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我写了一个测试程序，用于测试渲染帧缓冲纹理。在函数render_texture（）中，我想渲染一个三角形到一个纹理，但是当我在显示函数中显示渲染的纹理时，我只得到一个简单的黄色方块。opengl：渲染纹理出错
#include "GL/glew.h"
#include "GL/glext.h"
#include "GL/glu.h"
#include "GL/freeglut.h"
#include <cstdio>
uint16_t tex_width = 75;
uint16_t tex_height = 24;
GLuint texture;
int w1;
int h1;
void orthogonalStart (int w, int h) {
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
gluOrtho2D(0, w, 0, h);
glScalef(1, -1, 1);
glTranslatef(0, -h1, 0);
glMatrixMode(GL_MODELVIEW);
}
void orthogonalEnd (void) {
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
}
void display (void) {
glClearColor (0.0,0.0,0.0,1.0);
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
orthogonalStart(w1, h1);
glBegin(GL_QUADS);
glTexCoord2f(0, 0); glVertex2f(125, 125);
glTexCoord2f(0, 1); glVertex2f(125, 125+tex_height);
glTexCoord2f(1, 1); glVertex2f(125+tex_width, 125+tex_height);
glTexCoord2f(1, 0); glVertex2f(125+tex_width, 125);
glEnd();
orthogonalEnd();
glutSwapBuffers();
}
void reshape (int w, int h) {
glViewport (0, 0, (GLsizei)w, (GLsizei)h);
glMatrixMode (GL_PROJECTION);
glLoadIdentity();
gluPerspective (60, (GLfloat)w/(GLfloat)h, 0.1, 1000.0);
w1 = w;
h1 = h;
glMatrixMode (GL_MODELVIEW);
}
void render_texture()
{
GLuint framebuffer = 0;
glGenFramebuffers(1, &framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, tex_width, tex_height, 0, GL_RGBA,
GL_UNSIGNED_BYTE, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
GLenum draw_buffers[1] = {GL_COLOR_ATTACHMENT0};
glDrawBuffers(1, draw_buffers);
if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
{
fprintf(stderr, "[render_texture] Fehler im Framebuffer\n");
exit(1);
}
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
glViewport(0, 0, tex_width, tex_height);
glClearColor (0.0,0.0,0.0,1.0);
orthogonalStart(tex_width, tex_height);
glColor4f(1, 1, 0, 0);
glBegin(GL_TRIANGLES);
glVertex2f(0.f,0.f);
glVertex2f(tex_width, 0.0f);
glVertex2f(tex_width, (GLfloat)tex_height/2.f);
//glVertex2f(tex_width-(GLfloat)tex_height/2.f, tex_height);
//glVertex2f(0, tex_height);
glEnd();
orthogonalEnd();
glBindFramebuffer(GL_FRAMEBUFFER, 0);
}
int main (int argc, char **argv) {
glutInit (&argc, argv);
glutInitDisplayMode (GLUT_DOUBLE | GLUT_DEPTH | GLUT_RGBA);
glutInitWindowSize (500, 500);
glutInitWindowPosition (100, 100);
glutCreateWindow ("");
glutDisplayFunc (display);
glutIdleFunc (display);
glutReshapeFunc (reshape);
glewExperimental=true;
GLenum err=glewInit();
if(err!=GLEW_OK)
{
//Problem: glewInit failed, something is seriously wrong.
fprintf(stderr, "glewInit failed, aborting.\n");
}
render_texture();
glutMainLoop();
return 0;
}
编辑1：我已经更新了代码，现在我只是黑屏
#include "GL/glew.h"
#include "GL/glext.h"
#include "GL/glu.h"
#include "GL/freeglut.h"
#include <cstdio>
uint16_t tex_width = 75;
uint16_t tex_height = 24;
GLuint texture;
void orthogonalStart (int w, int h) {
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
gluOrtho2D(0, w, 0, h);
glScalef(1, -1, 1);
glTranslatef(0, -glutGet(GLUT_WINDOW_HEIGHT), 0);
glMatrixMode(GL_MODELVIEW);
}
void orthogonalEnd (void) {
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
}
void display (void) {
glClearColor (0.0,0.0,0.0,1.0);
glClear (GL_COLOR_BUFFER_BIT);
glLoadIdentity();
orthogonalStart(glutGet(GLUT_WINDOW_WIDTH), glutGet(GLUT_WINDOW_HEIGHT));
glColor3f(1,1,1);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, texture);
glBegin(GL_QUADS);
glTexCoord2f(0, 0); glVertex2f(125, 125);
glTexCoord2f(0, 1); glVertex2f(125, 125+tex_height);
glTexCoord2f(1, 1); glVertex2f(125+tex_width, 125+tex_height);
glTexCoord2f(1, 0); glVertex2f(125+tex_width, 125);
glEnd();
glDisable(GL_TEXTURE_2D);
orthogonalEnd();
glutSwapBuffers();
}
void reshape (int w, int h) {
glViewport (0, 0, (GLsizei)w, (GLsizei)h);
glMatrixMode (GL_PROJECTION);
glLoadIdentity();
gluPerspective (60, (GLfloat)w/(GLfloat)h, 0.1, 1000.0);
glMatrixMode (GL_MODELVIEW);
}
void render_texture()
{
GLuint framebuffer = 0;
glGenFramebuffers(1, &framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, tex_width, tex_height, 0, GL_RGBA,
GL_UNSIGNED_BYTE, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
GLenum draw_buffers[1] = {GL_COLOR_ATTACHMENT0};
glDrawBuffers(1, draw_buffers);
if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
{
fprintf(stderr, "[render_texture] Fehler im Framebuffer\n");
exit(1);
}
glViewport(0, 0, tex_width, tex_height);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
orthogonalStart(tex_width, tex_height);
glColor4f(1, 1, 0, 0);
glBegin(GL_TRIANGLES);
glVertex2f(0.f,0.f);
glVertex2f(tex_width, 0.0f);
glVertex2f(tex_width, (GLfloat)tex_height/2.f);
//glVertex2f(tex_width-(GLfloat)tex_height/2.f, tex_height);
//glVertex2f(0, tex_height);
glEnd();
orthogonalEnd();
glBindFramebuffer(GL_FRAMEBUFFER, 0);
}
int main (int argc, char **argv) {
glutInit (&argc, argv);
glutInitContextVersion(3, 1);
glutInitContextProfile(GLUT_CORE_PROFILE);
glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGBA);
glutInitWindowSize (500, 500);
glutCreateWindow ("");
glutDisplayFunc (display);
glutIdleFunc (display);
glutReshapeFunc (reshape);
glewExperimental=true;
GLenum err=glewInit();
if(err!=GLEW_OK)
{
//Problem: glewInit failed, something is seriously wrong.
fprintf(stderr, "glewInit failed, aborting.\n");
}
//glEnable(GL_TEXTURE_2D);
render_texture();
glutMainLoop();
return 0;
}
只是我的标准建议：将代码从重塑移动到显示器中，您可以节省推送和弹出矩阵的麻烦。使用glutGet（GLUT_WINDOW_ {WIDTH，HEIGHT}）来获得窗口大小。 – datenwolf