How to set background greyscale of multiple line plots in pyopengl? - python-3.x

Question

I have a 2-D numpy array that I have plotted in Pyopengl using Pyqt. Now I want to set The background of the plot greyscale such that when the line moves up or down, its background grey color changes intensity. I am attaching images for the behaviour I want.
but all I am able to create till now is with white background like this
the code that I have written is
import OpenGL.GL as gl
import OpenGL.arrays.vbo as glvbo
from PyQt5.Qt import *
import numpy as np
import sys
VS = '''
#version 450
layout(location = 0) in vec2 position;
uniform float right;
uniform float bottom;
uniform float left;
uniform float top;
void main() {
const float far = 1.0;
const float near = -1.0;
mat4 testmat = mat4(
vec4(2.0 / (right - left), 0, 0, 0),
vec4(0, 2.0 / (top - bottom), 0, 0),
vec4(0, 0, -2.0 / (far - near), 0),
vec4(-(right + left) / (right - left), -(top + bottom) / (top - bottom), -(far + near) / (far - near), 1)
);
gl_Position = testmat * vec4(position.x, position.y, 0., 1.);
}
'''
FS = '''
#version 450
// Output variable of the fragment shader, which is a 4D vector containing the
// RGBA components of the pixel color.
uniform vec3 triangleColor;
out vec4 outColor;
void main()
{
outColor = vec4(triangleColor, 1.0);
}
'''
def compile_vertex_shader(source):
"""Compile a vertex shader from source."""
vertex_shader = gl.glCreateShader(gl.GL_VERTEX_SHADER)
gl.glShaderSource(vertex_shader, source)
gl.glCompileShader(vertex_shader)
# check compilation error
result = gl.glGetShaderiv(vertex_shader, gl.GL_COMPILE_STATUS)
if not (result):
raise RuntimeError(gl.glGetShaderInfoLog(vertex_shader))
return vertex_shader
def compile_fragment_shader(source):
"""Compile a fragment shader from source."""
fragment_shader = gl.glCreateShader(gl.GL_FRAGMENT_SHADER)
gl.glShaderSource(fragment_shader, source)
gl.glCompileShader(fragment_shader)
result = gl.glGetShaderiv(fragment_shader, gl.GL_COMPILE_STATUS)
if not (result):
raise RuntimeError(gl.glGetShaderInfoLog(fragment_shader))
return fragment_shader
def link_shader_program(vertex_shader, fragment_shader):
"""Create a shader program with from compiled shaders."""
program = gl.glCreateProgram()
gl.glAttachShader(program, vertex_shader)
gl.glAttachShader(program, fragment_shader)
gl.glLinkProgram(program)
result = gl.glGetProgramiv(program, gl.GL_LINK_STATUS)
if not (result):
raise RuntimeError(gl.glGetProgramInfoLog(program))
return program
class GLPlotWidget(QGLWidget):
def __init__(self, *args):
super(GLPlotWidget, self).__init__()
self.width, self.height = 100, 100
self.e = np.load('two.npy', mmap_mode='r')
self.vbo = glvbo.VBO(self.e)
self.count = self.vbo.shape[1]
self.right, self.left, self.top, self.bottom = self.e[0, -1, 0].min(), self.e[0, 0, 0].max(), self.e[0, :,
1].max(), self.e[-1,
:,
1].min()
# self.data = np.zeros((10, 2))
self.showMaximized()
def initializeGL(self):
vs = compile_vertex_shader(VS)
fs = compile_fragment_shader(FS)
self.shaders_program = link_shader_program(vs, fs)
def ortho_view(self):
right = gl.glGetUniformLocation(self.shaders_program, "right")
gl.glUniform1f(right, self.right)
left = gl.glGetUniformLocation(self.shaders_program, "left")
gl.glUniform1f(left, self.left)
top = gl.glGetUniformLocation(self.shaders_program, "top")
gl.glUniform1f(top, self.top)
bottom = gl.glGetUniformLocation(self.shaders_program, "bottom")
gl.glUniform1f(bottom, self.bottom)
def paintGL(self):
self.resizeGL(self.width, self.height)
gl.glDisable(gl.GL_LINE_STIPPLE)
gl.glClearColor(1, 1,1, 0)
gl.glClear(gl.GL_COLOR_BUFFER_BIT)
self.vbo.bind()
gl.glEnableVertexAttribArray(0)
gl.glVertexAttribPointer(0, 2, gl.GL_FLOAT, gl.GL_FALSE, 0, None)
gl.glUseProgram(self.shaders_program)
self.ortho_view()
uni_color = gl.glGetUniformLocation(self.shaders_program, "triangleColor")
for i in range(0, self.vbo.data.shape[0]):
gl.glUniform3f(uni_color, 0, 0, 0)
# gl.glLineWidth(1.8)
gl.glDrawArrays(gl.GL_LINE_STRIP, i * self.count, self.count)
self.vbo.unbind()
def resizeGL(self, width, height):
self.width, self.height = width, height
gl.glViewport(0, 0, width, height)
def main():
app = QApplication(sys.argv)
editor = GLPlotWidget()
editor.show()
sys.exit(app.exec_())
if __name__ == '__main__':
main()
Can anyone suggest me any method to solve this problem?
