c++ - 未声明的标识符 'gl_Position'

Question

我正在训练用 cpp 做 opengl 的东西，但是我的程序有一个错误:/(vertexShader)

这是顶点着色器的代码:

void main(void)
{
    gl_Position = gl_Vertex; 
}

这里有调用着色器的主cpp文件:

#include <GL/glew.h>
#include <GL/freeglut.h>
#include <stdio.h>

static char* readFile(const char* filename) {
    // Open the file
    FILE* fp = fopen(filename, "rb");
    // Move the file pointer to the end of the file and determing the length
    fseek(fp, 0, SEEK_END);
    long file_length = ftell(fp);
    fseek(fp, 0, SEEK_SET);
    char* contents = new char[file_length + 1];
    // zero out memory
    for (int i = 0; i < file_length + 1; i++) {
        contents[i] = 0;
    }
    // Here's the actual read
    fread(contents, 1, file_length, fp);
    // This is how you denote the end of a string in C
    contents[file_length + 1] = '\0';
    fclose(fp);
    return contents;
}

GLuint makeVertexShader(const char* shaderSource) {
    GLuint vertexShaderID = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShaderID, 1, (const GLchar**)&shaderSource, NULL);
    glCompileShader(vertexShaderID);
    return vertexShaderID;
}

GLuint makeFragmentShader(const char* shaderSource) {
    GLuint fragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShaderID, 1, (const GLchar**)&shaderSource, NULL);
    glCompileShader(fragmentShaderID);
    return fragmentShaderID;
}

GLuint makeShaderProgram(GLuint vertexShaderID, GLuint fragmentShaderID) {
    GLuint shaderID = glCreateProgram();
    glAttachShader(shaderID, vertexShaderID);
    glAttachShader(shaderID, fragmentShaderID);
    glLinkProgram(shaderID);
    return shaderID;
}

int main(int argc, char** argv) {
    // Standard stuff...
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGBA);
    glutInitWindowSize(800, 600);
    glutCreateWindow("Shaders");
    glewInit();

    char* fragmentShaderSourceCode = readFile("fragmentShader.txt");
    char* vertexShaderSourceCode = readFile("vertexShader.txt");
    GLuint vertShaderID = makeVertexShader(vertexShaderSourceCode);
    GLuint fragShaderID = makeFragmentShader(fragmentShaderSourceCode);
    GLuint shaderProgramID = makeShaderProgram(vertShaderID, fragShaderID);
    glUseProgram(shaderProgramID);
    printf("vertShaderID is %d\n", vertShaderID);
    printf("fragShaderID is %d\n", fragShaderID);
    printf("shaderProgramID is %d\n", shaderProgramID);
    glDeleteProgram(shaderProgramID);
    int temp;
    scanf("%d", &temp);
    return 0;
}

错误:顶点着色器中未声明的标识符“gl_Position”我正在使用 visual studio 2015、Windows 8、intel cpu、amd gpu。

Answer 1

这与我上周回答的问题 (GLSL Error #132 Syntax error: "gl_position" parse error) 非常相似，并且可能是相同的解决方案，重新声明应该预定义的内置函数:

out gl_PerVertex { vec4 gl_Position; };

在那种情况下(或在这种情况下)，不清楚为什么需要这样做。它应该只在某些情况下才需要，例如 GL_ARB_separate_shader_objects 的延期。但是，这可能是 AMD 驱动程序的问题，因为他们也有 AMD 显卡。