Блог

Я экспериментирую с вычислительными шейдерами. Что я хочу сделать, так это отправить данные arr1 для вычисления переменной шейдера shader_arr1 [], сделать все ее элементы 1 и прочитать этот результат обратно на сторону процессора в переменной arr2 []. Однако, запустив следующую программу, я получаю то же начальное значение arr1[]{1,2,3,4,5,6,7} в arr2 [], ничего не изменилось. Не могли бы вы сказать мне, какую часть я делаю неправильно?

         GLuint program = glCreateProgram();
        GLuint computeShader = glCreateShader(GL_COMPUTE_SHADER);

        const GLchar* const shaderSrc = {
            "#version 310 esn"
            "n"
            "layout (local_size_x = 1) in;n"
            "layout(std430, binding = 0) writeonly buffer SSBO {n"
            "   int shader_arr1[];n"
            "};n"
            "void main(void)n"
            "{n"
            "   shader_arr1[gl_GlobalInvocationID.x] = 1;n"
            "}n"
        };

        glShaderSource(computeShader, 1, amp;shaderSrc, NULL);
        glCompileShader(computeShader);
        int resu<
        glGetShaderiv(computeShader, GL_COMPILE_STATUS, amp;result);

        if(result == GL_FALSE){
            int length;
            glGetShaderiv(computeShader, GL_INFO_LOG_LENGTH, amp;length);
            char* message = static_cast<char*>(malloc(length));
            glGetShaderInfoLog(computeShader, length, amp;length, message);
            __android_log_print(ANDROID_LOG_INFO, "MyLog", "Shader Compile Error:  %s", message);
            free(message);
        }


        GL_CALL(glAttachShader(program, computeShader));
        GL_CALL(glLinkProgram(program));
        GL_CALL(glValidateProgram(program));
        GL_CALL(glUseProgram(program));

        GLuint buff1Id, buff2Id;
        glGenBuffers(1, amp;buff1Id);
        glGenBuffers(1, amp;buff2Id);
        GLint arr1[7] = {1, 2, 3, 4, 5, 6, 7};
        GLint arr2[7];
        glBindBuffer(GL_SHADER_STORAGE_BUFFER, buff1Id);
        //glBindBuffer(GL_SHADER_STORAGE_BUFFER, buff2Id);
        glBindBufferBase(GL_SHADER_STORAGE_BUFFER,0, buff1Id);
        glBufferData(GL_SHADER_STORAGE_BUFFER, sizeof(arr1), arr1, GL_DYNAMIC_DRAW);
        //glBufferData(GL_SHADER_STORAGE_BUFFER, sizeof(arr2), arr2, GL_DYNAMIC_DRAW);

        GL_CALL(glDispatchCompute(1, 1, 1));
        GL_CALL(glMemoryBarrier(GL_BUFFER_UPDATE_BARRIER_BIT));

//        GL_CALL(glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, buff2Id));
//        GL_CALL(glBindBuffer(GL_SHADER_STORAGE_BUFFER, buff2Id));

        GLint* data = static_cast<GLint*>(glMapBufferRange(GL_SHADER_STORAGE_BUFFER, 0, 7,GL_MAP_READ_BIT));
        for(int i = 0; i < 7;   i) {
            arr2[i] = data[i];
            __android_log_print(ANDROID_LOG_INFO, "MyLog", "Num %d", arr2[i]);
        }
        glUnmapBuffer(GL_SHADER_STORAGE_BUFFER);
 

Я исправил код. Это рабочая версия программы

         GLuint program = glCreateProgram();
        GLuint computeShader = glCreateShader(GL_COMPUTE_SHADER);

        const GLchar* const shaderSrc = {
            "#version 310 esn"
            "n"
            "layout (local_size_x = 1) in;n"
            "layout(std430, binding = 0) writeonly buffer SSBO1 {n"
            "   int shader_arr1[];n"
            "};n"
            "void main(void)n"
            "{n"
            "   shader_arr1[gl_GlobalInvocationID.x] = 1;n"
            "}n"
        };

        glShaderSource(computeShader, 1, amp;shaderSrc, NULL);
        glCompileShader(computeShader);
        int resu<
        glGetShaderiv(computeShader, GL_COMPILE_STATUS, amp;result);

        if(result == GL_FALSE){
            int length;
            glGetShaderiv(computeShader, GL_INFO_LOG_LENGTH, amp;length);
            char* message = static_cast<char*>(malloc(length));
            glGetShaderInfoLog(computeShader, length, amp;length, message);
            __android_log_print(ANDROID_LOG_INFO, "MyLog", "Shader Compile Error:  %s", message);
            free(message);
        }


        GL_CALL(glAttachShader(program, computeShader));
        GL_CALL(glLinkProgram(program));
        GL_CALL(glValidateProgram(program));
        GL_CALL(glUseProgram(program));

        GLuint buff1Id, buff2Id;
        GL_CALL(glGenBuffers(1, amp;buff1Id));
        GL_CALL(glGenBuffers(1, amp;buff2Id));
        GLint arr1[7] = {1, 2, 3, 4, 5, 6, 7};
        GLint arr2[7];
        GL_CALL(glBindBuffer(GL_SHADER_STORAGE_BUFFER, buff1Id));
        GL_CALL(glBindBufferBase(GL_SHADER_STORAGE_BUFFER,0, buff1Id));
        GL_CALL(glBufferData(GL_SHADER_STORAGE_BUFFER, sizeof(arr1), arr1, GL_DYNAMIC_DRAW));

        GL_CALL(glDispatchCompute(7, 1, 1));
        GL_CALL(glMemoryBarrier(GL_BUFFER_UPDATE_BARRIER_BIT));

        GL_CALL(glBindBuffer(GL_SHADER_STORAGE_BUFFER, 0));
        GL_CALL(glBindBuffer(GL_SHADER_STORAGE_BUFFER, buff1Id));
        GL_CALL(glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, buff1Id));

        GLint* data = static_cast<GLint*>(glMapBufferRange(GL_SHADER_STORAGE_BUFFER, 0, sizeof(GLint) * 7,GL_MAP_READ_BIT));
        for(int i = 0; i < 7;   i) {
            arr2[i] = data[i];
            __android_log_print(ANDROID_LOG_INFO, "MyLog", "Num %d", arr2[i]);
        }
        glUnmapBuffer(GL_SHADER_STORAGE_BUFFER