#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include <FreeImage.h>
using namespace std;
int framebufferWidth, framebufferHeight;
GLuint triangleVertexArrayObject;
GLuint triangleShaderProgramID;
GLuint trianglePositionVertexBufferObjectID, triangleColorVertexBufferObjectID;
GLuint triangleTextureCoordinateBufferObjectID;
//CreateTexture 함수의 원본 코드 출처
//https://r3dux.org/2014/10/how-to-load-an-opengl-texture-using-the-freeimage-library-or-freeimageplus-technically/
//
// Method to load an image into a texture using the freeimageplus library. Returns the texture ID or dies trying.
GLuint CreateTexture(char const* filename)
{
// Determine the format of the image.
// Note: The second paramter ('size') is currently unused, and we should use 0 for it.
FREE_IMAGE_FORMAT format = FreeImage_GetFileType(filename, 0);
// Image not found? Abort! Without this section we get a 0 by 0 image with 0 bits-per-pixel but we don't abort, which
// you might find preferable to dumping the user back to the desktop.
if (format == -1)
{
cout << "Could not find image: " << filename << " - Aborting." << endl;
exit(-1);
}
// Found image, but couldn't determine the file format? Try again...
if (format == FIF_UNKNOWN)
{
cout << "Couldn't determine file format - attempting to get from file extension..." << endl;
// ...by getting the filetype from the filename extension (i.e. .PNG, .GIF etc.)
// Note: This is slower and more error-prone that getting it from the file itself,
// also, we can't use the 'U' (unicode) variant of this method as that's Windows only.
format = FreeImage_GetFIFFromFilename(filename);
// Check that the plugin has reading capabilities for this format (if it's FIF_UNKNOWN,
// for example, then it won't have) - if we can't read the file, then we bail out =(
if (!FreeImage_FIFSupportsReading(format))
{
cout << "Detected image format cannot be read!" << endl;
exit(-1);
}
}
// If we're here we have a known image format, so load the image into a bitap
FIBITMAP* bitmap = FreeImage_Load(format, filename);
// How many bits-per-pixel is the source image?
int bitsPerPixel = FreeImage_GetBPP(bitmap);
// Convert our image up to 32 bits (8 bits per channel, Red/Green/Blue/Alpha) -
// but only if the image is not already 32 bits (i.e. 8 bits per channel).
// Note: ConvertTo32Bits returns a CLONE of the image data - so if we
// allocate this back to itself without using our bitmap32 intermediate
// we will LEAK the original bitmap data, and valgrind will show things like this:
//
// LEAK SUMMARY:
// definitely lost: 24 bytes in 2 blocks
// indirectly lost: 1,024,874 bytes in 14 blocks <--- Ouch.
//
// Using our intermediate and cleaning up the initial bitmap data we get:
//
// LEAK SUMMARY:
// definitely lost: 16 bytes in 1 blocks
// indirectly lost: 176 bytes in 4 blocks
//
// All above leaks (192 bytes) are caused by XGetDefault (in /usr/lib/libX11.so.6.3.0) - we have no control over this.
//
FIBITMAP* bitmap32;
if (bitsPerPixel == 32)
{
cout << "Source image has " << bitsPerPixel << " bits per pixel. Skipping conversion." << endl;
bitmap32 = bitmap;
}
else
{
cout << "Source image has " << bitsPerPixel << " bits per pixel. Converting to 32-bit colour." << endl;
bitmap32 = FreeImage_ConvertTo32Bits(bitmap);
}
// Some basic image info - strip it out if you don't care
int imageWidth = FreeImage_GetWidth(bitmap32);
int imageHeight = FreeImage_GetHeight(bitmap32);
cout << "Image: " << filename << " is size: " << imageWidth << "x" << imageHeight << "." << endl;
// Get a pointer to the texture data as an array of unsigned bytes.
// Note: At this point bitmap32 ALWAYS holds a 32-bit colour version of our image - so we get our data from that.
