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Luzifer's questions

Martin Hope
Luzifer
Asked: 2020-01-29 21:57:07 +0000 UTC
  • 2

大家好！

有一个任务

  1. 编写一个共享库（对于 windows .dll，对于 Linux .so）
  2. 库的头文件必须放在相应的文件夹中。（对于 Linux /usr/local/include/{library_name}/*）
  3. 应该可以在正在开发的应用程序中使用头文件。

目前我有 CMakeLists.txt

cmake_minimum_required(VERSION 3.13)

set(PROJECT_VERSION "0.0.1")

project(mylib VERSION ${PROJECT_VERSION})

set(CMAKE_CXX_STANDARD 17)

include(CMakeSources.cmake)
add_library(mylib SHARED ${MY_LIB_HEADERS} ${MY_LIB_SOURCES})

set_target_properties(mylib PROPERTIES
        VERSION ${PROJECT_VERSION}
        SOVERSION ${PROJECT_VERSION})

include(GNUInstallDirs)
set(MY_LIB_LIBRARY_DESTINATION ${CMAKE_INSTALL_LIBDIR})
set(MY_LIB_HEADERS_DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/mylib)

INSTALL(TARGETS mylib
        LIBRARY DESTINATION ${MY_LIB_LIBRARY_DESTINATION})

INSTALL(DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/
        PUBLIC_HEADER DESTINATION ${MY_LIB_HEADERS_DESTINATION}
        FILES_MATCHING PATTERN "*.h")

几乎可以满足所有要求。第 3 点有错误。

例如：我有两个头文件Ah和Bh，Bh包含Ah（#include "Ah"）。

执行 make install 命令后，这些文件被移动到

  • /usr/local/include/mylib/啊
  • /usr/local/include/mylib/Bh

现在，当我尝试在另一个项目中使用 Bh 时，我得到了错误

/usr/local/include/mylib/Bh:1：致命错误：找不到“Ah”文件#include“Ah”

请帮我解决这个问题。

cmake
Martin Hope
Luzifer
Asked: 2020-07-02 04:37:11 +0000 UTC
  • 1

如何正确组织立方体照明的法线？

  1. 立方体顶点：

    std::vector<Vertex> vertices = {
        Vertex {Position: glm::vec3(-0.5, -0.5, -0.5)},
        Vertex {Position: glm::vec3(-0.5,  0.5, -0.5)},
        Vertex {Position: glm::vec3( 0.5,  0.5, -0.5)},
        Vertex {Position: glm::vec3( 0.5, -0.5, -0.5)},
        Vertex {Position: glm::vec3(-0.5, -0.5,  0.5)},
        Vertex {Position: glm::vec3(-0.5,  0.5,  0.5)},
        Vertex {Position: glm::vec3( 0.5,  0.5,  0.5)},
        Vertex {Position: glm::vec3( 0.5, -0.5,  0.5)}};

  2. 立方体索引：

    std::vector<unsigned int> indices = {
        0, 1, 2,  0, 2, 3, // front
        4, 5, 6,  4, 6, 7, // back
        0, 1, 5,  0, 5, 4, // left
        2, 6, 3,  3, 6, 7, // right
        1, 5, 2,  2, 5, 6, // up
        9, 4, 3,  3, 4, 7  // bottom
};

  3. 立方体是使用 drawElements 方法绘制的。

如果我正确理解了理论......那么计算颜色，立方体的每个顶点应该有3个法线，如图所示。

但我不知道如何将 3 个法线传递给一个顶点的着色器？

并且如果仍然成功转移，如何确定当前人脸所需的法线？（因为我们每个顶点有 3 个法线）

opengl
Martin Hope
Luzifer
Asked: 2020-05-26 21:30:29 +0000 UTC
  • 2

我需要将有关 ELF 的信息放入标题结构中，其中结构的字段是 64 位值。当我尝试以通常的方式阅读它们时，我在所有领域都得到 0。您能告诉我如何使下面的代码正常工作吗？

  1. 用于读取 ELF 字节的 hexdump 文件

    00000000  7f 45 4c 46 02 01 01 00  00 00 00 00 00 00 00 00  |.ELF............|
00000010  01 00 3e 00 01 00 00 00  00 00 00 00 00 00 00 00  |..>.............|
00000020  00 00 00 00 00 00 00 00  40 00 00 00 00 00 00 00  |........@.......|
00000030  00 00 00 00 40 00 00 00  00 00 40 00 05 00 02 00  |....@.....@.....|
00000040  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000080  01 00 00 00 01 00 00 00  06 00 00 00 00 00 00 00  |................|
00000090  00 00 00 00 00 00 00 00  80 01 00 00 00 00 00 00  |................|
000000a0  0c 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000b0  10 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000c0  07 00 00 00 03 00 00 00  00 00 00 00 00 00 00 00  |................|
000000d0  00 00 00 00 00 00 00 00  90 01 00 00 00 00 00 00  |................|
000000e0  21 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |!...............|
000000f0  01 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000100  11 00 00 00 02 00 00 00  00 00 00 00 00 00 00 00  |................|
00000110  00 00 00 00 00 00 00 00  c0 01 00 00 00 00 00 00  |................|
00000120  60 00 00 00 00 00 00 00  04 00 00 00 03 00 00 00  |`...............|
00000130  04 00 00 00 00 00 00 00  18 00 00 00 00 00 00 00  |................|
00000140  19 00 00 00 03 00 00 00  00 00 00 00 00 00 00 00  |................|
00000150  00 00 00 00 00 00 00 00  20 02 00 00 00 00 00 00  |........ .......|
00000160  0e 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000170  01 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000180  b8 3c 00 00 00 bf 00 00  00 00 0f 05 00 00 00 00  |.<..............|
00000190  00 2e 74 65 78 74 00 2e  73 68 73 74 72 74 61 62  |..text..shstrtab|
000001a0  00 2e 73 79 6d 74 61 62  00 2e 73 74 72 74 61 62  |..symtab..strtab|
000001b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
000001d0  00 00 00 00 00 00 00 00  01 00 00 00 04 00 f1 ff  |................|
000001e0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001f0  00 00 00 00 03 00 01 00  00 00 00 00 00 00 00 00  |................|
00000200  00 00 00 00 00 00 00 00  07 00 00 00 10 00 01 00  |................|
00000210  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000220  00 65 78 31 2e 73 00 5f  73 74 61 72 74 00 00 00  |.ex1.s._start...|

  2. 将ELF读入结构的源代码

    #include <iostream>
#include <fstream>
#include <stdint.h>

/* Type for a 16-bit quantity.  */
typedef uint16_t Elf64_Half;

/* Types for signed and unsigned 32-bit quantities.  */
typedef uint32_t Elf64_Word;

/* Type of addresses.  */
typedef uint64_t Elf64_Addr;

/* Type of file offsets.  */
typedef uint64_t Elf64_Off;

/* The ELF file header.  This appears at the start of every ELF file.  */

#define EI_NIDENT (16)

typedef struct
{
  unsigned char e_ident[EI_NIDENT]; /* Magic number and other info */
  Elf64_Half      e_type;                   /* Object file type */
  Elf64_Half      e_machine;              /* Architecture */
  Elf64_Word      e_version;            /* Object file version */
  Elf64_Addr      e_entry;            /* Entry point virtual address */
  Elf64_Off     e_phoff;              /* Program header table file offset */
  Elf64_Off     e_shoff;              /* Section header table file offset */
  Elf64_Word      e_flags;            /* Processor-specific flags */
  Elf64_Half    e_ehsize;             /* ELF header size in bytes */
  Elf64_Half    e_phentsize;            /* Program header table entry size */
  Elf64_Half    e_phnum;                /* Program header table entry count */
  Elf64_Half      e_shentsize;          /* Section header table entry size */
  Elf64_Half    e_shnum;                /* Section header table entry count */
  Elf64_Half      e_shstrndx;           /* Section header string table index */
} Elf64_Ehdr;

int main(int argc, char const *argv[])
{
    Elf64_Ehdr ehdr = {};

    std::ifstream ifs;

    ifs.open("ex1.o", std::ios::binary|std::ios::in);

    for (int i = 0; i < EI_NIDENT; i++)
    {
      ifs >> ehdr.e_ident[i];
    }

    ifs >> ehdr.e_type;
    ifs >> ehdr.e_machine;
    ifs >> ehdr.e_version;
    ifs >> ehdr.e_entry;
    ifs >> ehdr.e_phoff;
    ifs >> ehdr.e_shoff;
    ifs >> ehdr.e_flags;
    ifs >> ehdr.e_ehsize;
    ifs >> ehdr.e_phentsize;
    ifs >> ehdr.e_phnum;
    ifs >> ehdr.e_shentsize;
    ifs >> ehdr.e_shnum;
    ifs >> ehdr.e_shstrndx;

    return 0;
}

  3. 结果：除 e_ident 之外的所有字段都包含 0

c++