我在“tut2.c”中有这个程序：
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stddef.h>
#include <GL/glew.h>
#include <GL/glfw.h>
GLuint vbo[2];
const GLfloat diamond[4][2] = {
{ 0.0, 0.5 }, //top point
{ 0.5, 0.0 }, //right
{ 0.0, -0.5 }, // bottom
{ -0.5, 0.5 }}; //left
const GLfloat colors[4][3] = {
{1.0, 0.0, 0.0},
{0.0, 1.0, 0.0},
{0.0, 0.0, 1.0},
{1.0, 1.0, 1.0}};
GLchar *vertexsource, *fragmentsource;
GLuint vertexshader, fragmentshader;
GLuint shaderprogram;
char* filetobuf(char *file) //will reac a file into an allocated char pointer buffer
{
FILE *fptr;
long length;
char *buf;
//opening the file
fptr = fopen(file, "rb");
if(!fptr)
{
fprintf(stderr, "failed to open %s\n", file);
return NULL;
}
fseek(fptr,0,SEEK_END); //go to the end of the file
length = ftell(fptr); //count bytes in "fptr" file
buf = (char*)malloc(length+1); //allocate a buffer for all the file and +1 for the null terminator
fseek(fptr, 0, SEEK_SET); //SEEK_SET = Begging of file >> go to hte start of the file
fclose(fptr); //close the file
buf[length] = 0; //null terminator
return buf;
}
void check(char *where)
{
char *what;
int err = glGetError();
if(!err)
{
printf("OpenGL error integer: %d", err);
return;
}
if(err == "GL_INVALID_ENUM")
what = "GL_INVALID_ENUM";
else if(err == "GL_INVALID_VALUE")
what = "GL_INVALID_VALUE";
else if(err == "GL_INVALID_OPERATION")
what = "GL_INVALID_OPERATION";
else if(err == "GL_INVALID_FRAMEBUFFER_OPERATION")
what = "GL_INVALID_FRAMEBUFFER_OPERATION";
else if(err == "GL_OUT_OF_MEMORY")
what = "GL_OUT_OF_MEMORY";
else
what = "Unkown error";
fprintf(stderr, "Error (%d) %s at %s\n, err, what, where");
exit(1);
}
void SetupShaders(void)
{
char text[1000];
int length;
fprintf(stderr, "Set up shaders\n"); //allocate and assign 2 Vertex Buffer Objects to our handle
//reading files and placing them into buffers
vertexsource = filetobuf("tut2.vert");
fragmentsource = filetobuf("tut2.frag");
//assign to our shaders a name
vertexshader = glCreateShader(GL_VERTEX_SHADER);
fragmentshader = glCreateShader(GL_FRAGMENT_SHADER);
//associate the source code buffers with each handle
glShaderSource(vertexshader, 1, (const GLchar**)&vertexsource, 0);
glShaderSource(fragmentshader, 1, (const GLchar**)&fragmentsource, 0);
//compile our fragment and vertex shaders programs
glCompileShader(fragmentshader);
glCompileShader(vertexshader);
shaderprogram = glCreateProgram(); //assign our program handle a "name"
//attaching shaders to our program
glAttachShader(shaderprogram, vertexshader);
glAttachShader(shaderprogram, fragmentshader);
//link our program
glLinkProgram(shaderprogram);
glGetProgramInfoLog(shaderprogram, 1000, &length, text);
if(length > 0)
fprintf(stderr, "Validate Shader\n%s\n", text);
glUseProgram(shaderprogram); // set program as being actively used
}
void SetupGeometry(void)
{
fprintf(stderr, "Setup vertices\n");
glGenBuffers(2,vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo[0]);
glEnableVertexAttribArray(0);
glBufferData(GL_ARRAY_BUFFER, 8* sizeof(GLfloat), diamond, GL_STATIC_DRAW);
