Question

我遇到了以下问题：

我有这个顶点着色器：

#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);
}

以下片段着色器：

#version 410 core

in vec3 color;

out vec4 frag_color;

void main()
{
    frag_color = vec4(color, 1.0);
}

我想将颜色矢量从顶点着色器传递到fragent着色器，但是，屏幕上没有显示任何内容。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）;有用。因此，在两个阶段之间传递价值的东西必定是错误的。

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 loaded\n";
    }

    return content;
}

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();
}

有谁看到我做错了什么？

提前致谢！

Answer 1

vertex_color与顶点着色器中的变量不匹配。

Answer 2

问题在于：

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

这两个调用都将属性位置作为第一个参数。虽然该位置的位置可能恰好为0，但这不能保证，您应该将相同的参数传递给这两个调用：

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

顶点着色器未将值传递给片段着色器

2 个答案: