我正在尝试用现代OpenGL代码创建一个程序,该程序显示一个带有纹理映射的四边形。在
应该拉伸纹理以匹配四边形大小。现在纹理重复。在
我看过一些代码,如果代码中每个顶点和映射是单独完成的,则将纹理映射到四边形。但是,我认为现在我们应该使用顶点着色器?在opengl4.5或其他版本中,这应该如何实现呢?在
"""
Open a window that displays a quad with an image on it.
"""
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *
from PIL import Image
from math import *
from time import *
class MyApplication:
""" Main application class. """
def __init__(self):
self.vao = 0
def load_texture(self, file_name):
image = Image.open(file_name)
width = image.size[0]
height = image.size[1]
image_bytes = image.convert("RGBA").tobytes ( "raw", "RGBA", 0, -1)
texture = glGenTextures(1)
glBindTexture ( GL_TEXTURE_2D, texture )
glTexParameterf ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT )
glTexParameterf ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT )
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,GL_LINEAR )
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,GL_LINEAR_MIPMAP_LINEAR )
gluBuild2DMipmaps ( GL_TEXTURE_2D, GL_RGBA, width, height, GL_RGBA, GL_UNSIGNED_BYTE, image_bytes )
return texture
def compile_shaders(self):
""" Get the shaders ready. """
# Create a triangle with three (x, y, z, ?) points.
vertex_shader_source = """
#version 450 core
void main( void)
{
// Declare a hard-coded array of positions
const vec4 vertices[4] = vec4[4](vec4(-0.5, 0.5, 0.5, 1.0),
vec4( 0.5, 0.5, 0.5, 1.0),
vec4( 0.5, -0.5, 0.5, 1.0),
vec4(-0.5, -0.5, 0.5, 1.0));
// Index into our array using gl_VertexID
gl_Position = vertices[gl_VertexID];
}
"""
vertex_shader = glCreateShader(GL_VERTEX_SHADER)
glShaderSource(vertex_shader, vertex_shader_source)
glCompileShader(vertex_shader)
# Specify the color of our fragment (RGBA)
texture = self.load_texture("test_ship.png")
fragment_shader_source = """
#version 450 core
uniform sampler2D s;
out vec4 color;
void main(void)
{
color = texture(s, gl_FragCoord.xy / textureSize(s, 0));
}
"""
fragment_shader = glCreateShader(GL_FRAGMENT_SHADER)
glShaderSource(fragment_shader, fragment_shader_source)
glCompileShader(fragment_shader)
# --- Create a program
program = glCreateProgram()
glAttachShader(program, vertex_shader)
glAttachShader(program, fragment_shader)
glLinkProgram(program)
glGenVertexArrays(1, self.vao)
glBindVertexArray(self.vao)
# --- Clean up now that we don't need these shaders anymore.
glDeleteShader(vertex_shader)
glDeleteShader(fragment_shader)
return program
def startup(self):
self.rendering_program = self.compile_shaders()
self.vertex_array_object = GLuint()
glCreateVertexArrays(1, self.vertex_array_object)
def render(self):
# Support transparency
glEnable(GL_BLEND)
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
# Get a color based on the time
color = (sin(time()), cos(time()), 0)
# Clear the screen
glClearBufferfv(GL_COLOR, 0, color)
# Tell the computer what to render
glUseProgram(self.rendering_program)
glDrawArrays(GL_QUADS, 0, 4)
# Display
glutSwapBuffers()
def animate(self):
glutPostRedisplay()
def run(self):
glutInit(sys.argv)
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH)
glutInitWindowSize(500, 500)
glutInitWindowPosition(0, 0)
glutCreateWindow(b"Simple PyOpenGL example")
self.startup()
glutIdleFunc(self.animate)
glutDisplayFunc(self.render)
glutMainLoop()
my_application = MyApplication()
my_application.run()
我认为这里有两个问题:
1)如果看到重复图案,给定当前的“包裹”和“包裹”设置,则可以假定UV坐标错误。在
在片段着色器中,使用以下计算获得UV坐标:
但是,查看四元坐标,这不会映射到[0,1]间隔,因为纹理坐标是必需的。(如果它小于或超过这个间隔,您将得到一个值的模)。在
2)如果不想重复,请使用以下方法:
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