Opengl着色器vec3未更新

Question

我试图更新三角形的每个frame.I颜色没有运气，我不明白为什么有人可以帮助我。我已经尝试了多次，改变我尝试的方式每次更新数据。任何帮助，将不胜感激。

#include <glew.h> 
#include <glfw3.h> 
#include <iostream> 
#include <fstream> 
#include <time.h> 
using namespace std; 

GLuint compileshaders() { 
    GLuint vshader, fshader, program; 

    static const GLchar * vshadersource[] = { 
     "#version 450 core    \n" 
     " layout (location=0) in vec3 position;\n" 
     " layout (location=1) in vec3 color;\n" 
     " out vec3 color_out    ;\n" 
     "void main()     \n" 
     "{        \n" 
     "color_out = color;    \n" 
     "gl_Position = vec4(position,1.0);\n" 
     "}        \n" 
    }; 

    static const GLchar * fshadersource[] = { 
     "#version 450 core    \n" 
     "in vec3 color_out;    \n" 
     "out vec4 colorO;     \n" 
     "void main()      \n" 
     "{        \n" 
     " colorO = vec4(color_out,1.0); \n" 
     "}        \n" 
    }; 

    vshader = glCreateShader(GL_VERTEX_SHADER); 
    glShaderSource(vshader, 1, vshadersource, NULL); 
    glCompileShader(vshader); 

    fshader = glCreateShader(GL_FRAGMENT_SHADER); 
    glShaderSource(fshader, 1, fshadersource, NULL); 
    glCompileShader(fshader); 

    GLint vCompiled = 0; 
    glGetShaderiv(vshader, GL_COMPILE_STATUS, &vCompiled); 
    GLint fCompiled = 0; 
    glGetShaderiv(fshader, GL_COMPILE_STATUS, &fCompiled); 

    if (vCompiled && fCompiled != GL_FALSE) { 
     program = glCreateProgram(); 
     glAttachShader(program, vshader); 
     glAttachShader(program, fshader); 
     glLinkProgram(program); 
     glDeleteShader(vshader); 
     glDeleteShader(fshader); 
     return program; 
    } 
    else { 
     cout << "Shader Error!" << endl; 
    } 

    glDeleteShader(vshader); 
    glDeleteShader(fshader); 

    return NULL; 
} 

int main(void) 
{ 
    srand(time(0)); 
    GLFWwindow* window; 
    GLuint program; 
    GLuint vertex_array_object; 
    GLuint buffers[2]; 

    if (!glfwInit()) 
     return -1; 

    window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL); 
    if (!window) 
    { 
     glfwTerminate(); 
     return -1; 
    } 

    glfwMakeContextCurrent(window); 

    glewInit(); 

    static const GLfloat positions[] = {0.25,-0.25,0.5,0.25,0.25,0.5,-0.25,-0.25,0.5}; 
    static GLfloat color[] = {1.0,0.0,0.0,0.0,1.0,0.0,0.0,0.0,1.0}; 

    program = compileshaders(); 
    glUseProgram(program); 
    glCreateVertexArrays(1, &vertex_array_object); 
    glCreateBuffers(2, &buffers[0]); 
    glNamedBufferStorage(buffers[0], sizeof(positions), positions, 0); 
    glVertexArrayVertexBuffer(vertex_array_object, 0, buffers[0], 0, sizeof(GLfloat) * 3); 
    glVertexArrayAttribFormat(vertex_array_object, 0, 3, GL_FLOAT, GL_FALSE, 0); 
    glVertexArrayAttribBinding(vertex_array_object, 0, 0); 
    glEnableVertexArrayAttrib(vertex_array_object, 0); 
    glNamedBufferStorage(buffers[1], sizeof(color), color, 0); 
    glVertexArrayVertexBuffer(vertex_array_object, 1, buffers[1], 0, sizeof(GLfloat) * 3); 
    glVertexArrayAttribFormat(vertex_array_object, 1, 3, GL_FLOAT, GL_FALSE, 0); 
    glVertexArrayAttribBinding(vertex_array_object, 1, 1); 
    glEnableVertexArrayAttrib(vertex_array_object, 1); 
    glBindVertexArray(vertex_array_object); 

    GLfloat clearcolor[4] = { 0.0,0.0,0.0,1.0 }; 
    glPointSize(40); 

    int width, height; 
    while (!glfwWindowShouldClose(window)) 
    { 
     glfwGetWindowSize(window, &width, &height); 
     glViewport(0, 0, width, height); 
     glClearBufferfv(GL_COLOR, 0, clearcolor); 

     for (int i = 0; i < 9; i++) { 
      color[i] = (rand() % 2); 
     } 
     glVertexAttrib3fv(1, color); 

     glDrawArrays(GL_TRIANGLES, 0, 3); 

     glfwSwapBuffers(window); 
     glfwPollEvents(); 
    } 

    glDeleteVertexArrays(1,&vertex_array_object); 
    glDeleteProgram(program); 

    glfwTerminate(); 
    return 0; 
} 

Answer 1

glNamedBufferStorage(buffers[1], sizeof(color), color, 0); 

这告诉OpenGL复制当前存储给定阵列中的在给定的buffer object数据。它不会在color和存储的缓冲区数据之间创建一些链接。处理此命令后，OpenGL无法知道您正在修改color。

而glVertexAttrib3fv没有做你认为的事情。

如果要更改OpenGL缓冲区对象中的数据，则必须进行OpenGL调用以将不同的数据上载到缓冲区中。

此外，您创建了一个静态缓冲区（使用参数为0）。静态缓冲区的全部要点是它的静态：其内容在创建时刻是固定的。因此，任何上传命令，如glNamedBufferSubData都不起作用。

因此，您需要决定如何更新缓冲区的数据。你想映射它并通过指针更改数据吗？你想持久地图吗？你想用glNamedBufferSubData来更新吗？在更新缓冲区之前是否要使缓冲区无效？有许多更新OpenGL缓冲区对象的策略。

最简单的一个将是无效的，并使用glNamedBufferSubData，但你需要的是一个适当的使用参数：

glNamedBufferStorage(buffers[1], sizeof(color), color, GL_DYNAMIC_STORAGE_BIT); 

...

while (!glfwWindowShouldClose(window)) 
{ 
    glfwGetWindowSize(window, &width, &height); 
    glViewport(0, 0, width, height); 
    glClearBufferfv(GL_COLOR, 0, clearcolor); 

    for (int i = 0; i < 9; i++) { 
     color[i] = (rand() % 2); 
    } 

    glInvalidateBufferData(buffer[1]); 
    glNamedBufferSubData(buffer[1], 0, sizeof(color), color); 

    glDrawArrays(GL_TRIANGLES, 0, 3); 

    glfwSwapBuffers(window); 
    glfwPollEvents(); 
}