c++ - glVertex3f 缩放问题

Question

OpenGL 的新手，请放轻松。我的任务是使用 GLFont 在我的学校项目中呈现文本，我在下面粘贴了它的呈现方法。我使用 glOrtho 将原点设置为窗口的左上角，但这会导致 GLFont 渲染字符上下颠倒的问题。我需要做的是按 -1 缩放 y 我相信，但我不知道如何更改下面的渲染器来做到这一点。有什么想法吗？

void GLFont::RenderText (const char* String, float x, float y, float z, float size)
{
    //Return if we don't have a valid glFont
    if (!ok)
    {
        throw GLFontError::InvalidFont();
    }

    //Get length of string
    int Length = strlen(String);

    //Begin rendering quads
    glBegin(GL_TRIANGLE_STRIP);

    //Loop through characters
    for (int i = 0; i < Length; i++)
    {
        //Get pointer to glFont character
        GLFONTCHAR *Char = &Font.Char[(int)String[i] - Font.IntStart];

        float dx = Char->dx*size;
        float dy = Char->dy*size;

        //Specify vertices and texture coordinates
        glTexCoord2f(Char->tx1, Char->ty2);
        glVertex3f(x, y - dy, z);
        glTexCoord2f(Char->tx1, Char->ty1);
        glVertex3f(x, y, z);
        glTexCoord2f(Char->tx2, Char->ty2);
        glVertex3f(x + dx, y - dy, z);
        glTexCoord2f(Char->tx2, Char->ty1);
        glVertex3f(x + dx, y, z);

        //Move to next character
        x += dx;
    }

    //Stop rendering quads
    glEnd();
}

Answer 1

我建议在您的代码中反转“char->ty1”和“char->ty2”，而不是缩放:

//Specify vertices and texture coordinates
glTexCoord2f(Char->tx1, Char->ty1);
glVertex3f(x, y - dy, z);
glTexCoord2f(Char->tx1, Char->ty2);
glVertex3f(x, y, z);
glTexCoord2f(Char->tx2, Char->ty1);
glVertex3f(x + dx, y - dy, z);
glTexCoord2f(Char->tx2, Char->ty2);
glVertex3f(x + dx, y, z);

这将导致通过 y 轴的反向纹理映射。

希望对您有所帮助!