OpenGL Perspective matrices not working - c++

Question

I'm new to both stack overflow and OpenGL.
I'm trying to create my first little 3d program with custom shaders, but i have a problem with the various matrices that are required. I don't know exactly what causes complete black screen, if it is that i load uniforms incorrectly or that I'm failing at calculating the matrices. Anyway, I post the code down here and if anyone can help it would be amazing.
Main Cpp file
#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <GL\glew.h>
#include <GL\glut.h>
#include <glm\glm.hpp>
#include <glm\vec3.hpp>
#include <glm\mat4x4.hpp>
#include <glm\gtc\matrix_transform.hpp>
#include <glm\gtc\type_ptr.hpp>
GLuint programID, vbo;
using namespace glm;
void loadShaders(){
char vertex_file_path[] = "vertex.glsl";
char fragment_file_path[] = "fragment.glsl";
// Create the shaders
GLuint VertexShaderID = glCreateShader(GL_VERTEX_SHADER);
GLuint FragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);
// Read the Vertex Shader code from the file
std::string VertexShaderCode;
std::ifstream VertexShaderStream(vertex_file_path);
if (VertexShaderStream.is_open()){
std::string Line = "";
while (std::getline(VertexShaderStream, Line))
VertexShaderCode += "\n" + Line;
VertexShaderStream.close();
}
else{
printf("Impossible to open %s. Are you in the right directory ? Don't forget to read the FAQ !\n", vertex_file_path);
getchar();
throw new std::runtime_error("Shaders not found");
}
// Read the Fragment Shader code from the file
std::string FragmentShaderCode;
std::ifstream FragmentShaderStream(fragment_file_path, std::ios::in);
if (FragmentShaderStream.is_open()){
std::string Line = "";
while (std::getline(FragmentShaderStream, Line))
FragmentShaderCode += "\n" + Line;
FragmentShaderStream.close();
}
GLint Result = GL_FALSE;
int InfoLogLength;
// Compile Vertex Shader
printf("Compiling shader : %s\n", vertex_file_path);
char const * VertexSourcePointer = VertexShaderCode.c_str();
glShaderSource(VertexShaderID, 1, &VertexSourcePointer, NULL);
glCompileShader(VertexShaderID);
// Check Vertex Shader
glGetShaderiv(VertexShaderID, GL_COMPILE_STATUS, &Result);
if (Result == GL_FALSE){
glGetShaderiv(VertexShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
char * VertexShaderErrorMessage = new char[InfoLogLength + 1];
glGetShaderInfoLog(VertexShaderID, InfoLogLength, NULL, VertexShaderErrorMessage);
std::cout << VertexShaderErrorMessage << std::endl;
printf("Could not compile vertex shader: %s\n", VertexShaderErrorMessage);
getchar();
throw new std::runtime_error("Could not compile vertex shader");
}
// Compile Fragment Shader
std::cout << "Compiling shader : " << fragment_file_path << std::endl;
char const * FragmentSourcePointer = FragmentShaderCode.c_str();
glShaderSource(FragmentShaderID, 1, &FragmentSourcePointer, NULL);
glCompileShader(FragmentShaderID);
// Check Fragment Shader
glGetShaderiv(FragmentShaderID, GL_COMPILE_STATUS, &Result);
if (Result == GL_FALSE){
glGetShaderiv(FragmentShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
char * FragmentShaderErrorMessage = new char[InfoLogLength + 1];
glGetShaderInfoLog(FragmentShaderID, InfoLogLength, NULL, FragmentShaderErrorMessage);
printf("Could not compile fragment shader: %s\n", FragmentShaderErrorMessage);
getchar();
throw new std::runtime_error("Could not compile fragment shader");
}
// Link the program
printf("Linking program\n");
GLuint ProgramID = glCreateProgram();
glAttachShader(ProgramID, VertexShaderID);
glAttachShader(ProgramID, FragmentShaderID);
glLinkProgram(ProgramID);
// Check the program
glGetProgramiv(ProgramID, GL_LINK_STATUS, &Result);
if (Result == GL_FALSE){
glGetProgramiv(ProgramID, GL_INFO_LOG_LENGTH, &InfoLogLength);
std::vector<char> ProgramErrorMessage(InfoLogLength + 1);
glGetProgramInfoLog(ProgramID, InfoLogLength, NULL, &ProgramErrorMessage[0]);
printf("%s\n", &ProgramErrorMessage[0]);
throw new std::runtime_error("Could not compile program");
}
glDetachShader(ProgramID, VertexShaderID);
glDetachShader(ProgramID, FragmentShaderID);
glDeleteShader(VertexShaderID);
glDeleteShader(FragmentShaderID);
programID = ProgramID;
}
void loadMatrices(){
GLuint modelLoc = glGetUniformLocation(programID, "model");
GLuint viewLoc = glGetUniformLocation(programID, "view");
GLuint projLoc = glGetUniformLocation(programID, "projection");
mat4 model = scale(mat4(1.0f), vec3(1.0f));
mat4 view = lookAt(vec3(0.0f, 0.0f, 2.0f), vec3(0.0f, 0.0f, 0.0f), vec3(0.0f, 1.0f, 0.0f));
mat4 projection = perspective(45.0f, 16.0f / 9.0f, 0.01f, 100.0f);
glUniformMatrix4fv(modelLoc, 1, GL_FALSE, value_ptr(model));
glUniformMatrix4fv(viewLoc, 1, GL_FALSE, value_ptr(view));
glUniformMatrix4fv(projLoc, 1, GL_FALSE, value_ptr(projection));
}
void renderLoop(){
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glUseProgram(programID);
glEnableVertexAttribArray(0);
glVertexAttribPointer(
0,
3,
GL_FLOAT,
GL_FALSE,
0,
(void *) 0
);
glDrawArrays(GL_TRIANGLES, 0, 3);
glDisableVertexAttribArray(0);
glutSwapBuffers();
}
int _tmain(int argc, _TCHAR* argv[])
{
int MY_ZERO = 0;
glutInit(&MY_ZERO, NULL);
glutInitWindowSize(1280, 720);
glutInitDisplayMode(GLUT_DOBULE);
glutCreateWindow("Test");
glewExperimental = true;
glewInit();
glutIdleFunc(renderLoop);
glutDisplayFunc(renderLoop);
glMatrixMode(GL_PROJECTION);
glEnable(GL_DEPTH_TEST);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Nice perspective corrections
glDepthFunc(GL_LEQUAL);
glMatrixMode(GL_MODELVIEW);
glEnable(GL_BLEND);
gluPerspective(75.0f, 16.0f / 9, 0.1f, 100.0f);
std::cout << "Setting blendFunc..." << std::endl;
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
loadShaders();
loadMatrices();
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
float vals[] = {
0.0f, 1.0f, -10.0f,
1.0f, 1.0f, -10.0f,
1.0f, 0.0f, -10.0f
};
glBufferData(GL_ARRAY_BUFFER, sizeof(vals), vals, GL_STATIC_DRAW);
glutMainLoop();
system("pause");
return 0;
}
Vertex Shader
layout (location = 0) in vec3 pos;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main(){
gl_Position = projection * vec4(pos, 1.0f);
}
Fragment Shader
void main(){
gl_FragColor = vec4(0.0, 0.0, 1.0, 1.0);
}

