我正在尝试使用openGL渲染RGB帧。当在CPU上分配内存时，代码工作正常。但是，当我使用像素缓冲区对象的概念在GPU上分配内存时，我在渲染帧时遇到问题。
问题是，显示窗口是完全白色的。当在其他图形卡上运行相同的代码时，代码工作正常。但是当我在任何拥有nVidia显卡的系统上运行时，面对这个白屏问题。
以下是我的代码：
#include <stdio.h>
#include <stdlib.h>
#include "glew.h"
#include "glfw.h"
#include "glaux.h"
PFNGLGENBUFFERSARBPROC pglGenBuffersARB = 0; // VBO Name Generation Procedure
PFNGLBINDBUFFERARBPROC pglBindBufferARB = 0; // VBO Bind Procedure
PFNGLBUFFERDATAARBPROC pglBufferDataARB = 0; // VBO Data Loading Procedure
PFNGLBUFFERSUBDATAARBPROC pglBufferSubDataARB = 0; // VBO Sub Data Loading Procedure
PFNGLDELETEBUFFERSARBPROC pglDeleteBuffersARB = 0; // VBO Deletion Procedure
PFNGLGETBUFFERPARAMETERIVARBPROC pglGetBufferParameterivARB = 0; // return various parameters of VBO
PFNGLMAPBUFFERARBPROC pglMapBufferARB = 0; // map VBO procedure
PFNGLUNMAPBUFFERARBPROC pglUnmapBufferARB = 0; // unmap VBO procedure
#define glGenBuffersARB pglGenBuffersARB
#define glBindBufferARB pglBindBufferARB
#define glBufferDataARB pglBufferDataARB
#define glBufferSubDataARB pglBufferSubDataARB
#define glDeleteBuffersARB pglDeleteBuffersARB
#define glGetBufferParameterivARB pglGetBufferParameterivARB
#define glMapBufferARB pglMapBufferARB
#define glUnmapBufferARB pglUnmapBufferARB
int index;
int pboSupported;
int pboMode;
GLuint pixBuffObjs[2];
HDC hDC = NULL;
GLuint texture;
char *FileName;
unsigned char *guibuffer;
AUX_RGBImageRec texture1;
unsigned long long pos=0;
GLuint myPBO;
void initGL(void)
{
int maxSz;
int maxwidth = 416;
int maxheight = 240;
if( !glfwInit() )
{
exit( EXIT_FAILURE );
}
// if( !glfwOpenWindow(4096, 2118, 0,0,0,0,0,0, GLFW_WINDOW ) )
if( !glfwOpenWindow(maxwidth, maxheight, 0,0,0,0,0,0, GLFW_WINDOW ) ) //GLFW_FULLSCREEN
{
glfwTerminate();
exit( EXIT_FAILURE );
}
glfwSetWindowTitle("sample");
glGenBuffersARB = (PFNGLGENBUFFERSARBPROC)wglGetProcAddress("glGenBuffersARB");
glBindBufferARB = (PFNGLBINDBUFFERARBPROC)wglGetProcAddress("glBindBufferARB");
glBufferDataARB = (PFNGLBUFFERDATAARBPROC)wglGetProcAddress("glBufferDataARB");
glBufferSubDataARB = (PFNGLBUFFERSUBDATAARBPROC)wglGetProcAddress("glBufferSubDataARB");
glDeleteBuffersARB = (PFNGLDELETEBUFFERSARBPROC)wglGetProcAddress("glDeleteBuffersARB");
glGetBufferParameterivARB = (PFNGLGETBUFFERPARAMETERIVARBPROC)wglGetProcAddress("glGetBufferParameterivARB");
glMapBufferARB = (PFNGLMAPBUFFERARBPROC)wglGetProcAddress("glMapBufferARB");
glUnmapBufferARB = (PFNGLUNMAPBUFFERARBPROC)wglGetProcAddress("glUnmapBufferARB");
// check once again PBO extension
if(glGenBuffersARB && glBindBufferARB && glBufferDataARB && glBufferSubDataARB &&
glMapBufferARB && glUnmapBufferARB && glDeleteBuffersARB && glGetBufferParameterivARB)
{
pboSupported = 1;
pboMode = 1; // using 1 PBO
printf( "Video card supports GL_ARB_pixel_buffer_object.");
glGenBuffersARB(1, &pixBuffObjs[0]);
}
else
{
pboSupported = 0;
pboMode = 0; // without PBO
printf("Video card does NOT support GL_ARB_pixel_buffer_object.");
