glDrawArrays doesn't work - c++

Question

I'm trying to draw a triangle using glDrawArrays function and gl Vertex, Color pointers.
The result is only black empty screen.
static const GLfloat vboData[] =
{ -0.5f, -0.5f, 0.0f,
0.0f, 0.5f, 0.0f,
0.5f, -0.5f, 0.0f,
};
static const GLfloat colors[]={
0.0f, 1.0f, 0.0f,
1.0f, 0.0f, 0.0f,
0.0f, 0.0f, 1.0f,
};
while(!glfwWindowShouldClose(window))
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);
glVertexPointer(3, GL_FLOAT, 0, vboData);
glColorPointer(3, GL_FLOAT, 0, colors);
glDrawArrays(GL_TRIANGLES, 0, 3);
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_COLOR_ARRAY);
glfwSwapBuffers(window);
glfwPollEvents();
}
Using VBO and VAO also doesn't work.
GLuint vao;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
static const GLfloat vboData[] =
{ -0.5f, -0.5f, 0.0f,
0.0f, 0.5f, 0.0f,
0.5f, -0.5f, 0.0f,
};
GLuint vbo;
glGenBuffers(1,&vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(vboData), vboData, GL_STATIC_DRAW);
while(!glfwWindowShouldClose(window))
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glBindVertexArray(vao);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
glDrawArrays(GL_TRIANGLES, 0, 3);
glDisableVertexAttribArray(0);
glfwSwapBuffers(window);
glfwPollEvents();
}

Answer 1

So, what I needed to get my code working is adding shaders to the project.
Here is minimal example.
This is my main.cpp
#include <iostream>
#include <fstream>
#include <algorithm>
#include "Loader.hpp"
#include <GL/glew.h>
#include <GLFW/glfw3.h>
GLFWwindow *window;
int main(void)
{
//Viewport,window setup using GLFW;
if(!glfwInit()){
return -1;
}
glfwWindowHint(GLFW_SAMPLES, 4);
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
window = glfwCreateWindow(640, 480, "OpenGL Triangle", NULL, NULL);
if(!window){
glfwTerminate();
exit(EXIT_FAILURE);
}
glfwMakeContextCurrent(window);
glewExperimental = true;
if (glewInit() != GLEW_OK) {
fprintf(stderr, "Failed to initialize GLEW\n");
getchar();
glfwTerminate();
return -1;
}
//Loading and compiling shaders;
GLuint shaderID = LoadShader("vertexs.shader", "fragments.shader");
GLuint vao;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
static const GLfloat vboData[] =
{ -1.0f, -1.0f, 0.0f,
1.0f, -1.0f, 0.0f,
1.0f, 1.0f, 0.0f,
};
GLuint vbo;
glGenBuffers(1,&vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(vboData), vboData, GL_STATIC_DRAW);
glUseProgram(shaderID); //Attaching shaders
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
while(!glfwWindowShouldClose(window))
{
glClear(GL_COLOR_BUFFER_BIT);
glBindVertexArray(vao);
glDrawArrays(GL_TRIANGLES, 0, 3);
glfwSwapBuffers(window);
glfwPollEvents();
}
glDeleteBuffers(1, &vbo);
glDeleteProgram(shaderID);
glDeleteVertexArrays(1, &vao);
glfwTerminate();
exit(EXIT_SUCCESS);
return 0;
}
Loader.hpp
#ifndef Loader_hpp
#define Loader_hpp
#include <stdio.h>
#include <string>
#include <vector>
#include <iostream>
#include <fstream>
#include <algorithm>
#include <GL/glew.h>
#include <GLFW/glfw3.h>
GLuint LoadShader(const char* vertex_file_path, const char* fragment_file_path);
#endif
Loader.cpp
#include "Loader.hpp"
GLuint LoadShader(const char * vertex_file_path,const char * fragment_file_path)
{
// 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, std::ios::in);
if(VertexShaderStream.is_open()){
std::string Line = "";
while(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();
return 0;
}
// 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(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);
glGetShaderiv(VertexShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
if ( InfoLogLength > 0 )
{
std::vector<char> VertexShaderErrorMessage(InfoLogLength+1);
glGetShaderInfoLog(VertexShaderID, InfoLogLength, NULL, &VertexShaderErrorMessage[0]);
printf("%s\n", &VertexShaderErrorMessage[0]);
}
// Compile Fragment Shader
printf("Compiling shader : %s\n", fragment_file_path);
char const * FragmentSourcePointer = FragmentShaderCode.c_str();
glShaderSource(FragmentShaderID, 1, &FragmentSourcePointer , NULL);
glCompileShader(FragmentShaderID);
// Check Fragment Shader
glGetShaderiv(FragmentShaderID, GL_COMPILE_STATUS, &Result);
glGetShaderiv(FragmentShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
if ( InfoLogLength > 0 )
{
std::vector<char> FragmentShaderErrorMessage(InfoLogLength+1);
glGetShaderInfoLog(FragmentShaderID, InfoLogLength, NULL, &FragmentShaderErrorMessage[0]);
printf("%s\n", &FragmentShaderErrorMessage[0]);
}
// 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);
glGetProgramiv(ProgramID, GL_INFO_LOG_LENGTH, &InfoLogLength);
if ( InfoLogLength > 0 )
{
std::vector<char> ProgramErrorMessage(InfoLogLength+1);
glGetProgramInfoLog(ProgramID, InfoLogLength, NULL, &ProgramErrorMessage[0]);
printf("%s\n", &ProgramErrorMessage[0]);
}
glDetachShader(ProgramID, VertexShaderID);
glDetachShader(ProgramID, FragmentShaderID);
glDeleteShader(VertexShaderID);
glDeleteShader(FragmentShaderID);
return ProgramID;
}
vertexs.shader (extension actually doesn't matter)
#version 330 core
layout(location = 0) in vec3 vertexPosition_modelspace;
void main()
{
//We're not modifying positions of vertices
gl_Position.xyz = vertexPosition_modelspace;
gl_Position.w = 1.0;
}
fragments.shader
#version 330 core
out vec3 color;
void main()
{
color = vec3(1,0,1);
}
I also found these tutorials extremely useful to make this solution, so the code above is partially taken from there.