使用下面的代码,我想在opengl窗口中显示一个字符,但是如果字符多次以小尺寸的方向和垂直方向多次打印到一个我认为与该字符一样大的空间中,我将得到全部应该。谢谢。
代码(几乎全部):
import numpy
from freetype import *
import OpenGL.GL as gl
import OpenGL.GLUT as glut
text = 'H'
def makefont(filename, size):
face = Face(filename)
face.set_char_size( size*64 )
face.load_char(text, FT_LOAD_RENDER | FT_LOAD_FORCE_AUTOHINT)
bitmap = face.glyph.bitmap
data = bitmap.buffer
rows = bitmap.rows
width = bitmap.width
ascender = face.glyph.bitmap_top
descender = bitmap.rows-face.glyph.bitmap_top
height = ascender+descender
imageData = numpy.array(bitmap.buffer, numpy.uint8).reshape(rows,width)
imageData = imageData[::-1,:]
#########
textureID = gl.glGenTextures(1)
gl.glBindTexture( gl.GL_TEXTURE_2D, textureID )
gl.glTexParameterf( gl.GL_TEXTURE_2D, gl.GL_TEXTURE_MAG_FILTER, gl.GL_LINEAR )
gl.glTexParameterf( gl.GL_TEXTURE_2D, gl.GL_TEXTURE_MIN_FILTER, gl.GL_LINEAR )
gl.glTexImage2D( gl.GL_TEXTURE_2D, 0, gl.GL_RGBA, width, height, 0,
gl.GL_RGBA, gl.GL_UNSIGNED_BYTE, imageData )
#
gl.glBindTexture(gl.GL_TEXTURE_2D, textureID)
gl.glBegin(gl.GL_QUADS)
gl.glTexCoord2f(0, 0)
x = 0
y = 0
w = width
h = height
gl.glVertex2f(x, y)
gl.glTexCoord2f(1, 0)
gl.glVertex2f(x + w, y)
gl.glTexCoord2f(1, 1)
gl.glVertex2f(x + w, y + h)
gl.glTexCoord2f(0, 1)
gl.glVertex2f( x, y + h)
gl.glEnd()
def on_display( ):
gl.glClearColor(1,1,1,1)
gl.glClear(gl.GL_COLOR_BUFFER_BIT | gl.GL_DEPTH_BUFFER_BIT)
gl.glColor(0,0,0,1)
makefont( './VeraMono.ttf', 64 )
glut.glutSwapBuffers( )
def on_reshape( width, height ):
#
if __name__ == '__main__':
import sys
glut.glutInitDisplayMode( glut.GLUT_DOUBLE | glut.GLUT_RGB | glut.GLUT_DEPTH )
gl.glTexEnvf( gl.GL_TEXTURE_ENV, gl.GL_TEXTURE_ENV_MODE, gl.GL_MODULATE )
gl.glEnable( gl.GL_DEPTH_TEST )
gl.glEnable( gl.GL_BLEND )
gl.glEnable( gl.GL_COLOR_MATERIAL )
gl.glColorMaterial( gl.GL_FRONT_AND_BACK, gl.GL_AMBIENT_AND_DIFFUSE )
gl.glBlendFunc( gl.GL_SRC_ALPHA, gl.GL_ONE_MINUS_SRC_ALPHA )
gl.glEnable( gl.GL_TEXTURE_2D )
glut.glutMainLoop( )
由freetype库渲染的字形图像只有1个颜色通道。将GL_ALPHA
用于纹理的格式和内部格式。参见glTexImage2D
。此外,您还必须更改glTexImage2D
参数。GL_UNPACK_ALIGNMENT
参数定义从缓冲区读取图像时图像的每一行(一行)中第一个像素的对齐方式。默认情况下,此参数为4。字形图像的每个像素被编码为一个字节,并且图像被紧密包装。因此,字形图像的对齐方式为1,并且必须在读取图像和指定纹理之前更改参数:
GL_UNPACK_ALIGNMENT
由于未设置任何投影矩阵,因此必须在规范化的设备空间中绘制几何图形。在规范化的设备空间中,所有坐标都在[-1.0,1.0]:
GL_UNPACK_ALIGNMENT
如果要使用窗口坐标,则必须通过gl.glPixelStorei(gl.GL_UNPACK_ALIGNMENT, 1)
gl.glTexImage2D(gl.GL_TEXTURE_2D, 0, gl.GL_ALPHA, width, height, 0,
gl.GL_ALPHA, gl.GL_UNSIGNED_BYTE, imageData)
设置正交投影:
x, y, w, h = -1, -1, 2, 2
gl.glBegin(gl.GL_QUADS)
gl.glTexCoord2f(0, 0)
gl.glVertex2f(x, y)
gl.glTexCoord2f(1, 0)
gl.glVertex2f(x + w, y)
gl.glTexCoord2f(1, 1)
gl.glVertex2f(x + w, y + h)
gl.glTexCoord2f(0, 1)
gl.glVertex2f( x, y + h)
gl.glEnd()
glOrtho
完成功能glOrtho
和gl.glMatrixMode(gl.GL_PROJECTION)
gl.glLoadIdentity()
gl.glOrtho(0, width, height, 0, -1, 1)
gl.glMatrixMode(gl.GL_MODELVIEW)
:
x, y, w, h = 0, 0, width, height
gl.glBegin(gl.GL_QUADS)
gl.glTexCoord2f(0, 0)
gl.glVertex2f(x, y)
gl.glTexCoord2f(1, 0)
gl.glVertex2f(x + w, y)
gl.glTexCoord2f(1, 1)
gl.glVertex2f(x + w, y + h)
gl.glTexCoord2f(0, 1)
gl.glVertex2f( x, y + h)
gl.glEnd()
makefont