// Also, we don't need to delete or delete[] this textureData because it's not on the heap (so attempting to do
// so will cause a crash) - just let it go out of scope and the memory will be returned to the stack.
GLubyte* textureData = FreeImage_GetBits(bitmap32);
// Generate a texture ID and bind to it
GLuint tempTextureID;
glGenTextures(1, &tempTextureID);
glBindTexture(GL_TEXTURE_2D, tempTextureID);
// Construct the texture.
// Note: The 'Data format' is the format of the image data as provided by the image library. FreeImage decodes images into
// BGR/BGRA format, but we want to work with it in the more common RGBA format, so we specify the 'Internal format' as such.
glTexImage2D(GL_TEXTURE_2D, // Type of texture
0, // Mipmap level (0 being the top level i.e. full size)
GL_RGBA, // Internal format
imageWidth, // Width of the texture
imageHeight, // Height of the texture,
0, // Border in pixels
GL_BGRA, // Data format
GL_UNSIGNED_BYTE, // Type of texture data
textureData); // The image data to use for this texture
// Specify our minification and magnification filters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glBindTexture(GL_TEXTURE_2D, 0);
// Check for OpenGL texture creation errors
GLenum glError = glGetError();
if (glError)
{
cout << "There was an error loading the texture: " << filename << endl;
switch (glError)
{
case GL_INVALID_ENUM:
cout << "Invalid enum." << endl;
break;
case GL_INVALID_VALUE:
cout << "Invalid value." << endl;
break;
case GL_INVALID_OPERATION:
cout << "Invalid operation." << endl;
default:
cout << "Unrecognised GLenum." << endl;
break;
}
cout << "See https://www.opengl.org/sdk/docs/man/html/glTexImage2D.xhtml for further details." << endl;
}
// Unload the 32-bit colour bitmap
FreeImage_Unload(bitmap32);
// If we had to do a conversion to 32-bit colour, then unload the original
// non-32-bit-colour version of the image data too. Otherwise, bitmap32 and
// bitmap point at the same data, and that data's already been free'd, so
// don't attempt to free it again! (or we'll crash).
if (bitsPerPixel != 32)
{
FreeImage_Unload(bitmap);
}
// Finally, return the texture ID
return tempTextureID;
}
bool initShaderProgram() {
//#3
const GLchar* vertexShaderSource =
"#version 330 core\n"
"in vec3 positionAttribute;"
//"in vec3 colorAttribute;"
"in vec2 textureCoordinateAttribute;"
//"out vec3 passColorAttribute;"
"out vec2 passTextureCoordinateAttribute;"
"void main()"
"{"
"gl_Position = vec4(positionAttribute, 1.0);"
//"passColorAttribute = colorAttribute;"
"passTextureCoordinateAttribute = textureCoordinateAttribute;"
"}";
//#4
const GLchar* fragmentShaderSource =
"#version 330 core\n"
//"in vec3 passColorAttribute;"
"in vec2 passTextureCoordinateAttribute;"
"out vec4 fragmentColor;"
"uniform sampler2D tex;"
"void main()"
"{"
//컬러만 출력
//"fragmentColor = vec4(passColorAttribute, 1.0);"
//텍스처만 출력
"fragmentColor = texture(tex, passTextureCoordinateAttribute);"
//텍스처와 컬러 같이 출력
//"fragmentColor = texture(tex, passTextureCoordinateAttribute)*vec4(passColorAttribute, 1.0); "
"}";
GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
glCompileShader(vertexShader);
GLint result;
GLchar errorLog[512];
glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &result);
if (!result)
{
glGetShaderInfoLog(vertexShader, 512, NULL, errorLog);
cerr << "ERROR: vertex shader 컴파일 실패\n" << errorLog << endl;
glDeleteShader(vertexShader);
