/// <summary>
/// Information of rendering a glyph.
/// 绘制一个字符（串）所需要的信息。
/// </summary>
/// <param name="characters">The glyph(a character or a string).此字符（串）。</param>
/// <param name="leftTop">UV of left top.此字符的字形在纹理的横向偏移量（左上角uv）</param>
/// <param name="rightBottom">UV of right bottom.此字符的字形在纹理的纵向偏移量（右下角uv）</param>
/// <param name="textureIndex">Index of the the texture which this glyph belongs to in the 2D texture array.此字符所在的纹理，在二维纹理数组中的索引。</param>
public GlyphInfo(string characters, vec2 leftTop, vec2 rightBottom, int textureIndex)
{
this.characters = characters;
var leftBottom = new vec2(leftTop.x, rightBottom.y);
var rightTop = new vec2(rightBottom.x, leftTop.y);
this.quad = new QuadStruct(leftTop, leftBottom, rightBottom, rightTop);
this.textureIndex = textureIndex;
}
/// <summary>
/// start from (0, 0) to the right.
/// </summary>
/// <param name="text"></param>
/// <param name="server"></param>
/// <param name="totalWidth"></param>
/// <param name="totalHeight"></param>
unsafe private void PositionPass(string text, GlyphServer server,
out float totalWidth, out float totalHeight)
{
int textureWidth = server.TextureWidth;
int textureHeight = server.TextureHeight;
VertexBuffer buffer = this.positionBuffer;
var positionArray = (QuadStruct *)buffer.MapBuffer(MapBufferAccess.ReadWrite);
const float height = 2.0f; // let's say height is 2.0f.
totalWidth = 0;
totalHeight = height;
int index = 0;
foreach (var c in text)
{
GlyphInfo glyphInfo;
float wByH = 0;
if (server.GetGlyphInfo(c, out glyphInfo))
{
float w = (glyphInfo.quad.rightBottom.x - glyphInfo.quad.leftBottom.x) * textureWidth;
float h = (glyphInfo.quad.rightBottom.y - glyphInfo.quad.rightTop.y) * textureHeight;
wByH = height * w / h;
}
else
{
// put an empty glyph(square) here.
wByH = height * 1.0f / 1.0f;
}
var leftTop = new vec2(totalWidth, 1f);
var leftBottom = new vec2(totalWidth, -1f);
var rightBottom = new vec2(totalWidth + wByH, -1f);
var rightTop = new vec2(totalWidth + wByH, 1f);
positionArray[index++] = new QuadStruct(leftTop, leftBottom, rightBottom, rightTop);
totalWidth += wByH;
}
// move to center.
const float scale = 1f;
for (int i = 0; i < text.Length; i++)
{
QuadStruct quad = positionArray[i];
var newPos = new QuadStruct(
// y is already in [-1, 1], so just shrink x to [-1, 1]
new vec2(quad.leftTop.x / totalWidth * 2.0f - 1f, quad.leftTop.y) * scale,
new vec2(quad.leftBottom.x / totalWidth * 2.0f - 1f, quad.leftBottom.y) * scale,
new vec2(quad.rightBottom.x / totalWidth * 2.0f - 1f, quad.rightBottom.y) * scale,
new vec2(quad.rightTop.x / totalWidth * 2.0f - 1f, quad.rightTop.y) * scale
);
positionArray[i] = newPos;
}
buffer.UnmapBuffer();
}