opengl crashes when trying to apply textures - opengl

Question

I'm trying to apply textures to opengl program, but the program just crashes for some reason, can someone tell me what I did wrong? Trying to fix this problem for two days now :/ works fine when color in fragment shader is set to some random color, but when color is:
vec4 textColor = texture(u_Texture, v_TextCoord);
color = textColor;
Edited:
#define GLEW_STATIC
#define alloca __builtin_alloca
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include <fstream>
#include <sstream>
#include <stb_image.h>
using namespace std;
static string ParseShader(const string& filepath);
static unsigned int CompileShader(unsigned int type, const string& source);
static unsigned int CreateShader(const string& vertexShader, const string& fragmentShader);
void glCheckError();
float vertex[] =
{
0.5f, 0.5f, 0.0f,
1.0f, 1.0f, // 0
0.5f, -0.5f, 0.0f,
1.0f, 0.0f, // 1
-0.5f, -0.5f, 0.0f,
0.0f, 0.0f, // 2
-0.5f, 0.5f, 0.0f,
0.0f, 1.0f // 3
};
float vertexBack[] =
{
-0.6, -0.6f, -0.5f, // 0
0.6f, -0.6f, -0.5f, // 1
0.6f, 0.6f, -0.5f, // 2
-0.6f, 0.6f, -0.5f // 3
};
unsigned int indexes[] =
{
0, 1, 3, // first triangle
1, 2, 3 // second triangle
};
int main(void)
{
GLFWwindow* window;
/* Initialize the library */
if (!glfwInit())
{
cout << "GLFW failed to load!" << endl;
return -1;
}
else
cout << "GLFW loaded" << endl << endl;
/* Create a windowed mode window and its OpenGL context */
window = glfwCreateWindow(800, 600, "Window", NULL, NULL);
if (!window)
{
glfwTerminate();
return -1;
}
/* Make the window's context current */
glfwMakeContextCurrent(window);
glewExperimental = GL_TRUE;
if(glewInit() != GLEW_OK)
cout << "Error loading GLEW" << endl;
else
cout << "GLEW loaded - version: " << glGetString(GL_VERSION) << endl;
unsigned int shader = CreateShader(ParseShader("shaders/vertex.shader"), ParseShader("shaders/fragment.shader"));
glUseProgram(shader);
// Make vertex position array
unsigned int buffers;
glGenBuffers(1, &buffers);
glBindBuffer(GL_ARRAY_BUFFER, buffers);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertex), vertex, GL_STATIC_DRAW);
// Make vertex position indexes out of arrays
unsigned int ib;
glGenBuffers(1, &ib);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ib);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indexes), indexes, GL_STATIC_DRAW);
// Position layout
unsigned int posAttrib = glGetAttribLocation(shader, "position");
glEnableVertexAttribArray(posAttrib);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(float) * 5, 0);
// Texture layout
unsigned int texAttrib = glGetAttribLocation(shader, "texCoord");
glEnableVertexAttribArray(texAttrib);
glCheckError();
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 5, (void*)(3 * sizeof(float)));
// Load image
int h, w, v_bpp;
unsigned char *image = stbi_load("texture.png", &w, &h, &v_bpp, 4);
if(image == nullptr)
cout << "failed to load image!" << endl;
unsigned int texture_id;
glGenTextures(1, &texture_id);
glBindTexture(GL_TEXTURE_2D, texture_id);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, image);
glGenerateMipmap(GL_TEXTURE_2D);
stbi_image_free(image);
// Set slot
glActiveTexture(GL_TEXTURE0);
int location = glGetUniformLocation(shader, "u_Texture");
glUniform1i(location, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glBindTexture(GL_TEXTURE_2D, 0);
/* Loop until the user closes the window */
while (!glfwWindowShouldClose(window) && glfwGetKey(window, GLFW_KEY_ESCAPE ) != GLFW_PRESS)
{
/* Render here */
glClear(GL_COLOR_BUFFER_BIT);
//glDrawArrays(GL_TRIANGLES, 0, 6);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr);
glCheckError();
/* Swap front and back buffers */
glfwSwapBuffers(window);
/* Poll for and process events */
glfwPollEvents();
}
glfwTerminate();
return 0;
}
static string ParseShader(const string& filepath) {
ifstream stream(filepath);
string line;
stringstream code;
while(getline(stream, line))
code << line << "\n";
return code.str();
}
static unsigned int CompileShader(unsigned int type, const string& source) {
unsigned int id = glCreateShader(type);
const char* src = source.c_str();
glShaderSource(id, 1, &src, NULL);
glCompileShader(id);
int result;
glGetShaderiv(id, GL_COMPILE_STATUS, &result);
if(result == GL_FALSE)
{
int length;
glGetShaderiv(id, GL_INFO_LOG_LENGTH, &length);
char* message = (char*)alloca(length * sizeof(char));
glGetShaderInfoLog(id, length, &length, message);
cout << "Failed to compile " << (type == GL_VERTEX_SHADER ? "Vertex" : "Fragment") << " shader!" << endl;
cout << message << endl;
glDeleteShader(id);
return 0;
}
return id;
}
static unsigned int CreateShader(const string& vertexShader, const string& fragmentShader) {
unsigned int program = glCreateProgram();
unsigned int vs = CompileShader(GL_VERTEX_SHADER, vertexShader);
unsigned int fs = CompileShader(GL_FRAGMENT_SHADER, fragmentShader);
glAttachShader(program, vs);
glAttachShader(program, fs);
glLinkProgram(program);
glValidateProgram(program);
glDeleteShader(vs);
glDeleteShader(fs);
return program;
}
void glCheckError() {
GLenum err = glGetError();
while(err!=GL_NO_ERROR) {
string error;
switch(err) {
case GL_INVALID_OPERATION: error="INVALID_OPERATION"; break;
case GL_INVALID_ENUM: error="INVALID_ENUM"; break;
case GL_INVALID_VALUE: error="INVALID_VALUE"; break;
case GL_OUT_OF_MEMORY: error="OUT_OF_MEMORY"; break;
case GL_INVALID_FRAMEBUFFER_OPERATION: error="INVALID_FRAMEBUFFER_OPERATION"; break;
}
cerr << err << " (" << error.c_str() << ")" <<endl;
err=glGetError();
}
}

Answer 1

You totally screwed up your vertex attribute ponter setup:
// Position layout
unsigned int posAttrib = glGetAttribLocation(shader, "position");
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(float) * 5, 0);
First, you query for an attribute named position, but you never use that index, you instead use 0.
// Texture layout
unsigned int texAttrib = glGetAttribLocation(shader, "texCoord");
glEnableVertexAttribArray(1);
glCheckError();
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 5, (void*)(3 * sizeof(float)));
Then, you query for texCoord, ignore it again, enable attribute array 1, and overwrite the attribute pointer for attribute 0.
THis means that attribute 1 has some undefined pointer value, and you have undefined behavior.
What most likely happens is that you are lucky when you not use the texture, because you only have one active attribute which happens to get location 0. And your GL implementation seems to ignore attribute arrays for non-active attributes, so it does not crash. When you have both attributes enables, chances are that they will be 0 and 1, and there is no way not to dereference that invalid pointer.