return false;
}
GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
glCompileShader(fragmentShader);
glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &result);
if (!result)
{
glGetShaderInfoLog(fragmentShader, 512, NULL, errorLog);
cerr << "ERROR: fragment shader 컴파일 실패\n" << errorLog << endl;
return false;
}
//#5
triangleShaderProgramID = glCreateProgram();
glAttachShader(triangleShaderProgramID, vertexShader);
glAttachShader(triangleShaderProgramID, fragmentShader);
glLinkProgram(triangleShaderProgramID);
glDeleteShader(vertexShader);
glDeleteShader(fragmentShader);
glGetProgramiv(triangleShaderProgramID, GL_LINK_STATUS, &result);
if (!result) {
glGetProgramInfoLog(triangleShaderProgramID, 512, NULL, errorLog);
cerr << "ERROR: shader program 연결 실패\n" << errorLog << endl;
return false;
}
return true;
}
bool defineVertexArrayObject() {
//#1
//삼각형을 구성하는 vertex 데이터 - position과 color
float position[] = {
0.0f, 0.5f, 0.0f, //vertex 1 위 중앙
0.5f, -0.5f, 0.0f, //vertex 2 오른쪽 아래
-0.5f, -0.5f, 0.0f //vertex 3 왼쪽 아래
};
float color[] = {
1.0f, 0.0f, 0.0f, //vertex 1 : RED (1,0,0)
0.0f, 1.0f, 0.0f, //vertex 2 : GREEN (0,1,0)
0.0f, 0.0f, 1.0f //vertex 3 : BLUE (0,0,1)
};
float textureCoordinate[] = {
0.5f, 1.0f, //vertex 1
1.0f, 0.0f, //vertex 2
0.0f, 0.0f //vertex 3
};
//#2
//Vertex Buffer Object(VBO)를 생성하여 vertex 데이터를 복사한다.
glGenBuffers(1, &trianglePositionVertexBufferObjectID);
glBindBuffer(GL_ARRAY_BUFFER, trianglePositionVertexBufferObjectID);
glBufferData(GL_ARRAY_BUFFER, sizeof(position), position, GL_STATIC_DRAW);
glGenBuffers(1, &triangleColorVertexBufferObjectID);
glBindBuffer(GL_ARRAY_BUFFER, triangleColorVertexBufferObjectID);
glBufferData(GL_ARRAY_BUFFER, sizeof(color), color, GL_STATIC_DRAW);
glGenBuffers(1, &triangleTextureCoordinateBufferObjectID);
glBindBuffer(GL_ARRAY_BUFFER, triangleTextureCoordinateBufferObjectID);
glBufferData(GL_ARRAY_BUFFER, sizeof(textureCoordinate), textureCoordinate, GL_STATIC_DRAW);
//#6
glGenVertexArrays(1, &triangleVertexArrayObject);
glBindVertexArray(triangleVertexArrayObject);
GLint positionAttribute = glGetAttribLocation(triangleShaderProgramID, "positionAttribute");
if (positionAttribute == -1) {
cerr << "position 속성 설정 실패" << endl;
return false;
}
glBindBuffer(GL_ARRAY_BUFFER, trianglePositionVertexBufferObjectID);
glVertexAttribPointer(positionAttribute, 3, GL_FLOAT, GL_FALSE, 0, 0);
glEnableVertexAttribArray(positionAttribute);
/*
GLint colorAttribute = glGetAttribLocation(triangleShaderProgramID, "colorAttribute");
if (colorAttribute == -1) {
cerr << "color 속성 설정 실패" << endl;
return false;
}
glBindBuffer(GL_ARRAY_BUFFER, triangleColorVertexBufferObjectID);
glVertexAttribPointer(colorAttribute, 3, GL_FLOAT, GL_FALSE, 0, 0);
glEnableVertexAttribArray(colorAttribute);
*/
GLint textureCoordinateAttribute = glGetAttribLocation(triangleShaderProgramID, "textureCoordinateAttribute");
if (textureCoordinateAttribute == -1) {
cerr << "Texture Coordinate 속성 설정 실패" << endl;
return false;
}
glBindBuffer(GL_ARRAY_BUFFER, triangleTextureCoordinateBufferObjectID);
glVertexAttribPointer(textureCoordinateAttribute, 2, GL_FLOAT, GL_FALSE, 0, 0);
glEnableVertexAttribArray(textureCoordinateAttribute);
glBindVertexArray(0);
return true;
}
void framebufferSizeCallback(GLFWwindow* window, int width, int height)
{
//처음 2개의 파라미터는 viewport rectangle의 왼쪽 아래 좌표
//다음 2개의 파라미터는 viewport의 너비와 높이이다.