file link https://drive.google.com/file/d/1y6w35kuMguR1YczK7yMJpXU86T6qtGSv/view?usp=sharing
edit:- I tried to increase linewidth of points and set color to them but the result is not even close to satisfactory.. and I am unable to understand how to pass color in triangles?

Answer 1

Got it...I have rendered triangles and set color to get the desired result..
import OpenGL.GL as gl
import OpenGL.arrays.vbo as glvbo
from PyQt5.Qt import *
import numpy as np
import sys
import copy
VS = '''
#version 450
attribute vec2 position;
attribute vec3 a_Color;
out vec3 g_color;
void main() {
gl_Position = vec4(position.x, position.y, 0., 1.);
g_color = a_Color;
}
'''
FS = '''
#version 450
// Output variable of the fragment shader, which is a 4D vector containing the
// RGBA components of the pixel color.
in vec3 g_color;
out vec4 outColor;
void main()
{
outColor = vec4(g_color, 1.0);
}
'''
VS1 = '''
#version 450
layout(location = 0) in vec2 position;
void main() {
gl_Position = vec4(position.x, position.y, 0.0, 1.);
}
'''
FS1 = '''
#version 450
// Output variable of the fragment shader, which is a 4D vector containing the
// RGBA components of the pixel color.
uniform vec3 triangleColor;
out vec4 outColor;
void main()
{
outColor = vec4(triangleColor, 1.0);
}
'''
def compile_vertex_shader(source):
"""Compile a vertex shader from source."""
vertex_shader = gl.glCreateShader(gl.GL_VERTEX_SHADER)
gl.glShaderSource(vertex_shader, source)
gl.glCompileShader(vertex_shader)
# check compilation error
result = gl.glGetShaderiv(vertex_shader, gl.GL_COMPILE_STATUS)
if not (result):
raise RuntimeError(gl.glGetShaderInfoLog(vertex_shader))
return vertex_shader
def compile_fragment_shader(source):
"""Compile a fragment shader from source."""
fragment_shader = gl.glCreateShader(gl.GL_FRAGMENT_SHADER)
gl.glShaderSource(fragment_shader, source)
gl.glCompileShader(fragment_shader)
result = gl.glGetShaderiv(fragment_shader, gl.GL_COMPILE_STATUS)
if not (result):
raise RuntimeError(gl.glGetShaderInfoLog(fragment_shader))
return fragment_shader
def link_shader_program(vertex_shader, fragment_shader):
"""Create a shader program with from compiled shaders."""
program = gl.glCreateProgram()
gl.glAttachShader(program, vertex_shader)
gl.glAttachShader(program, fragment_shader)
gl.glLinkProgram(program)
result = gl.glGetProgramiv(program, gl.GL_LINK_STATUS)
if not (result):
raise RuntimeError(gl.glGetProgramInfoLog(program))
return program
class GLPlotWidget(QGLWidget):
def __init__(self, *args):
super(GLPlotWidget, self).__init__()
self.width, self.height = 100, 100
self.we = np.load('two.npy', mmap_mode='r')
self.e = copy.deepcopy(self.we[:, :, :])
self.e[:, :, 1] = np.interp(self.e[:, :, 1], (self.e[:, :, 1].min(), self.e[:, :, 1].max()),
(-1, 1))
self.e[:, :, 0] = np.interp(self.e[:, :, 0], (self.e[:, :, 0].min(), self.e[:, :, 0].max()),
(-1, +1))
self.vbo = glvbo.VBO(self.e)
self.count = self.vbo.shape[1]
self.showMaximized()
def initializeGL(self):
self.greyscale_data()
vs = compile_vertex_shader(VS1)
fs = compile_fragment_shader(FS1)
self.shaders_program_plot = link_shader_program(vs, fs)
def greyscale_data(self):
self.color = np.zeros((self.e.shape[1]*self.e.shape[0], 3), dtype=np.float32)
