Dzień dobry, uczę się podstaw OpenGL.
Znalazłem taki kod w internecie, żeby utworzyć kolorową kostkę 3D.
Przykład był pisany przy pomocy biblioteki GLFW ja używam SDL2.
Przykład
A to jest mój przepisany kod w SDL2.
#include <iostream>
#include <SDL2/SDL.h>
#include <GL/glew.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
SDL_Window* window;
SDL_GLContext context;
const char* vertexShaderSrc =
"#version 330 core"
""
"// Input vertex data, different for all executions of this shader."
"layout(location = 0) in vec3 vertexPosition_modelspace;"
"layout(location = 1) in vec3 vertexColor;"
""
"// Output data ; will be interpolated for each fragment."
"out vec3 fragmentColor;"
"// Values that stay constant for the whole mesh."
"uniform mat4 MVP;"
""
"void main(){ "
""
" // Output position of the vertex, in clip space : MVP * position"
" gl_Position = MVP * vec4(vertexPosition_modelspace,1);"
""
" // The color of each vertex will be interpolated"
" // to produce the color of each fragment"
" fragmentColor = vertexColor;"
"}";
const char*fragmentShaderSrc =
"#version 330 core"
""
"// Interpolated values from the vertex shaders"
"in vec3 fragmentColor;"
""
"// Ouput data"
"out vec3 color;"
""
"void main(){"
""
" // Output color = color specified in the vertex shader, "
" // interpolated between all 3 surrounding vertices"
" color = fragmentColor;"
""
"}";
GLuint CompileShader(const char* src,GLenum shaderType){
GLuint shader = glCreateShader(shaderType);
glShaderSource(shader,1,&src,NULL);
glCompileShader(shader);
return shader;
}
int main()
{
SDL_Init(SDL_INIT_EVERYTHING);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
window = SDL_CreateWindow("OpenGLv4",SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED,
800,600,SDL_WINDOW_OPENGL|SDL_WINDOW_SHOWN);
context = SDL_GL_CreateContext(window);
glewExperimental = true;
if (glewInit() != GLEW_OK) {
fprintf(stderr, "Failed to initialize GLEW\n");
getchar();
SDL_GL_DeleteContext(context);
SDL_DestroyWindow(window);
SDL_Quit();
return -1;
}
glClearColor(0.0f, 0.0f, 0.4f, 1.0f);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LESS);
GLuint VertexArrayID;
glGenVertexArrays(1, &VertexArrayID);
glBindVertexArray(VertexArrayID);
GLuint shaderVert = CompileShader(vertexShaderSrc,GL_VERTEX_SHADER);
GLuint shaderFrag = CompileShader(fragmentShaderSrc,GL_FRAGMENT_SHADER);
GLuint shaderProg = glCreateProgram();
glAttachShader(shaderProg,shaderVert);
glAttachShader(shaderProg,shaderFrag);
glLinkProgram(shaderProg);
glDeleteShader(shaderFrag);
glDeleteShader(shaderVert);
GLuint MatrixID = glGetUniformLocation(shaderProg, "MVP");
glm::mat4 Projection = glm::perspective(glm::radians(45.0f), 4.0f / 3.0f, 0.1f, 100.0f);
glm::mat4 View = glm::lookAt(
glm::vec3(4,3,-3), // Camera is at (4,3,-3), in World Space
glm::vec3(0,0,0), // and looks at the origin
glm::vec3(0,1,0) // Head is up (set to 0,-1,0 to look upside-down)
);
glm::mat4 Model = glm::mat4(1.0f);
glm::mat4 MVP = Projection * View * Model;
static const GLfloat g_vertex_buffer_data[] = {
-1.0f,-1.0f,-1.0f,
-1.0f,-1.0f, 1.0f,
-1.0f, 1.0f, 1.0f,
1.0f, 1.0f,-1.0f,
-1.0f,-1.0f,-1.0f,
-1.0f, 1.0f,-1.0f,
1.0f,-1.0f, 1.0f,
-1.0f,-1.0f,-1.0f,
1.0f,-1.0f,-1.0f,
1.0f, 1.0f,-1.0f,
1.0f,-1.0f,-1.0f,
-1.0f,-1.0f,-1.0f,
-1.0f,-1.0f,-1.0f,
-1.0f, 1.0f, 1.0f,
-1.0f, 1.0f,-1.0f,
1.0f,-1.0f, 1.0f,
-1.0f,-1.0f, 1.0f,
-1.0f,-1.0f,-1.0f,
-1.0f, 1.0f, 1.0f,
-1.0f,-1.0f, 1.0f,
1.0f,-1.0f, 1.0f,
1.0f, 1.0f, 1.0f,
1.0f,-1.0f,-1.0f,
1.0f, 1.0f,-1.0f,
1.0f,-1.0f,-1.0f,
1.0f, 1.0f, 1.0f,
1.0f,-1.0f, 1.0f,
1.0f, 1.0f, 1.0f,
1.0f, 1.0f,-1.0f,
-1.0f, 1.0f,-1.0f,
1.0f, 1.0f, 1.0f,
-1.0f, 1.0f,-1.0f,
-1.0f, 1.0f, 1.0f,
1.0f, 1.0f, 1.0f,
-1.0f, 1.0f, 1.0f,
1.0f,-1.0f, 1.0f
};
static const GLfloat g_color_buffer_data[] = {
0.583f, 0.771f, 0.014f,
0.609f, 0.115f, 0.436f,
0.327f, 0.483f, 0.844f,
0.822f, 0.569f, 0.201f,
0.435f, 0.602f, 0.223f,
0.310f, 0.747f, 0.185f,
0.597f, 0.770f, 0.761f,
0.559f, 0.436f, 0.730f,
0.359f, 0.583f, 0.152f,
0.483f, 0.596f, 0.789f,
0.559f, 0.861f, 0.639f,
0.195f, 0.548f, 0.859f,
0.014f, 0.184f, 0.576f,
0.771f, 0.328f, 0.970f,
0.406f, 0.615f, 0.116f,
0.676f, 0.977f, 0.133f,
0.971f, 0.572f, 0.833f,
0.140f, 0.616f, 0.489f,
0.997f, 0.513f, 0.064f,
0.945f, 0.719f, 0.592f,
0.543f, 0.021f, 0.978f,
0.279f, 0.317f, 0.505f,
0.167f, 0.620f, 0.077f,
0.347f, 0.857f, 0.137f,
0.055f, 0.953f, 0.042f,
0.714f, 0.505f, 0.345f,
0.783f, 0.290f, 0.734f,
0.722f, 0.645f, 0.174f,
0.302f, 0.455f, 0.848f,
0.225f, 0.587f, 0.040f,
0.517f, 0.713f, 0.338f,
0.053f, 0.959f, 0.120f,
0.393f, 0.621f, 0.362f,
0.673f, 0.211f, 0.457f,
0.820f, 0.883f, 0.371f,
0.982f, 0.099f, 0.879f
};
GLuint vertexbuffer;
glGenBuffers(1, &vertexbuffer);
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_buffer_data, GL_STATIC_DRAW);
GLuint colorbuffer;
glGenBuffers(1, &colorbuffer);
glBindBuffer(GL_ARRAY_BUFFER, colorbuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(g_color_buffer_data), g_color_buffer_data, GL_STATIC_DRAW);
bool notClosed = true;
SDL_Event e;
while(notClosed){
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glUseProgram(shaderProg);
glUniformMatrix4fv(MatrixID, 1, GL_FALSE, &MVP[0][0]);
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
glVertexAttribPointer(
0, // attribute. No particular reason for 0, but must match the layout in the shader.
3, // size
GL_FLOAT, // type
GL_FALSE, // normalized?
0, // stride
(void*)0 // array buffer offset
);
glEnableVertexAttribArray(1);
glBindBuffer(GL_ARRAY_BUFFER, colorbuffer);
glVertexAttribPointer(
1, // attribute. No particular reason for 1, but must match the layout in the shader.
3, // size
GL_FLOAT, // type
GL_FALSE, // normalized?
0, // stride
(void*)0 // array buffer offset
);
glDrawArrays(GL_TRIANGLES, 0, 12*3); // 12*3 indices starting at 0 -> 12 triangles
glDisableVertexAttribArray(0);
glDisableVertexAttribArray(1);
SDL_GL_SwapWindow(window);
while(SDL_PollEvent(&e)){
if(e.type == SDL_QUIT){
notClosed = false;
}
}
}
glDeleteBuffers(1, &vertexbuffer);
glDeleteBuffers(1, &colorbuffer);
glDeleteVertexArrays(1, &VertexArrayID);
glDeleteProgram(shaderProg);
SDL_GL_DeleteContext(context);
SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}
Po uruchomieniu pojawia się tylko niebieskie okno.
