renderer.py

"""
MIT License

Copyright (c) 2020 Chris Bell

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
"""

import numpy as np
import ctypes
import OpenGL
# Disable error checking for a speed increase
# OpenGL.ERROR_CHECKING = False
# Manually show errors
OpenGL.ERROR_LOGGING = False
# Ensure we use numpy arrays instead of lists to prevent copying data
OpenGL.ERROR_ON_COPY = True
import OpenGL.GL as GL
import OpenGL.GL.shaders


class Renderer:

    def __init__(self):
        """Modern OpenGL rendering class"""

        # Chip-8 display
        self.width = 64
        self.height = 32

        # Should be a multiple of 60 for proper timer operation
        self.max_fps = 60

        # Whether each pixel is on or off
        self.display_state = [[0 for y in range(self.height)] for x in range(self.width)]

        # Objects for vertex/color buffers
        self.buffer_object = np.array([])
        # Using 4 vertices per 'pixel'
        self.display_buffer = np.array([0] * (4 * self.height * self.width), np.int32)
        self.vertex_buffer = []
        self.vertex_array_object = 0

        self.attributes = {}
        self.shader = 0

        self.vertex_shader = """
        #version 330

        in vec2 position;
        in int pixel_state;
        flat out vec4 color; //don't interpolate the color
        void main()
        {
           if (pixel_state == 0) {
             color = vec4(0.1, 0.1, 0.1, 0.1);
           } else {
             color = vec4(1, 1, 1, 1);
           }
           gl_Position.xy = position.xy;
           gl_Position.zw = vec2(0.0, 1.0);
        }
        """

        self.fragment_shader = """
        #version 330
        
        flat in vec4 color;
        void main()
        {
           gl_FragColor = color;
        }
        """

    def bind_shader(self):
        """Compiles and binds the shader program"""
        self.shader = OpenGL.GL.shaders.compileProgram(
            OpenGL.GL.shaders.compileShader(self.vertex_shader, GL.GL_VERTEX_SHADER),
            OpenGL.GL.shaders.compileShader(self.fragment_shader, GL.GL_FRAGMENT_SHADER)
        )
        GL.glUseProgram(self.shader)

    def destroy(self):
        """Frees all of the allocated OpenGL resources"""
        # Unbind and delete VAO first, then VBOs
        GL.glBindVertexArray(0)
        GL.glDeleteVertexArrays(1, np.array([self.vertex_array_object]))
        GL.glBindBuffer(GL.GL_ARRAY_BUFFER, 0)
        GL.glDeleteBuffers(len(self.attributes), self.buffer_object)
        # Remove attributes
        for attribute in self.attributes.values():
            GL.glDisableVertexAttribArray(attribute)
        # Unbind shader
        GL.glUseProgram(0)

    def create_vertex_objects(self):
        """Generates the VAO and VBOs"""
        # Shader attributes
        attribute_names = ['position', 'pixel_state']
        # The VAO contains both position and color VBOs
        self.vertex_array_object = GL.glGenVertexArrays(1)
        GL.glBindVertexArray(self.vertex_array_object)
        # Generate VBOs for each of the shader attributes
        self.buffer_object = GL.glGenBuffers(len(attribute_names))
        # Enable the attributes
        for attribute in attribute_names:
            self.attributes[attribute] = GL.glGetAttribLocation(self.shader, attribute)
            GL.glEnableVertexAttribArray(self.attributes[attribute])
        # Bind the position buffer and describe/send its data
        GL.glBindBuffer(GL.GL_ARRAY_BUFFER, self.buffer_object[0])
        GL.glVertexAttribPointer(self.attributes['position'], 2, GL.GL_FLOAT, False, 0,
                                 ctypes.c_void_p(0))
        # Add vertices of 'pixels' to the buffer
        # The position of each vertex is in normalized device coordinate space
        x_increment = 2.0 / self.width
        y_increment = 2.0 / self.height
        for y in range(self.height):
            for x in range(self.width):
                # Add each 'pixel' to the list
                top_left = [-1.0 + (x * x_increment), -1.0 + (y * y_increment)]
                self.vertex_buffer.extend([top_left[0], top_left[1]])
                self.vertex_buffer.extend([top_left[0] + x_increment, top_left[1]])
                self.vertex_buffer.extend([top_left[0] + x_increment, top_left[1] + y_increment])
                self.vertex_buffer.extend([top_left[0], top_left[1] + y_increment])
        self.vertex_buffer = np.array(self.vertex_buffer, np.float32)
        # sizeof float (4) * vertex components (2) * vertices in square (4) * number of 'pixels'
        GL.glBufferData(GL.GL_ARRAY_BUFFER, 4 * 2 * 4 * self.height * self.width,
                        self.vertex_buffer, GL.GL_STATIC_DRAW)

        # Bind the color buffer and describe/send its data
        GL.glBindBuffer(GL.GL_ARRAY_BUFFER, self.buffer_object[1])
        GL.glVertexAttribPointer(self.attributes['pixel_state'], 1, GL.GL_INT, False, 0,
                                 ctypes.c_void_p(0))
        # Size of int (4) * number of vertices in a square (4) * number of 'pixels'
        GL.glBufferData(GL.GL_ARRAY_BUFFER, 4 * 4 * self.height * self.width,
                        self.display_buffer, GL.GL_DYNAMIC_DRAW)
        GL.glBindBuffer(GL.GL_ARRAY_BUFFER, 0)

    def get_pixel(self, x, y):
        return self.display_state[x][y]

    def set_pixel(self, x, y, on):
        # Get offset into buffer and update only that pixel
        start = (y * self.width * 4 * 4) + (x * 4 * 4)
        data = np.array([np.int32(on)] * 4, np.int32)
        GL.glBindBuffer(GL.GL_ARRAY_BUFFER, self.buffer_object[1])
        GL.glBufferSubData(GL.GL_ARRAY_BUFFER, start, 4 * 4, data)
        GL.glBindBuffer(GL.GL_ARRAY_BUFFER, 0)
        # Update display state for interpreter
        self.display_state[x][y] = on

    def clear_screen(self):
        for x in range(self.width):
            for y in range(self.height):
                self.set_pixel(x, y, 0)

    def render(self):
        """Draw each 'pixel'"""
        # Clear the color buffer first
        GL.glClear(GL.GL_COLOR_BUFFER_BIT)
        GL.glDrawArrays(GL.GL_QUADS, 0, 4 * self.height * self.width)