for i in range(0, 24):
a = self.e[i, :, 1].min()
b = self.e[i, :, 1].max()
c = np.interp(self.e[i, :, 1], (a, b), (0.15, 0.5))
self.color[self.e.shape[1] * i:self.e.shape[1] * (i + 1), 0] = c
self.color[self.e.shape[1] * i:self.e.shape[1] * (i + 1), 1] = c
self.color[self.e.shape[1] * i:self.e.shape[1] * (i + 1), 2] = c
self.elems = []
b = self.e.shape[1] # number of points per line
a = self.e.shape[0] # total number of arms
for i in range(0, a - 1):
for j in range(0, b - 1):
self.elems += [j + b * i, j + b * i + 1, j + b * (i + 1)]
self.elems += [j + b * (i + 1), j + b * (i + 1) + 1, j + b * i + 1]
self.elems = np.array(self.elems, dtype=np.int32)
# print(self.elems[0:100])
vs = compile_vertex_shader(VS)
fs = compile_fragment_shader(FS)
self.shaders_program = link_shader_program(vs, fs)
self.vertexbuffer = gl.glGenBuffers(1)
gl.glBindBuffer(gl.GL_ARRAY_BUFFER, self.vertexbuffer)
gl.glBufferData(gl.GL_ARRAY_BUFFER, self.e, gl.GL_DYNAMIC_DRAW)
self.elementbuffer = gl.glGenBuffers(1)
gl.glBindBuffer(gl.GL_ELEMENT_ARRAY_BUFFER, self.elementbuffer)
gl.glBufferData(gl.GL_ELEMENT_ARRAY_BUFFER, self.elems, gl.GL_DYNAMIC_DRAW)
self.colorbuffer = gl.glGenBuffers(1)
gl.glBindBuffer(gl.GL_ARRAY_BUFFER, self.colorbuffer)
gl.glBufferData(gl.GL_ARRAY_BUFFER, self.color, gl.GL_DYNAMIC_DRAW)
def ortho_view(self, i):
right = gl.glGetUniformLocation(i, "right")
gl.glUniform1f(right, self.right)
left = gl.glGetUniformLocation(i, "left")
gl.glUniform1f(left, self.left)
top = gl.glGetUniformLocation(i, "top")
gl.glUniform1f(top, self.top)
bottom = gl.glGetUniformLocation(i, "bottom")
gl.glUniform1f(bottom, self.bottom)
def greyscale(self):
gl.glUseProgram(self.shaders_program)
gl.glBindBuffer(gl.GL_ARRAY_BUFFER, self.vertexbuffer)
stride = 0 # 3*self.e.itemsize
offset = None # ctypes.c_void_p(0)
loc = gl.glGetAttribLocation(self.shaders_program, 'position')
gl.glEnableVertexAttribArray(loc)
gl.glVertexAttribPointer(loc, 2, gl.GL_FLOAT, False, stride, offset)
gl.glBindBuffer(gl.GL_ELEMENT_ARRAY_BUFFER, self.elementbuffer)
loc = gl.glGetAttribLocation(self.shaders_program, 'a_Color')
gl.glEnableVertexAttribArray(loc)
gl.glBindBuffer(gl.GL_ARRAY_BUFFER, self.colorbuffer)
gl.glVertexAttribPointer(loc, 3, gl.GL_FLOAT, False, stride, offset)
gl.glDrawElements(gl.GL_TRIANGLE_STRIP, self.elems.size, gl.GL_UNSIGNED_INT, None)
def paintGL(self):
self.resizeGL(self.width, self.height)
gl.glClearColor(1, 1, 1, 0)
gl.glClear(gl.GL_COLOR_BUFFER_BIT | gl.GL_DEPTH_BUFFER_BIT)
gl.glEnable(gl.GL_DEPTH_TEST)
self.vbo.bind()
gl.glEnableVertexAttribArray(0)
gl.glVertexAttribPointer(0, 2, gl.GL_FLOAT, gl.GL_FALSE, 0, None)
gl.glUseProgram(self.shaders_program_plot)
uni_color = gl.glGetUniformLocation(self.shaders_program_plot, "triangleColor")
for i in range(0, self.vbo.data.shape[0]):
gl.glUniform3f(uni_color, 0, 0, 0)
gl.glLineWidth(1)
gl.glDrawArrays(gl.GL_LINE_STRIP, i * self.count, self.count)
self.vbo.unbind()
self.greyscale()
gl.glUseProgram(0)
def resizeGL(self, width, height):
self.width, self.height = width, height
gl.glViewport(0, 0, width, height)
def main():
app = QApplication(sys.argv)
editor = GLPlotWidget()
editor.show()
sys.exit(app.exec_())
if __name__ == '__main__':
main()