}
glGetIntegerv(GL_MAX_TEXTURE_SIZE,&maxSz);
glClearColor(0.0f, 0.0f, 0.0f, 0.0f); // This Will Clear The Background Color To Black
glClearDepth(1.0); // Enables Clearing Of The Depth Buffer
glDepthFunc(GL_LESS); // The Type Of Depth Test To Do
glEnable(GL_DEPTH_TEST); // Enables Depth Testing
glShadeModel(GL_SMOOTH); // Enables Smooth Color Shading
glMatrixMode(GL_PROJECTION);
//glLoadIdentity();
hDC= wglGetCurrentDC();
#if 1
{ // TSS
HWND hCurrentWindow = GetActiveWindow();
char szTitle[256]="sample";
//SetWindowText(hCurrentWindow, );
// SetWindowLongA (hCurrentWindow , GWL_STYLE, (GetWindowLongA (hCurrentWindow , GWL_STYLE) & ~(WS_CAPTION)));
SetWindowLongA (hCurrentWindow, GWL_STYLE, (WS_VISIBLE));
}
#endif
glEnable(GL_TEXTURE_2D);
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
}
int GL_Disply()
{
FILE *fptr=fopen("C:\\myRGB.rgb","rb");
fseek(fptr,pos,SEEK_SET);
fread(guibuffer,sizeof(unsigned char),sizeof(unsigned char)*416*240*3,fptr);
pos+=416*240*3;
texture1.sizeX =416;
texture1.sizeY =240;
texture1.data = guibuffer;
glDepthFunc(GL_ALWAYS);
glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
glEnable(GL_BLEND);
glDisable(GL_LIGHTING);
//glEnable(GL_TEXTURE_2D);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexEnvf(GL_TEXTURE_ENV,GL_TEXTURE_ENV_MODE,GL_MODULATE);
glBindBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB, myPBO);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, texture1.sizeX, texture1.sizeY, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
glBegin(GL_QUADS);
//glNormal3f( 0.0f, 0.0f, 0.0f);
glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, -1.0f, 0.0f);
glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, -1.0f, 0.0f);
glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, 1.0f, 0.0f);
glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, 1.0f, 0.0f);
glEnd();
glDisable(GL_BLEND);
glEnable(GL_DEPTH_TEST);
// Swap front and back rendering buffers
glfwSwapBuffers();
//glDeleteTextures(1, &texture);
fclose(fptr);
}
int main(int argc, char *argv[])
{
initGL(); // GL initialization
/*GPU memory allocation using C*/
glGenBuffersARB(1, &myPBO);
glBindBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB, myPBO);
glBufferDataARB(GL_PIXEL_UNPACK_BUFFER_ARB, 416*240*3, NULL, GL_STREAM_DRAW_ARB);
guibuffer=(unsigned char*)glMapBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB, GL_WRITE_ONLY_ARB);
for(index=0;index<200;index++)
{
printf("frame %d displayed\r",index);
GL_Disply();
}
return 0;
}
我已调试并检查glMapBufferARB是否正在返回一个地址，它返回一个有效地址，即那里没有BadPtr问题。我有3个系统，有3个不同型号的nVidia显卡，输出相同，就是白色屏幕。
然而，我也试过系统上有其他显卡的代码，代码可以工作。此外，OpenGL版本没有问题。
建议一些可以使上述代码有效的更改或其他内容。
答案 0 :(得分：1)
您的代码无效，应该生成错误。它不适用于不同的GPU。传统上，GL在映射到客户端内存时不能使用缓冲区对象。您必须取消映射PBO，因为您可以将其用作纹理图像规范的源。请注意，您不应在glTexImage调用后再次直接重新映射PBO，因为这会降低性能。理想情况下，您可以使用PBO的环形缓冲区来允许GL异步工作。
现代GL还通过GL_ARB_buffer_storage扩展提供了持久映射的功能（自4.4以来的核心，所以它真的是新的）。但是这有一个缺点，你必须手动将缓冲区更新与GL同步，而在这个用例中并没有真正获得任何东西。