After getting the first example program compiled from the 8th edition OpenGL Programming Guide after many alterations suggested by many sites, I am the proud owner of a black box - a vast improvement from the hours before, but it's embarrassing to admit that I've watch most of this with a debugger and unless something basic is wrong with the program, I have no clue where to look. Other OpenGL examples have run, but I'm trying to get the first example in the new book to run.
My box:
john@zerofluid:~/Downloads$ glxinfo | grep OpenGL
OpenGL vendor string: NVIDIA Corporation
OpenGL renderer string: GeForce GT 610/PCIe/SSE2
OpenGL version string: 4.3.0 NVIDIA 313.30
OpenGL shading language version string: 4.30 NVIDIA via Cg compiler
OpenGL extensions:
Linux zerofluid 3.8.0-26-generic #38-Ubuntu SMP Mon Jun 17 21:43:33 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux (latest 13.04 Ubuntu)
I have a problem - it's way too much code to post here, but it is the first example of the book - as small as it gets and I have no idea of where the problem really is. It would be cool if someone actually wants to help - I'd feed it back to the author of the book. Yes, the LoadShader was found elsewhere and might be the problem, but it was supposed to be a solution. It's kind of hard to have any faith in the book when I can't get the first example to compile.
It can be found here: https://github.com/kestess/opengl8thfirstexample.git
it's way too much code to post here
Not really.
Try this:
#include <GL/glew.h>
#include <GL/freeglut.h>
#include <vector>
#include <iostream>
struct Program
{
static GLuint Load( const char* vert, const char* geom, const char* frag )
{
GLuint prog = glCreateProgram();
if( vert ) AttachShader( prog, GL_VERTEX_SHADER, vert );
if( geom ) AttachShader( prog, GL_GEOMETRY_SHADER, geom );
if( frag ) AttachShader( prog, GL_FRAGMENT_SHADER, frag );
glLinkProgram( prog );
CheckStatus( prog );
return prog;
}
private:
static void CheckStatus( GLuint obj )
{
GLint status = GL_FALSE, len = 10;
if( glIsShader(obj) ) glGetShaderiv( obj, GL_COMPILE_STATUS, &status );
if( glIsProgram(obj) ) glGetProgramiv( obj, GL_LINK_STATUS, &status );
if( status == GL_TRUE ) return;
if( glIsShader(obj) ) glGetShaderiv( obj, GL_INFO_LOG_LENGTH, &len );
if( glIsProgram(obj) ) glGetProgramiv( obj, GL_INFO_LOG_LENGTH, &len );
std::vector< char > log( len, 'X' );
if( glIsShader(obj) ) glGetShaderInfoLog( obj, len, NULL, &log[0] );
if( glIsProgram(obj) ) glGetProgramInfoLog( obj, len, NULL, &log[0] );
std::cerr << &log[0] << std::endl;
exit( -1 );
}
static void AttachShader( GLuint program, GLenum type, const char* src )
{
GLuint shader = glCreateShader( type );
glShaderSource( shader, 1, &src, NULL );
glCompileShader( shader );
CheckStatus( shader );
glAttachShader( program, shader );
glDeleteShader( shader );
}
};
#define GLSL(version, shader) "#version " #version "\n" #shader
const char* vert = GLSL
(
400 core,
layout( location = 0 ) in vec4 vPosition;
void main()
{
gl_Position = vPosition;
}
);
const char* frag = GLSL
(
400 core,
out vec4 fColor;
void main()
{
fColor = vec4( 0.0, 0.0, 1.0, 1.0 );
}
);
enum VAO_IDs { Triangles, NumVAOs };
enum Buffer_IDs { ArrayBuffer, NumBuffers };
enum Attrib_IDs { vPosition = 0 };
GLuint VAOs[NumVAOs];
GLuint Buffers[NumBuffers];
const GLuint NumVertices = 6;
void init(void)
{
glGenVertexArrays(NumVAOs, VAOs);
glBindVertexArray(VAOs[Triangles]);
GLfloat vertices[NumVertices][2] = {
{ -0.90, -0.90 }, // Triangle 1
{ 0.85, -0.90 },
{ -0.90, 0.85 },
{ 0.90, -0.85 }, // Triangle 2
{ 0.90, 0.90 },
{ -0.85, 0.90 }
};
glGenBuffers(NumBuffers, Buffers);
glBindBuffer(GL_ARRAY_BUFFER, Buffers[ArrayBuffer]);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
GLuint program = Program::Load( vert, NULL, frag );
glUseProgram(program);
glVertexAttribPointer(vPosition, 2, GL_FLOAT, GL_FALSE, 0, (void*)(0) );
glEnableVertexAttribArray(vPosition);
}
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glBindVertexArray(VAOs[Triangles]);
glDrawArrays(GL_TRIANGLES, 0, NumVertices);
glutSwapBuffers();
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE );
glutInitWindowSize(512, 512);
glutInitContextVersion(4, 0);
glutInitContextProfile(GLUT_CORE_PROFILE);
glutCreateWindow(argv[0]);
glewExperimental = GL_TRUE;
if( GLEW_OK != glewInit() )
exit(EXIT_FAILURE);
init();
glutDisplayFunc(display);
glutMainLoop();
}
No reason to request a 4.3
context if you're using #version 400 core
.
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