glVertexAttribPointer((GLuint)0,2, GL_FLOAT,GL_FALSE, 0,0);
glBindBuffer(GL_ARRAY_BUFFER, vbo[1]);
glEnableVertexAttribArray(1);
glBufferData(GL_ARRAY_BUFFER, 12* sizeof(GLfloat), colors, GL_STATIC_DRAW);
glVertexAttribPointer((GLuint)1,3, GL_FLOAT,GL_FALSE, 0,0);
glBindAttribLocation(shaderprogram, 0, "in_Position");
glBindAttribLocation(shaderprogram, 1, "in_Color");
}
void Render(void)
{
glClearColor(0.0,0.0,0.0,0.1);
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(GL_LINE_LOOP,0,4);
check("Test Point");
glFlush();
}
int main(void)
{
int running = GL_TRUE;
if(!glfwInit())
{
exit(EXIT_FAILURE);
}
if( !glfwOpenWindow(600,600,0,0,0,0,0,0, GLFW_WINDOW))
{
glfwTerminate();
exit(EXIT_FAILURE);
}
glewInit();
SetupShaders();
SetupGeometry();
//Main loop
while(running)
{
Render();
glfwSwapBuffers();
running = !glfwGetKey(GLFW_KEY_ESC) && glfwGetWindowParam(GLFW_OPENED);
}
glfwTerminate();
exit(EXIT_SUCCESS);
}
此文件“tut2.vert”和“tut2.frag”
tut2.frag
#version 150
precision highp float;
in vec3 ex_Color;
out vec4 gl_FragColor;
void main(void)
{
gl_FragColor = vec4(ex_Color, 1.0);
}
tut2.vert
#version 150
in vec2 in_Position;
in vec3 in_Color;
out vec3 ex_Color;
void main(void)
{
gl_Position = vec4(in_Position.x, in_Position.y, 0.0, 1.0);
ex_Color = in_Color;
}
我用
编译所有内容gcc tut2.c -o tut2 -lglfw -lGLEW -lGLU -lGL
但是当我运行该程序时，我得到了一个我无法解决的奇怪错误：
Set up shaders
Validate Shader
Vertex info
-----------
0(1) : error C0000: syntax error, unexpected $undefined at token "<undefined>"
Fragment info
-------------
0(1) : error C0000: syntax error, unexpected $undefined at token "<undefined>"
Setup vertices
Segmentation fault (core dumped)
有什么帮助吗？
答案 0 :(得分：1)
你在一个程序中遇到两个问题，它们没有关系。首先你的着色器不能编译：
Set up shaders Validate Shader Vertex info ----------- 0(1) : error C0000: syntax error, unexpected $undefined at token "<undefined>" Fragment info ------------- 0(1) : error C0000: syntax error, unexpected $undefined at token "<undefined>"
所以你需要修复着色器。
然后你在SetupGeometry函数的某个地方访问了无效的地址（你之前可能还有一个缓冲区溢出，现在会触发一个错误）。
Setup vertices Segmentation fault (core dumped)
当你说你需要修复着色器时，我的意思是你应该检查着色器加载代码。基本上，GLSL编译器在一开始就报告了一些无效数据。
着色器加载代码缺少一些至关重要的内容：阅读步骤：
char* filetobuf(char *file) //will reac a file into an allocated char pointer buffer
{
FILE *fptr;
long length;
char *buf;
//opening the file
fptr = fopen(file, "rb");
if(!fptr)
{
fprintf(stderr, "failed to open %s\n", file);
return NULL;
}
fseek(fptr,0,SEEK_END);
length = ftell(fptr);
您可以使用fstat(fileno(fptr), statbuf)来检索文件大小，而不是fseek，ftell方法。请参阅统计系统调用手册。
buf = (char*)malloc(length+1);
在C中，您不会在作业中投射void*。只需指定裸void*指针即可。这与C ++不同
fseek(fptr, 0, SEEK_SET);
在这里，您应该阅读一些数据，例如fread(fptr, 1 length, buf);
fclose(fptr); //close the file
buf[length] = 0; //null terminator
return buf;
}
在上传到OpenGL后，您还需要free(…)着色器源缓冲区。
答案 1 :(得分：0)
#version 150
// It was expressed that some drivers required this next line to function properly precision highp float;
in vec3 ex_Color;
out vec4 ex_FragColor;
void main(void) {
// Pass through our original color with full opacity.
ex_FragColor = vec4(ex_Color,1.0);
}
感谢Christian Rau