我创建了4个纹理并将它们附加到FBO上，分别命名为fbo_texture0-fbo_texture3。如下截图所示，它们都已成功创建：
图1
现在，我想使用GLSL创建第5个纹理，该纹理是从之前的纹理（fbo_texture0-fbo_texture3）获取的。现在，我只想将第一个纹理复制到第五个纹理中。不幸的是，这是我得到的结果：
图2
问题是：
1. 我如何在GLSL中访问这些FBO纹理？ 2. 我如何创建第5个纹理？（或从第一个纹理复制到第五个纹理？）
以下是程序的完整代码（如果需要）：
图1
现在，我想使用GLSL创建第5个纹理，该纹理是从之前的纹理（fbo_texture0-fbo_texture3）获取的。现在，我只想将第一个纹理复制到第五个纹理中。不幸的是，这是我得到的结果：
图2
问题是：1. 我如何在GLSL中访问这些FBO纹理？ 2. 我如何创建第5个纹理？（或从第一个纹理复制到第五个纹理？）
以下是程序的完整代码（如果需要）：
#include <windows.h>
#include <GL/glew.h> // Include the GLEW header file
#include <GL/glut.h> // Include the GLUT header file
#include <iostream> // Allow us to print to the console
using namespace std;
bool* keyStates = new bool[256]; // Create an array of boolean values of length 256 (0-255)
unsigned int fbo; // The frame buffer object
unsigned int fbo_depth; // The depth buffer for the frame buffer object
unsigned int fbo_texture0; // The texture object to write our frame buffer object to
unsigned int fbo_texture1;
unsigned int fbo_texture2;
unsigned int fbo_texture3;
unsigned int fbo_texture4;
GLhandleARB shaderProgram;
GLhandleARB vertexShader;
GLhandleARB fragmentShader;
int window_width = 500; // The width of our window
int window_height = 500; // The height of our window
void initFrameBufferDepthBuffer(void) {
glGenRenderbuffers(1, &fbo_depth); // Generate one render buffer and store the ID in fbo_depth
glBindRenderbuffer(GL_RENDERBUFFER, fbo_depth); // Bind the fbo_depth render buffer
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, window_width, window_height); // Set the render buffer storage to be a depth component, with a width and height of the window
glBindRenderbuffer(GL_RENDERBUFFER, 0); // Unbind the render buffer
}
void initFrameBufferTextures(void) {
glGenTextures(1, &fbo_texture0); // Generate one ture
glBindTexture(GL_TEXTURE_2D, fbo_texture0); // Bind the ture fbo_texture
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, window_width, window_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); // Create a standard ture with the width and height of our window
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glBindTexture(GL_TEXTURE_2D, 0);
glGenTextures(1, &fbo_texture1); // Generate one ture
glBindTexture(GL_TEXTURE_2D, fbo_texture1); // Bind the ture fbo_texture
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, window_width, window_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); // Create a standard ture with the width and height of our window
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glBindTexture(GL_TEXTURE_2D, 0);
glGenTextures(1, &fbo_texture2); // Generate one ture
glBindTexture(GL_TEXTURE_2D, fbo_texture2); // Bind the ture fbo_texture
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, window_width, window_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); // Create a standard ture with the width and height of our window
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glBindTexture(GL_TEXTURE_2D, 0);
glGenTextures(1, &fbo_texture3); // Generate one ture
glBindTexture(GL_TEXTURE_2D, fbo_texture3); // Bind the ture fbo_texture
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, window_width, window_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); // Create a standard ture with the width and height of our window
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glBindTexture(GL_TEXTURE_2D, 0);
glGenTextures(1, &fbo_texture4); // Generate one ture
glBindTexture(GL_TEXTURE_2D, fbo_texture4); // Bind the ture fbo_texture
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, window_width, window_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); // Create a standard ture with the width and height of our window
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glBindTexture(GL_TEXTURE_2D, 0);
}
void printInfoLog(GLhandleARB obj)
{
int infologLength = 0;
int charsWritten = 0;
char* infoLog;
glGetObjectParameterivARB(obj, GL_OBJECT_INFO_LOG_LENGTH_ARB, &infologLength);
if (infologLength > 0)
{
infoLog = (char*)malloc(infologLength);
glGetInfoLogARB(obj, infologLength, &charsWritten, infoLog);
