I am trying to display a texture, but for some reason it's not shown correctly it's distorted.
This is my source code:
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"
void processInput(GLFWwindow *window)
{
if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, true);
}
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
glViewport(0, 0, width, height);
}
int main(void)
{
int success;
char infoLog[512];
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
GLFWwindow* window = glfwCreateWindow(800, 600, "LearnOpenGL", NULL, NULL);
if (window == NULL)
{
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
std::cout << "Failed to initialize GLAD" << std::endl;
return -1;
}
glViewport(0, 0, 800, 600);
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
const char *vertexShaderSource = "#version 330 core\n"
"layout (location = 0) in vec3 aPos;\n"
"layout (location = 1) in vec2 aTexCoord;\n"
"out vec2 TexCoord;\n"
"void main()\n"
"{\n"
" gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
"TexCoord = aTexCoord;"
"}\0";
unsigned int vertexShader;
vertexShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
glCompileShader(vertexShader);
glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
if(!success)
{
glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
}
const char* fragmentShaderSource = "#version 330 core\n"
"out vec4 FragColor;\n"
"in vec2 TexCoord;\n"
"uniform sampler2D ourTexture;\n"
"void main()\n"
"{\n"
"FragColor = texture(ourTexture, TexCoord);\n"
"}\0";
unsigned int fragmentShader;
fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
glCompileShader(fragmentShader);
glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
if(!success)
{
glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
}
unsigned int shaderProgram;
shaderProgram = glCreateProgram();
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
glLinkProgram(shaderProgram);
glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
if(!success) {
glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
}
float vertices[] = {
//positions //texture coords
1.0f, 1.0f, 0.0f, 1.0f, 1.0f,// top right
1.0f, -1.0f, 0.0f, 1.0f, 0.0f,// bottom right
-1.0f, -1.0f, 0.0f, 0.0f, 0.0f,// bottom left
-1.0f, 1.0f, 0.0f, 0.0f, 1.0f// top left
};
unsigned int indices[] = {
0, 1, 3, // first triangle
1, 2, 3 // second triangle
};
unsigned int VBO;
unsigned int EBO;
unsigned int VAO;
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &EBO);
glGenBuffers(1, &VBO);
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
unsigned int texture;
glGenTextures(1, &texture);
//glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_TEXTURE_WRAP_S);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_TEXTURE_WRAP_T);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
int width, height, nrChannels;
stbi_set_flip_vertically_on_load(1);
unsigned char *data = stbi_load("../asd.jpg", &width, &height,&nrChannels, 0);
if (data)
{
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
if(stbi_failure_reason())
std::cout << stbi_failure_reason();
}
while(!glfwWindowShouldClose(window))
{
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
glBindTexture(GL_TEXTURE_2D, texture);
glUseProgram(shaderProgram);
glBindVertexArray(VAO);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
processInput(window);
glfwSwapBuffers(window);
glfwPollEvents();
}
glDeleteShader(vertexShader);
glDeleteShader(fragmentShader);
glfwTerminate();
return 0;
}
Expected result:
I checked all coordinates and positions and everything looks correct. I have no idea why the texture is not shown correctly. The vertex and fragment shaders also seems to be correct.
By default OpenGL assumes that the start of each row of an image is aligned to 4 bytes. This is because the GL_UNPACK_ALIGNMENT
parameter by default is 4. Since the image has 3 color channels (GL_RGB
), and is tightly packed the size of a row of the image may not be aligned to 4 bytes.
When a RGB image with 3 color channels is loaded to a texture object and 3*width is not divisible by 4, GL_UNPACK_ALIGNMENT
has to be set to 1, before specifying the texture image with glTexImage2D
:
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);