//framebuffer의 width와 height를 가져와 glViewport에서 사용한다.
glViewport(0, 0, width, height);
framebufferWidth = width;
framebufferHeight = height;
}
void errorCallback(int errorCode, const char* errorDescription)
{
cerr << "Error: " << errorDescription << endl;
}
void keyCallback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
glfwSetWindowShouldClose(window, GLFW_TRUE);
}
int main()
{
glfwSetErrorCallback(errorCallback);
if (!glfwInit()) {
cerr << "Error: GLFW 초기화 실패" << endl;
std::exit(EXIT_FAILURE);
}
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
//glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
glfwWindowHint(GLFW_SAMPLES, 4);
GLFWwindow* window = glfwCreateWindow(
800,
600,
"OpenGL Example",
NULL, NULL);
if (!window) {
glfwTerminate();
std::exit(EXIT_FAILURE);
}
glfwMakeContextCurrent(window);
glfwSetKeyCallback(window, keyCallback);
glfwSetFramebufferSizeCallback(window, framebufferSizeCallback);
glewExperimental = GL_TRUE;
GLenum errorCode = glewInit();
if (GLEW_OK != errorCode) {
cerr << "Error: GLEW 초기화 실패 - " << glewGetErrorString(errorCode) << endl;
glfwTerminate();
std::exit(EXIT_FAILURE);
}
if (!GLEW_VERSION_3_3) {
cerr << "Error: OpenGL 3.3 API is not available." << endl;
glfwTerminate();
std::exit(EXIT_FAILURE);
}
cout << "OpenGL version: " << glGetString(GL_VERSION) << endl;
cout << "GLSL version: " << glGetString(GL_SHADING_LANGUAGE_VERSION) << endl;
cout << "Vendor: " << glGetString(GL_VENDOR) << endl;
cout << "Renderer: " << glGetString(GL_RENDERER) << endl;
if (!initShaderProgram()) {
cerr << "Error: Shader Program 생성 실패" << endl;
glfwTerminate();
std::exit(EXIT_FAILURE);
}
if (!defineVertexArrayObject()) {
cerr << "Error: Shader Program 생성 실패" << endl;
glfwTerminate();
std::exit(EXIT_FAILURE);
}
glfwSwapInterval(1);
double lastTime = glfwGetTime();
int numOfFrames = 0;
int count = 0;
glUseProgram(triangleShaderProgramID);
glBindVertexArray(triangleVertexArrayObject);
GLuint texureId = CreateTexture("number-board.jpg");
glUniform1i(glGetUniformLocation(triangleShaderProgramID, "tex"), 0);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texureId);
while (!glfwWindowShouldClose(window)) {
double currentTime = glfwGetTime();
numOfFrames++;
if (currentTime - lastTime >= 1.0) {
printf("%f ms/frame %d fps \n", 1000.0 / double(numOfFrames), numOfFrames);
numOfFrames = 0;
lastTime = currentTime;
}
glClearColor(0, 0, 0, 1);
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(GL_TRIANGLES, 0, 3);
count++;
glfwSwapBuffers(window);
glfwPollEvents();
}
glUseProgram(0);
glBindVertexArray(0);
glDeleteProgram(triangleShaderProgramID);
glDeleteBuffers(1, &trianglePositionVertexBufferObjectID);
glDeleteBuffers(1, &triangleColorVertexBufferObjectID);
glDeleteBuffers(1, &triangleTextureCoordinateBufferObjectID);
glDeleteVertexArrays(1, &triangleVertexArrayObject);
glfwTerminate();
std::exit(EXIT_SUCCESS);
} |
추천 감사합니다.