// inicializar os shaders de texto e as variáveis correspondentes do OpenGL
public TextRenderer(int width, int height)
{
TextShader = ResourceManager.LoadShader("shaders/text.vert", "shaders/text.frag", "text");
TextShader.Use();
TextShader.SetMatrix4("projection", Matrix4.CreateOrthographicOffCenter(0, width, height, 0, -1, 1));
TextShader.SetInteger("text", 0);
VAO = GL.GenVertexArray();
VBO = GL.GenBuffer();
GL.BindVertexArray(VAO);
GL.BindBuffer(BufferTarget.ArrayBuffer, VBO);
GL.BufferData(BufferTarget.ArrayBuffer, sizeof(float) * 24, IntPtr.Zero, BufferUsageHint.DynamicDraw);
GL.EnableVertexAttribArray(0);
GL.VertexAttribPointer(0, 4, VertexAttribPointerType.Float, false, 4 * sizeof(float), 0);
GL.BindVertexArray(0);
GL.BindBuffer(BufferTarget.ArrayBuffer, 0);
}
// desenhar cada caracter do texto utilizando a fonte carregada anteriormente
// x e y denotam a posição inicial do texto, e o tamanho da fonte é utilizado
// para determinar a posição do próximo caractér
public void RenderText(string text, float x, float y, float scale, Vector3 color)
{
TextShader.Use();
TextShader.SetVector3f("textColor", color);
GL.ActiveTexture(TextureUnit.Texture0);
GL.BindVertexArray(VAO);
foreach (char c in text)
{
Character ch = Characters[c];
float xpos = x + (ch.Bearing.X * scale);
float ypos = y + ((Characters['X'].Bearing.Y - ch.Bearing.Y) * scale);
float w = ch.Size.X * scale;
float h = ch.Size.Y * scale;
float[,] vertices =
{
{ xpos, ypos + h, 0.0f, 1.0f },
{ xpos + w, ypos, 1.0f, 0.0f },
{ xpos, ypos, 0.0f, 0.0f },
{ xpos, ypos + h, 0.0f, 1.0f },
{ xpos + w, ypos + h, 1.0f, 1.0f },
{ xpos + w, ypos, 1.0f, 0.0f }
};
GL.BindTexture(TextureTarget.Texture2D, ch.TextureID);
GL.BindBuffer(BufferTarget.ArrayBuffer, VBO);
GL.BufferSubData(BufferTarget.ArrayBuffer, IntPtr.Zero, sizeof(float) * vertices.Length, vertices);
GL.BindBuffer(BufferTarget.ArrayBuffer, 0);
GL.DrawArrays(PrimitiveType.Triangles, 0, 6);
x += ch.Advance * scale;
}
GL.BindVertexArray(0);
GL.BindTexture(TextureTarget.Texture2D, 0);
}