顶点着色器没有向片段着色器传递值

Vertex shader not passing value to fragment shader

本文关键字：片段 顶点      更新时间：2023-10-16

我遇到了以下问题:

我得到这个顶点着色器:

#version 410 core
in vec3 vertex_position;
out vec3 color;
void main()
{
    color = vec3(0.0, 0.0, 0.0);
    gl_Position = vec4(vertex_position, 1.0);
}

和下面的片段着色器:

#version 410 core
in vec3 color;
out vec4 frag_color;
void main()
{
    frag_color = vec4(color, 1.0);
}

我想把颜色矢量从顶点着色器传递到分形着色器，然而，屏幕上什么也没有显示。当我在片段着色器中设置frag_color时:frag_color = vec4(0.0, 0.0, 0.0, 1.0);它的工作原理。因此，在两个阶段之间传递值一定是错误的。

这是我的着色器代码: 
void Shader::CreateShaders(std::string filePathVert, std::string filePathFrag)
{
    // setup shaders
    std::string vertex_shader_source   = LoadSourceFile(filePathVert);
    std::string fragment_shader_source = LoadSourceFile(filePathFrag);
    const GLchar* vs_source = vertex_shader_source.c_str();
    const GLchar* fs_source = fragment_shader_source.c_str();
    GLuint vs = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vs, 1, &vs_source, NULL);
    glCompileShader(vs);
    CheckShaderError(vs, GL_COMPILE_STATUS, false, "Error: Shader compilation failed: ");
    GLuint fs = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fs, 1, &fs_source, NULL);
    glCompileShader(fs);
    CheckShaderError(fs, GL_COMPILE_STATUS, false, "Error: Shader compilation failed: ");
    this->shader_program = glCreateProgram();
    glAttachShader(this->shader_program, fs);
    glAttachShader(this->shader_program, vs);
    glLinkProgram(this->shader_program);
    CheckValidationError(this->shader_program);
    glDeleteShader(vs);
    glDeleteShader(fs);
}
void Shader::Bind()
{
    glUseProgram(this->shader_program);
}
void Shader::Destroy()
{
    glDeleteProgram(this->shader_program);
}
static std::string LoadSourceFile(std::string filePath)
{
    std::ifstream ifs(filePath);
    std::string content( (std::istreambuf_iterator<char>(ifs) ),
                        (std::istreambuf_iterator<char>()    ) );
    if(content.empty())
    {
        std::cerr << "source file was empty or not correctly loadedn";
    }
    return content;
}

和我的绘图代码:

GLuint vao = 0;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, vbo_positions);
glVertexAttribPointer(glGetAttribLocation(shader.GetProgramID(), "vertex_position"), 3, GL_FLOAT, GL_FALSE, 0, NULL);
glBindBuffer(GL_ARRAY_BUFFER, vbo_colors);
glVertexAttribPointer(glGetAttribLocation(shader.GetProgramID(), "vertex_color"), 3, GL_FLOAT, GL_FALSE, 0, NULL);

while(!glfwWindowShouldClose(display.GetWindowID())) {
    display.UpdateFPSCounter();
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    shader.Bind();
    glBindVertexArray(vao);
    glDrawArrays(GL_TRIANGLES, 0, 3);
    update();
    glfwSwapBuffers(display.GetWindowID());
    display.CheckWindowShouldClose();
}

有人看到我做错了什么吗?

提前感谢!

vertex_color不匹配顶点着色器中的变量

问题就在这里:

glEnableVertexAttribArray(0);
glVertexAttribPointer(glGetAttribLocation(shader.GetProgramID(), "vertex_position"),
                      3, GL_FLOAT, GL_FALSE, 0, NULL);

这两个调用都将属性location作为第一个参数。虽然位置的位置可能恰好是0，但这并不能保证，您应该向这两个调用传递相同的参数:

GLuint posLoc = glGetAttribLocation(shader.GetProgramID(), "vertex_position");
glEnableVertexAttribArray(posLoc);
glVertexAttribPointer(posLoc, 3, GL_FLOAT, GL_FALSE, 0, NULL);
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