InitShader.cpp

#include "Angel-yjc.hpp"
using namespace std;

namespace Angel {

    // Create a NULL-terminated string by reading the provided file
    static char* readShaderSource(const char* shaderFile) {
        FILE* fp = fopen(shaderFile, "r");

        if (fp == NULL) {
            return NULL;
        }

        fseek(fp, 0L, SEEK_END);
        long size = ftell(fp);

        fseek(fp, 0L, SEEK_SET);
        char* buf = new char[size + 1];
        fread(buf, 1, size, fp);

        buf[size] = '\0';
        fclose(fp);

        // In case there are illegal non-ASCII characters (due to different
        // encoding systems), the following code will replace each of them
        // with a space ' '.
        for (int i = 0; i < size + 1; i++) {
            if (!(buf[i] >= 0 && buf[i] < 128)) buf[i] = ' ';
        }

        return buf;
    }

    // Create a GLSL program object from vertex and fragment shader files
    GLuint InitShader(const char* vShaderFile, const char* fShaderFile) {
        struct Shader {
            const char* filename;
            GLenum type;
            GLchar* source;
        } shaders[2] = {{vShaderFile, GL_VERTEX_SHADER, NULL},
                        {fShaderFile, GL_FRAGMENT_SHADER, NULL}};

        GLuint program = glCreateProgram();

        for (int i = 0; i < 2; ++i) {
            Shader& s = shaders[i];
            s.source = readShaderSource(s.filename);
            if (shaders[i].source == NULL) {
                cerr << "Failed to read " << s.filename << endl;
                exit(EXIT_FAILURE);
            } else
                cout << "Successfully read " << s.filename << endl;

            GLuint shader = glCreateShader(s.type);
            glShaderSource(shader, 1, (const GLchar**)&s.source, NULL);
            glCompileShader(shader);

            GLint compiled;
            glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
            if (!compiled) {
                cerr << s.filename << " failed to compile:" << endl;
                GLint logSize;
                glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &logSize);
                char* logMsg = new char[logSize];
                glGetShaderInfoLog(shader, logSize, NULL, logMsg);
                cerr << logMsg << endl;
                delete[] logMsg;

                exit(EXIT_FAILURE);
            } else
                cout << "Successfully compiled " << s.filename << endl;

            delete[] s.source;

            glAttachShader(program, shader);
        }

        /* link and error check */
        glLinkProgram(program);

        GLint linked;
        glGetProgramiv(program, GL_LINK_STATUS, &linked);
        if (!linked) {
            cerr << "Shader program failed to link" << endl;
            GLint logSize;
            glGetProgramiv(program, GL_INFO_LOG_LENGTH, &logSize);
            char* logMsg = new char[logSize];
            glGetProgramInfoLog(program, logSize, NULL, logMsg);
            cerr << logMsg << endl;
            delete[] logMsg;

            exit(EXIT_FAILURE);
        } else
            cout << "Successfully linked program object" << endl << endl;

        return program;
    }

}  // namespace Angel