printf("%s\n",infoLog);
free(infoLog);
}
}
void initFrameBuffer(void) {
initFrameBufferDepthBuffer(); // Initialize our frame buffer depth buffer
initFrameBufferTextures(); // Initialize our frame buffer ture
glGenFramebuffers(1, &fbo); // Generate one frame buffer and store the ID in fbo
glBindFramebuffer(GL_FRAMEBUFFER, fbo); // Bind our frame buffer
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, fbo_texture0, 0);// Attach the ture fbo_texturen to the color buffer in our frame buffer
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, fbo_texture1, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT2, GL_TEXTURE_2D, fbo_texture2, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT3, GL_TEXTURE_2D, fbo_texture3, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT4, GL_TEXTURE_2D, fbo_texture4, 0);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, fbo_depth); // Attach the depth buffer fbo_depth to our frame buffer
GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER); // Check that status of our generated frame buffer
if (status != GL_FRAMEBUFFER_COMPLETE) // If the frame buffer does not report back as complete
{
cout << "Couldn't create frame buffer" << endl; // Output an error to the console
exit(0); // Exit the application
}
glBindFramebuffer(GL_FRAMEBUFFER, 0); // Unbind our frame buffer
}
void init(void) {
//glEnable(GL_TEXTURE_2D); // Enable turing so we can bind our frame buffer ture
glEnable(GL_DEPTH_TEST); // Enable depth testing
initFrameBuffer(); // Create our frame buffer object
}
void keyOperations (void) {
if (keyStates['a']) { // If the a key has been pressed
// Perform 'a' key operations
}
}
void renderTextures(void) {
glBindFramebuffer(GL_FRAMEBUFFER, fbo); // Bind our frame buffer for rendering
glPushAttrib(GL_VIEWPORT_BIT | GL_ENABLE_BIT); // Push our glEnable and glViewport states
glViewport(0, 0, window_width, window_height); // Set the size of the frame buffer view port
glDrawBuffer(GL_COLOR_ATTACHMENT0);
glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // Set the clear colour
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);// Clear the depth and colour buffers
glLoadIdentity();// Reset the modelview matrix
glTranslatef(0.0f, 0.0f, -5.0f);
//Add ambient light
GLfloat ambientColor[] = {0.2f, 0.2f, 0.2f, 1.0f}; //Color(0.2, 0.2, 0.2)
glLightModelfv(GL_LIGHT_MODEL_AMBIENT, ambientColor);
//Add positioned light
GLfloat lightColor0[] = {0.5f, 0.5f, 0.5f, 1.0f}; //Color (0.5, 0.5, 0.5)
GLfloat lightPos0[] = {4.0f, 0.0f, 8.0f, 1.0f}; //Positioned at (4, 0, 8)
glLightfv(GL_LIGHT0, GL_DIFFUSE, lightColor0);
glLightfv(GL_LIGHT0, GL_POSITION, lightPos0);
//Add directed light
GLfloat lightColor1[] = {0.5f, 0.2f, 0.2f, 1.0f}; //Color (0.5, 0.2, 0.2)
//Coming from the direction (-1, 0.5, 0.5)
GLfloat lightPos1[] = {-1.0f, 0.5f, 0.5f, 0.0f};
glLightfv(GL_LIGHT1, GL_DIFFUSE, lightColor1);
glLightfv(GL_LIGHT1, GL_POSITION, lightPos1);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_LIGHT1);
glEnable(GL_DEPTH_TEST);
glutSolidTeapot(2.0);
glColor3f(0.1,0.2,0.7);
glDrawBuffer(GL_COLOR_ATTACHMENT1);
glClearColor(0.5f, 0.5f, 0.0f, 1.0f); // Set the clear colour
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);// Clear the depth and colour buffers
glLoadIdentity();// Reset the modelview matrix
glTranslatef(0.0f, 0.0f, -5.0f);
glutSolidTorus(0.80, 1.6, 50, 100);
glColorMaterial ( GL_FRONT_AND_BACK, GL_EMISSION ) ;
glEnable ( GL_COLOR_MATERIAL ) ;
glDrawBuffer(GL_COLOR_ATTACHMENT2);
glClearColor(0.5f, 0.0f, 0.0f, 1.0f); // Set the clear colour
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);// Clear the depth and colour buffers
glLoadIdentity();// Reset the modelview matrix
glTranslatef(0.0f, 0.0f, -2.0f);
glutSolidTetrahedron();
glColorMaterial ( GL_FRONT_AND_BACK, GL_EMISSION ) ;
glEnable ( GL_COLOR_MATERIAL ) ;
glDrawBuffer(GL_COLOR_ATTACHMENT3);
glClearColor(0.5f, 0.0f, 0.3f, 1.0f); // Set the clear colour
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);// Clear the depth and colour buffers
glLoadIdentity();// Reset the modelview matrix
glTranslatef(0.0f, 0.0f, -2.0f);
glutSolidOctahedron();
glColorMaterial ( GL_FRONT_AND_BACK, GL_EMISSION ) ;
glEnable ( GL_COLOR_MATERIAL ) ;
glBindFramebuffer(GL_FRAMEBUFFER, 0); // Unbind our ture
glActiveTexture(GL_TEXTURE0);
//glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, fbo_texture0);
glUniform1i(glGetUniformLocation(shaderProgram, "tex0"), 0);
glActiveTexture(GL_TEXTURE1);
//glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, fbo_texture1);
glUniform1i(glGetUniformLocation(shaderProgram, "tex1"), 1);
glActiveTexture(GL_TEXTURE2);
//glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, fbo_texture2);
glUniform1i(glGetUniformLocation(shaderProgram, "tex2"), 2);
glActiveTexture(GL_TEXTURE3);
//glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, fbo_texture3);
glUniform1i(glGetUniformLocation(shaderProgram, "tex3"), 3);
glPopAttrib(); // Restore our glEnable and glViewport states
glutSwapBuffers();
}
static char* textFileRead(const char *fileName) {
char* text;
if (fileName != NULL) {
FILE *file = fopen(fileName, "rt");
if (file != NULL) {
fseek(file, 0, SEEK_END);
int count = ftell(file);
rewind(file);
if (count > 0) {
text = (char*)malloc(sizeof(char) * (count + 1));
count = fread(text, sizeof(char), count, file);
text[count] = '\0';
}
fclose(file);
}
}
return text;
}
void initShader(){
char* vsSource = textFileRead("./shader/multitexture.vs");
char* fsSource = textFileRead("./shader/multitexture.fs");
printf("%s\n",fsSource);
vertexShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertexShader, 1, (const GLchar **)(&vsSource), NULL);
glCompileShader(vertexShader);
printInfoLog(vertexShader);
fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, (const GLchar **)(&fsSource), NULL);
glCompileShader(fragmentShader);
printInfoLog(fragmentShader);
delete [] vsSource;
delete [] fsSource;
shaderProgram = glCreateProgram();
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
glLinkProgram(shaderProgram);
}
void display (void) {
keyOperations(); // Perform any key presses
glUseProgram(0);
renderTextures(); // Render our teapot scene into our frame buffer
GLsync s = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0);
glUseProgram(shaderProgram);
glClearColor(0.0f, 1.0f, 0.0f, 1.0f); // Clear the background of our window to red
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); //Clear the colour buffer (more buffers later on)
glLoadIdentity(); // Load the Identity Matrix to reset our drawing locations
glTranslatef(-4.7f, 1.0f, -4.0f);
glWaitSync(s, 0, GL_TIMEOUT_IGNORED);
glDeleteSync(s);
glBindTexture(GL_TEXTURE_2D, fbo_texture0); // Bind our frame buffer ture
glBegin(GL_QUADS);
glColor4f(1, 1, 1, 1);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, 0.0f); // The bottom left corner
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 0.0f); // The top left corner
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, 1.0f, 0.0f); // The top right corner
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, -1.0f, 0.0f); // The bottom right corner
glEnd();
glBindTexture(GL_TEXTURE_2D, 0); // Unbind any tures
glLoadIdentity();
glTranslatef(-2.5f, 1.0f, -4.0f);
glBindTexture(GL_TEXTURE_2D, fbo_texture1); // Bind our frame buffer ture
glBegin(GL_QUADS);
glColor4f(1, 1, 1, 1);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, 0.0f); // The bottom left corner
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 0.0f); // The top left corner
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, 1.0f, 0.0f); // The top right corner
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, -1.0f, 0.0f); // The bottom right corner
glEnd();
glBindTexture(GL_TEXTURE_2D, 0); // Unbind any tures
glLoadIdentity();
glTranslatef(-0.3f, 1.0f, -4.0f);
glBindTexture(GL_TEXTURE_2D, fbo_texture2); // Bind our frame buffer ture
glBegin(GL_QUADS);
glColor4f(1, 1, 1, 1);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, 0.0f); // The bottom left corner
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 0.0f); // The top left corner
