So I have been trying to write a basic program that displays a quad on the screen. And no matter what I do it just shows a black screen. I checked the libraries, everything was linked. I checked the code, everything seemed fine (but I know that its not) but most absurdly: when I paste a what seems like the same program into the same project on the same computer it works, and when I paste the one again, it does not work, again.
By the way - I also tried running it through a text difference finder online... it showed that it was the same thing.
Original code (not working):
#include <iostream>
#include <fstream>
#include <string>
#include "GL/glew.h"
#include "GLFW/glfw3.h"
static unsigned int CompileShader(const std::string& source, unsigned int type) {
unsigned int shader = glCreateShader(type);
const char* src = source.c_str();
glShaderSource(shader, 1, &src, nullptr);
glCompileShader(shader);
int result;
glGetShaderiv(shader, GL_COMPILE_STATUS, &result);
// i - int
// v - vector
if (result == GL_FALSE) {
std::cout << "Shader cannot be compiled.\n" << (type == GL_VERTEX_SHADER ? "vertex s." : "fragments.") << "\n";
int length;
glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &length);
char* message = (char*)_malloca(length * sizeof(char));
glGetShaderInfoLog(shader, length, &length, message);
std::cout << message << "\n";
glDeleteShader(shader);
}
return shader;
}
static int CreateShader(const std::string& vShader, const std::string& fShader) {
unsigned int program = glCreateProgram();
unsigned int vs = CompileShader(vShader, GL_VERTEX_SHADER);
unsigned int fs = CompileShader(fShader, GL_FRAGMENT_SHADER);
glAttachShader(program, vs);
glAttachShader(program, fs);
glLinkProgram(program);
glValidateProgram(program);
glDeleteShader(vs);
glDeleteShader(fs);
return program;
}
int main() {
glfwInit();
GLFWwindow* window = glfwCreateWindow(1280, 720, "CITY ENGINE", 0, 0);
glfwMakeContextCurrent(window);
glewInit();
float vertices[8] = { 0.1f, 0.1f,
-0.1f, 0.1f,
-0.1f, -0.1f,
0.1f, -0.1f };
unsigned int varray;
glGenVertexArrays(1, &varray);
glBindVertexArray(varray);
unsigned int vbuffer;
glGenBuffers(1, &vbuffer);
glBindBuffer(vbuffer, GL_ARRAY_BUFFER);
glBufferData(GL_ARRAY_BUFFER, 4 * 2 * sizeof(float), vertices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, 0);
glEnableVertexAttribArray(0);
unsigned int indices[6] = { 0, 1, 2,
2, 3, 0 };
unsigned int ibuffer;
glGenBuffers(1, &ibuffer);
glBindBuffer(ibuffer, GL_ELEMENT_ARRAY_BUFFER);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, 6 * sizeof(unsigned int), indices, GL_STATIC_DRAW);
unsigned int shader = CreateShader(
"#version 330 core\n"
"\n"
"layout(location = 0) in vec4 position;\n"
"\n"
"void main()\n"
"{\n"
"gl_Position = position;\n"
"};\n"
,
"#version 330 core\n"
"\n"
"layout(location = 0) out vec4 color;\n"
"uniform vec4 u_Color;\n"
"\n"
"void main()\n"
"{\n"
" color = u_Color;\n"
"};\n"
);
glUseProgram(shader);
int location = glGetUniformLocation(shader, "u_Color");
glUniform4f(location, 0.3f, 0.3f, 1.0f, 1.0f);
glBindVertexArray(0);
glUseProgram(0);
glBindBuffer(0, GL_ARRAY_BUFFER);
glBindBuffer(0, GL_ELEMENT_ARRAY_BUFFER);
while (!glfwWindowShouldClose(window)) {
glClear(GL_COLOR_BUFFER_BIT);
glBindVertexArray(varray);
glBindBuffer(ibuffer, GL_ELEMENT_ARRAY_BUFFER);