Answer 1

There are several general aspects of the code which need improvement; e.g.
⊗ it can throw but doesn't catch and cleanup:
// there's no try/catch block enclosing this
throw new std::runtime_error("Could not compile vertex shader");
⊗ it's ready to leak:
char * VertexShaderErrorMessage = new char[InfoLogLength + 1];
/* ... */
throw new std::runtime_error("Could not compile vertex shader");
⊗ it needlessly consumes CPU and GPU time
glutIdleFunc(renderLoop); // boosts the frame rate for performance
// meters only
and so on, e.g. unrolling the shader creation and error handling loop violates DRY.
From an OpenGL-specific pov, there are several things which are not ok.
⊗ This
mat4 view = lookAt(vec3(0.0f, 0.0f, 2.0f),
vec3(0.0f, 0.0f, 0.0f),
vec3(0.0f, 1.0f, 0.0f));
(rightfully) prepares to step back back 2 units with the cam; but that matrix is not used in the shader
void main(){
gl_Position = projection * vec4(pos, 1.0f);
}
⊗ The shaders are first created and attached to the program, but on success deleted and detached again from the program which is intended to be used
glDetachShader(ProgramID, VertexShaderID);
glDetachShader(ProgramID, FragmentShaderID);
glDeleteShader(VertexShaderID);
glDeleteShader(FragmentShaderID);
⊗ These calls
glMatrixMode(GL_PROJECTION);
/* ... */
gluPerspective(75.0f, 16.0f / 9, 0.1f, 100.0f);
/* ... */
glMatrixMode(GL_MODELVIEW);
are meant for the (deprecated) fixed pipeline; which is not used here, and
⊗ there is no glClear() call in the code
There may be more things to attend to, but this is what I see on the first look.
We can have a deeper look into the code it if those things are dealt with first.

Answer 2

Solved!
The problem was that I wasn't using the program that holds the uniforms, so it failed to load them. Thanks to #BDL I started watching for OpenGL errors and i found GL_INVALID_OPERATION after every glUniformMatrix4fv. Poor debugging on my part. Thanks to everyone that helped
TL;DR put glUseProgram(program) before any glUniformMatrix4fv()