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, 1.0f, 0.0f); // The top right corner
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, -1.0f, 0.0f); // The bottom right corner
glEnd();
glBindTexture(GL_TEXTURE_2D, 0); // Unbind any tures
glLoadIdentity();
glTranslatef(1.9f, 1.0f, -4.0f);
glBindTexture(GL_TEXTURE_2D, fbo_texture3); // Bind our frame buffer ture
glBegin(GL_QUADS);
glColor4f(1, 1, 1, 1);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, 0.0f); // The bottom left corner
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 0.0f); // The top left corner
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, 1.0f, 0.0f); // The top right corner
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, -1.0f, 0.0f); // The bottom right corner
glEnd();
glBindTexture(GL_TEXTURE_2D, 0); // Unbind any tures
glLoadIdentity();
glTranslatef(4.1f, 1.0f, -4.0f);
glBindTexture(GL_TEXTURE_2D, fbo_texture4); // Bind our frame buffer ture
glBegin(GL_QUADS);
glColor4f(1, 1, 1, 1);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, 0.0f); // The bottom left corner
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 0.0f); // The top left corner
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, 1.0f, 0.0f); // The top right corner
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, -1.0f, 0.0f); // The bottom right corner
glEnd();
glBindTexture(GL_TEXTURE_2D, 0); // Unbind any tures
glutSwapBuffers();
}
void reshape (int width, int height) {
glViewport(0, 0, (GLsizei)width, (GLsizei)height); // Set our viewport to the size of our window
glMatrixMode(GL_PROJECTION); // Switch to the projection matrix so that we can manipulate how our scene is viewed
glLoadIdentity(); // Reset the projection matrix to the identity matrix so that we don't get any artifacts (cleaning up)
gluPerspective(60, (GLfloat)width / (GLfloat)height, 1.0, 100.0); // Set the Field of view angle (in degrees), the aspect ratio of our window, and the new and far planes
glMatrixMode(GL_MODELVIEW); // Switch back to the model view matrix, so that we can start drawing shapes correctly
}
void keyPressed (unsigned char key, int x, int y) {
keyStates[key] = true; // Set the state of the current key to pressed
}
void keyUp (unsigned char key, int x, int y) {
keyStates[key] = false; // Set the state of the current key to not pressed
}
int main (int argc, char **argv) {
glutInit(&argc, argv); // Initialize GLUT
glutInitDisplayMode (GLUT_DOUBLE | GLUT_DEPTH | GLUT_RGBA); // Set up a basic display buffer (only single buffered for now)
glutInitWindowSize (1280, 500); // Set the width and height of the window
glutInitWindowPosition (100, 100); // Set the position of the window
glutCreateWindow ("OpenGL FBO"); // Set the title for the window
if (GLEW_OK != glewInit()) {
std::cout << "Couldn't initialize GLEW" << std::endl;
exit(0);
}
initShader();
init();
glutDisplayFunc(display); // Tell GLUT to use the method "display" for rendering
glutIdleFunc(display); // Tell GLUT to use the method "display" for rendering
glutReshapeFunc(reshape); // Tell GLUT to use the method "reshape" for reshaping
glutKeyboardFunc(keyPressed); // Tell GLUT to use the method "keyPressed" for key presses
glutKeyboardUpFunc(keyUp); // Tell GLUT to use the method "keyUp" for key up events
glutMainLoop(); // Enter GLUT's main loop
}
以下是顶点着色器：
void main(void)
{
gl_TexCoord[0] = gl_MultiTexCoord0;
gl_Position = ftransform();
}
这是片段着色器：
uniform sampler2D tex0;
uniform sampler2D tex1;
uniform sampler2D tex2;
uniform sampler2D tex3;
void main(void)
{
gl_FragColor = texture2D(tex0, gl_TexCoord[0].st);
}
编辑 #1
按照@Damon的建议修改代码（代码也已经编辑），以下是结果的截图：
图像 3
现在，我真的不知道问题到底是什么。我尝试将片段着色器更改为访问另一个纹理，例如gl_FragColor = texture2D(tex2, gl_TexCoord[0].st);，但我仍然得到与上面相同的显示效果。所以我认为这绝对不是模型视图/投影问题。
编辑 #2
问题仍然不清楚。但是，我尝试在程序中只给出一个glActiveTexture(GL_TEXTUREn);命令，并注释掉其他glActiveTexture命令（没有着色器修改），并获得了以下结果：
图像 4 只有glActiveTexture(GL_TEXTURE0);被激活。
图像 5 只有glActiveTexture(GL_TEXTURE1);被激活。
图像 6 只有glActiveTexture(GL_TEXTURE2);被激活。
图像 7 只有glActiveTexture(GL_TEXTURE3);被激活。
当至少有 2 个glActiveTexture(GL_TEXTUREn); 被激活时，我得到与 图像 5 相同的结果。这让我想知道问题究竟是什么。