glUseProgram(shader);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr);
glfwSwapBuffers(window);
glfwPollEvents();
}
}
The working one:
#include <iostream>
#include <fstream>
#include <string>
#include "GL/glew.h"
#include "GLFW/glfw3.h"
static unsigned int CompileShader(const std::string& source, unsigned int type) {
unsigned int shader = glCreateShader(type);
const char* src = source.c_str();
glShaderSource(shader, 1, &src, nullptr);
glCompileShader(shader);
int result;
glGetShaderiv(shader, GL_COMPILE_STATUS, &result);
// i - int
// v - vector
if (result == GL_FALSE) {
std::cout << "Shader cannot be compiled.\n" << (type == GL_VERTEX_SHADER ? "vertex s." : "fragments.") << "\n";
int length;
glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &length);
char* message = (char*)_malloca(length * sizeof(char));
glGetShaderInfoLog(shader, length, &length, message);
std::cout << message << "\n";
glDeleteShader(shader);
}
return shader;
}
static int CreateShader(const std::string& vShader, const std::string& fShader) {
unsigned int program = glCreateProgram();
unsigned int vs = CompileShader(vShader, GL_VERTEX_SHADER);
unsigned int fs = CompileShader(fShader, GL_FRAGMENT_SHADER);
glAttachShader(program, vs);
glAttachShader(program, fs);
glLinkProgram(program);
glValidateProgram(program);
glDeleteShader(vs);
glDeleteShader(fs);
return program;
}
int main() {
glfwInit();
GLFWwindow* window;
window = glfwCreateWindow(640, 480, "Modern OpenGL Test", NULL, NULL);
glfwMakeContextCurrent(window);
glewInit();
float vertices[] = {
-0.5f, -0.5f,
0.5f, -0.5f,
0.5f, 0.5f,
-0.5f, 0.5f,
};
unsigned int indices[] = {
0, 1, 2,
2, 3, 0
};
unsigned int varray;
glGenVertexArrays(1, &varray);
glBindVertexArray(varray);
unsigned int vb;
glGenBuffers(1, &vb);
glBindBuffer(GL_ARRAY_BUFFER, vb);
glBufferData(GL_ARRAY_BUFFER, 4 * 2 * sizeof(float), vertices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, 0);
glEnableVertexAttribArray(0);
unsigned int ib;
glGenBuffers(1, &ib);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ib);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, 6 * sizeof(unsigned int), indices, GL_STATIC_DRAW);
unsigned int shaders = CreateShader(
"#version 330 core\n"
"\n"
"layout(location = 0) in vec4 position;\n"
"\n"
"void main()\n"
"{\n"
" gl_Position = position;\n"
"};\n"
,
"#version 330 core\n"
"\n"
"layout(location = 0) out vec4 color;\n"
"\n"
"uniform vec4 u_Color;\n"
"\n"
"void main()\n"
"{\n"
" color = u_Color;\n"
"};\n");
glUseProgram(shaders);
int location = glGetUniformLocation(shaders, "u_Color");
glUniform4f(location, 0.3f, 0.3f, 1.0f, 1.0f);
glBindVertexArray(0);
glUseProgram(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
while (!glfwWindowShouldClose(window)) {
glClear(GL_COLOR_BUFFER_BIT);
glBindVertexArray(varray);
glUseProgram(shaders);
glBindBuffer(ib, GL_ELEMENT_ARRAY_BUFFER);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr);
glfwSwapBuffers(window);
glfwPollEvents();
}
glDeleteProgram(shaders);
glfwTerminate();
}
Notepad++ compare returns 2 significant differences between your files.
glBindBuffer(GL_ARRAY_BUFFER, vb); -> glBindBuffer(vbuffer, GL_ARRAY_BUFFER);glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ib); -> glBindBuffer(ibuffer, GL_ELEMENT_ARRAY_BUFFER);And quick look at docs.gl tells me that first argument should be target and not buffer