I'm using GLFW for window context creation.
I have a procs.hpp file that just loads the required opengl functions (like glCreateShader
, glCreateProgram
etc) using glxGetProcAddress
.
The program compiles successfully but there is no point on screen when I run it. Just pink background.
Can someone point out the mistake?
#include <GLFW/glfw3.h>
#include <iostream>
#include <GL/glx.h>
#include <stdio.h>
#include "procs.hpp"
constexpr const GLchar * vertex_shader_source =
R"(#version 450 core
void main(){
gl_Position = vec4(0.3, 0.3, 0.5, 1.0);
}
)";
int a= printf("%s",vertex_shader_source);
constexpr const GLchar * fragment_shader_source =
R"(#version 450 core
out vec4 out_color;
void main(){
out_color= vec4(1,0,0,1);
}
)";
int main()
{
GLFWwindow* window;
GLuint vertex_shader;
GLuint fragment_shader;
GLuint program;
GLuint vertex_array_object;
/* Initialize the library */
if (!glfwInit()){
std::cerr<<"Error initializing glfw";
return -1;
}
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
/* Create a windowed mode window and its OpenGL context */
window = glfwCreateWindow(1000, 800, "Hello World", NULL, NULL);
if (!window)
{
glfwTerminate();
return -1;
}
/* Make the window's context current */
glfwMakeContextCurrent(window);
vertex_shader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertex_shader, 1, &vertex_shader_source, nullptr);
glCompileShader(vertex_shader);
fragment_shader = glCreateShader(GL_FRAGMENT_SHADER) ;
glShaderSource(fragment_shader,1,&fragment_shader_source,nullptr);
glCompileShader(fragment_shader);
program = glCreateProgram();
glAttachShader(program,vertex_shader);
glAttachShader(program,fragment_shader);
glLinkProgram(program);
// Delete the shaders as the program has them now
glDeleteShader(vertex_shader);
glDeleteShader(fragment_shader);
glCreateVertexArrays(1, &vertex_array_object);
glBindVertexArray(vertex_array_object);
glClearColor(1,0,1,1);
glPointSize(10.0f);
/* Loop until the user closes the window */
while (!glfwWindowShouldClose(window))
{
/* Render here */
glClear(GL_COLOR_BUFFER_BIT);
glUseProgram(program);
glDrawArrays(GL_POINTS, 0, 1);
/* Swap front and back buffers */
glfwSwapBuffers(window);
/* Poll for and process events */
glfwPollEvents();
}
glDeleteProgram(program);
glfwTerminate();
return 0;
}
The point size ( glPointSize
) of 10.0 is not guaranteed to be provided by the OpenGL Context .
Get the point size range by retrieving the parameter GL_POINT_SIZE_RANGE
:
GLfloat pointSizeRange[2];
glGetFloatv(GL_POINT_SIZE_RANGE, pointSizeRange);
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