Question

使用一个程序和一组顶点/片段着色器后，我需要使用更多程序，因此我的初始设置函数不再具有任何参数了。

在我的设置功能中，我传递了shader_program和两个着色器源。当我尝试在我的显示方法中使用该程序时，GLuint程序句柄为零。我目前不明白的是为什么当我使用固定源为我的着色器时这一切都有效。它可能是一个C ++程序，我以错误的方式传递参数？我没有收到任何错误消息，但屏幕上没有任何内容。

这是我用来调用着色器设置功能和函数本身的代码：

// Variables
GLuint shader_program;

const GLchar *vertex_shader =   
"#version 330\n"
""
"layout (location = 0) in vec3 in_position;"
...
"";

// In my main function, I call this to set up the shaders
installShaders(shader_program, vertex_shader, fragment_shader);

// SET-UP-METHOD
void installShaders(GLuint program_handle, const GLchar *vertex_shader_source, const GLchar *fragment_shader_source)
{
// Handles for the shader objects
GLuint   vertex_shader_name;
GLuint fragment_shader_name;

// Status values 
GLint   vertex_shader_compiled;
GLint fragment_shader_compiled;
GLint      successfully_linked;

// Generate shader names
vertex_shader_name   = glCreateShader(GL_VERTEX_SHADER);
fragment_shader_name = glCreateShader(GL_FRAGMENT_SHADER);

// Specify the sources for the shaders
glShaderSource(  vertex_shader_name, 1, (const GLchar**)&vertex_shader_source  , NULL);
glShaderSource(fragment_shader_name, 1, (const GLchar**)&fragment_shader_source, NULL);

// Compile Vertex shader and check for errors
glCompileShader(vertex_shader_name);
glGetShaderiv(vertex_shader_name, GL_COMPILE_STATUS, &vertex_shader_compiled);
printShaderInfoLog(vertex_shader_name);

// Compile Fragment shader and check for errors
glCompileShader(fragment_shader_name);
glGetShaderiv(fragment_shader_name, GL_COMPILE_STATUS, &fragment_shader_compiled);
printShaderInfoLog(fragment_shader_name);

// Exit if the shaders couldn't be compiled correctly
if(!vertex_shader_compiled || !fragment_shader_compiled)
{
    printf("Shaders were not compiled correctly!\n");
    exit(EXIT_FAILURE);
}

// Generate program name
program_handle = glCreateProgram();

// Attach shaders to the program
glAttachShader(program_handle, vertex_shader_name);
glAttachShader(program_handle, fragment_shader_name);

// Link program and check for errors
glLinkProgram(program_handle);
glGetProgramiv(program_handle, GL_LINK_STATUS, &successfully_linked);
printProgramInfoLog(program_handle);

// Exit if the program couldn't be linked correctly
if(!successfully_linked)
{
    printf("Program was not linked correctly!\n");
    exit(EXIT_FAILURE);
}

// Set up initial values of uniform variables
glUseProgram(program_handle);

location_projectionMatrix = glGetUniformLocation(program_handle, "myProjectionMatrix");
printf("Location of the uniform -->myProjectionMatrix<--- : %i\n", location_projectionMatrix);
projectionMatrix = glm::mat4(1.0f);
glUniformMatrix4fv(location_projectionMatrix, 1, GL_FALSE, glm::value_ptr(projectionMatrix));

location_modelViewMatrix = glGetUniformLocation(program_handle, "myModelViewMatrix");
printf("Location of the uniform -->myModelViewMatrix<--- : %i\n", location_modelViewMatrix);
modelViewMatrix = glm::mat4(1.0f);
glUniformMatrix4fv(location_modelViewMatrix, 1, GL_FALSE, glm::value_ptr(modelViewMatrix));

glUseProgram(0);

// Everything worked
printf("Shaders were set up correctly!\n");
}

Answer 1

问题是存储GLSL着色器程序名称（从glCreateShader返回的值）的变量是按值传递到例程中的。因此，当函数返回时，其值将丢失。通过引用传递值（作为指针或C ++引用），然后在函数退出时保留该值，并且您将能够在应用程序的其他部分引用着色器。

设置OpenGL程序和着色器

1 个答案: