C++ 如何将stb_truetype位图加载到和OpenGL纹理中

我有以下代码从std:：wstring创建位图，然后使用它保存到图像中

#include <stb_image_write.h>
#include <stb_truetype.h>

unsigned char buffer[24 << 20];
stbtt_fontinfo font;

fread(buffer, 1, 1000000, fopen("../assets/fonts/unibody_8.ttf", "rb"));
stbtt_InitFont(&font, buffer, 0);
float scale = stbtt_ScaleForPixelHeight(&font, 48 * 2);

int ascent, descent;
stbtt_GetFontVMetrics(&font, &ascent, &descent, 0);
int baseline = (int)(ascent * scale);

int width = 0;
for (const auto &character : content) {
  int advance, leftSideBearing;
  stbtt_GetCodepointHMetrics(&font, character, &advance, &leftSideBearing);
  texture.width += advance * scale;
}

int height = (ascent + (descent * -1)) * scale;

std::vector<unsigned char> pixels(
  (size_t)(texture.width * texture.height), (unsigned char)0);

float xpos = 0.0f;
int characterIndex = 0;
while (content[characterIndex]) {
  int advance, lsb, x0, y0, x1, y1;
  float x_shift = xpos - (float)floor(xpos);

  stbtt_GetCodepointHMetrics(
    &font, content[characterIndex], &advance, &lsb);

  stbtt_GetCodepointBitmapBoxSubpixel(
    &font,
    content[characterIndex],
    scale,
    scale,
    x_shift,
    0,
    &x0,
    &y0,
    &x1,
    &y1);

  auto stride = width * (baseline + y0) + (int)xpos + x0;
  stbtt_MakeCodepointBitmapSubpixel(
    &font,
    &pixels.at(0) + stride,
    x1 - x0,
    y1 - y0,
    texture.width,
    scale,
    scale,
    x_shift,
    0,
    content[characterIndex]);

  xpos += (advance * scale);

  if (content[characterIndex + 1]) {
    int kernAdvance = stbtt_GetCodepointKernAdvance(
      &font, content[characterIndex], content[characterIndex + 1]);
    xpos += scale * kernAdvance;
  }

  ++characterIndex;
}

// This step works fine, this means that the data in pixels is good
stbi_write_png("image.png", width, height, 1, pixels.data(), 0);

我试图捕获异常，但程序只是静静地崩溃了，所以我不知道如何处理它。

这

你告诉德国劳埃德船级社每像素32位，红、绿、蓝和阿尔法各8位。因此，GL将读取比您提供的内存多4倍的内存，读取超过缓冲区的末尾，如果您幸运的话，会在以后的某个时间由于某些分段错误而导致应用程序崩溃

您没有指定正在使用的总账版本。对于现代GL，可以使用

GL_RED

作为纹理格式，并直接通过着色器或纹理旋转设置处理到RGBA的转换。对于古老的传统GL，您可能必须使用

GL\u亮度

格式

您还必须注意，GL的默认解包行对齐方式为4字节，因此，如果宽度不是4的倍数，您还必须显式设置

glPixelStore（GL\u解包\u对齐方式，1）

，以匹配数据对齐方式

uint32_t id = 0;
glGenTextures(1, &id);
glBindTexture(GL_TEXTURE_2D, id);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

// This crashes the application, I guess it's because the data in pixels is not valid for an OpenGL texture
glTexImage2D(
  GL_TEXTURE_2D,
  0,
  GL_RGBA,
  width,
  height,
  0,
  GL_RGBA,
  GL_UNSIGNED_BYTE,
  pixels.data());

std::vector<unsigned char> pixels(
  (size_t)(texture.width * texture.height), (unsigned char)0);

glTexImage2D(
  GL_TEXTURE_2D,
  0,
  GL_RGBA,
  width,
  height,
  0,
  GL_RGBA,
  GL_UNSIGNED_BYTE,
  pixels.data());