1 byte aligned
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glLoadIdentity( );
pImage = gltLoadTGA("C:\\Users\\calin.oana\\Desktop\\grafica\\ACSLAB6S\\loadtga\\321104_fishes.tga", &iWidth, &iHeight, &iComponents, &eFormat);
glTranslatef(0.01, 0, 0);
//glRasterPos2f(0.0, 0.0);
// Draw the pixmap
if(pImage != NULL)
glDrawPixels(iWidth, iHeight, eFormat, GL_UNSIGNED_BYTE, pImage);
// Don't need the image data anymore
free(pImage);
pImage = gltLoadTGA("C:\\Users\\calin.oana\\Desktop\\grafica\\ACSLAB6S\\loadtga\\mata.tga", &iWidth, &iHeight, &iComponents, &eFormat);
if (pImage != NULL)
glDrawPixels(iWidth, iHeight, eFormat, GL_UNSIGNED_BYTE, pImage);
free(pImage);
glRasterPos2i(x, 0);
x++;
// Do the buffer Swap
auxSwapBuffers();
}
//////////////////////////////////////////////////////////////
// For this example, it really doesn't matter what the
// projection is since we are using glWindowPos
void CALLBACK myReshape(GLsizei w, GLsizei h)
{
// Prevent a divide by zero, when window is too short
// (you cant make a window of zero width).
if(h == 0)
h = 1;
glViewport(0, 0, w, h);
// Reset the coordinate system before modifying
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
//glTranslatef(x++, 0, 0);
// Set the clipping volume
gluOrtho2D(0.0f, (GLfloat) w, 0.0, (GLfloat) h);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
/////////////////////////////////////////////////////////////
// Main program entrypoint
int main(int argc, char* argv[])
{
auxInitDisplayMode (AUX_DOUBLE | AUX_RGB );
auxInitPosition (0, 0, 1000, 1000);
auxInitWindow("OpenGL Image Loading");
myinit();
auxReshapeFunc (myReshape);
auxMainLoop(display);
return(0);
}
编辑：我发现了什么问题，显示功能的循环没有正常发生。