virtual_gpu_driver/src/graphics/advanced_rasterizer.py

"""
Advanced rasterizer implementation with modern features
"""
from typing import List, Tuple, Dict, Optional
import numpy as np

class AdvancedRasterizer:
    def __init__(self, driver):
        self.driver = driver
        self.tile_size = 16  # Tile size for tiled rendering
        self.early_z = True  # Enable early-Z testing
        self.msaa_samples = 1  # MSAA sample count (1=disabled)
        
    def configure(self, 
                 tile_size: int = 16, 
                 early_z: bool = True,
                 msaa_samples: int = 1):
        """Configure rasterizer settings"""
        self.tile_size = tile_size
        self.early_z = early_z
        self.msaa_samples = msaa_samples

    def setup_tiles(self, width: int, height: int) -> List[Tuple[int, int, int, int]]:
        """Split framebuffer into tiles for efficient rendering"""
        tiles = []
        for y in range(0, height, self.tile_size):
            for x in range(0, width, self.tile_size):
                tile_w = min(self.tile_size, width - x)
                tile_h = min(self.tile_size, height - y)
                tiles.append((x, y, tile_w, tile_h))
        return tiles

    def rasterize_triangle(
        self,
        v0: Tuple[float, float, float],
        v1: Tuple[float, float, float],
        v2: Tuple[float, float, float],
        attributes: Dict[str, List[float]],
        framebuffer_width: int,
        framebuffer_height: int
    ) -> List[Dict]:
        """Rasterize a triangle with perspective-correct interpolation"""
        # Convert to screen space
        def to_screen(v):
            x = (v[0] + 1) * framebuffer_width * 0.5
            y = (v[1] + 1) * framebuffer_height * 0.5
            return (x, y, v[2])  # Keep z for depth
            
        v0 = to_screen(v0)
        v1 = to_screen(v1)
        v2 = to_screen(v2)
        
        # Compute triangle bounds
        min_x = max(0, int(min(v0[0], v1[0], v2[0])))
        max_x = min(framebuffer_width - 1, int(max(v0[0], v1[0], v2[0])))
        min_y = max(0, int(min(v0[1], v1[1], v2[1])))
        max_y = min(framebuffer_height - 1, int(max(v0[1], v1[1], v2[1])))
        
        # Get relevant tiles
        tiles = []
        tile_min_x = (min_x // self.tile_size) * self.tile_size
        tile_min_y = (min_y // self.tile_size) * self.tile_size
        tile_max_x = ((max_x + self.tile_size - 1) // self.tile_size) * self.tile_size
        tile_max_y = ((max_y + self.tile_size - 1) // self.tile_size) * self.tile_size
        
        for ty in range(tile_min_y, tile_max_y + 1, self.tile_size):
            for tx in range(tile_min_x, tile_max_x + 1, self.tile_size):
                tile_w = min(self.tile_size, framebuffer_width - tx)
                tile_h = min(self.tile_size, framebuffer_height - ty)
                tiles.append((tx, ty, tile_w, tile_h))
        
        fragments = []
        for tile_x, tile_y, tile_w, tile_h in tiles:
            tile_fragments = self._rasterize_tile(
                v0, v1, v2,
                attributes,
                tile_x, tile_y,
                tile_w, tile_h
            )
            fragments.extend(tile_fragments)
            
        return fragments

    def _rasterize_tile(
        self,
        v0: Tuple[float, float, float],
        v1: Tuple[float, float, float],
        v2: Tuple[float, float, float],
        attributes: Dict[str, List[float]],
        tile_x: int,
        tile_y: int,
        tile_w: int,
        tile_h: int
    ) -> List[Dict]:
        """Rasterize a triangle within a specific tile"""
        fragments = []
        
        # Edge functions
        def edge_function(a, b, p):
            return (p[0] - a[0]) * (b[1] - a[1]) - (p[1] - a[1]) * (b[0] - a[0])
            
        # Triangle area
        area = edge_function(v0, v1, v2)
        if abs(area) < 1e-6:
            return []  # Degenerate triangle
            
        inv_area = 1.0 / area
        
        # MSAA grid
        if self.msaa_samples > 1:
            sample_positions = [
                (-0.375, -0.125), (0.375, -0.375),
                (-0.125, 0.375), (0.125, 0.125)
            ][:self.msaa_samples]
        else:
            sample_positions = [(0.0, 0.0)]
            
        # Rasterize tile
        for y in range(tile_y, tile_y + tile_h):
            for x in range(tile_x, tile_x + tile_w):
                pixel_covered = False
                sample_depths = []
                sample_barycentrics = []
                
                for sx, sy in sample_positions:
                    px = x + 0.5 + sx
                    py = y + 0.5 + sy
                    
                    # Compute barycentric coordinates
                    w0 = edge_function(v1, v2, (px, py)) * inv_area
                    w1 = edge_function(v2, v0, (px, py)) * inv_area
                    w2 = edge_function(v0, v1, (px, py)) * inv_area
                    
                    # Check if sample is inside triangle
                    if w0 >= 0 and w1 >= 0 and w2 >= 0:
                        pixel_covered = True
                        
                        # Perspective-correct interpolation
                        z0, z1, z2 = v0[2], v1[2], v2[2]
                        w = 1.0 / (w0/z0 + w1/z1 + w2/z2)
                        correct_w0 = (w0/z0) * w
                        correct_w1 = (w1/z1) * w
                        correct_w2 = (w2/z2) * w
                        
                        depth = correct_w0 * z0 + correct_w1 * z1 + correct_w2 * z2
                        sample_depths.append(depth)
                        sample_barycentrics.append((correct_w0, correct_w1, correct_w2))
                
                if pixel_covered:
                    # Average depth and barycentrics for MSAA
                    final_depth = sum(sample_depths) / len(sample_depths)
                    final_bary = tuple(
                        sum(b[i] for b in sample_barycentrics) / len(sample_barycentrics)
                        for i in range(3)
                    )
                    
                    # Interpolate vertex attributes
                    interpolated_attrs = {}
                    for attr_name, attr_values in attributes.items():
                        value = sum(
                            w * v for w, v in zip(final_bary, attr_values)
                        )
                        interpolated_attrs[attr_name] = value
                    
                    fragment = {
                        "x": x,
                        "y": y,
                        "depth": final_depth,
                        "attributes": interpolated_attrs
                    }
                    fragments.append(fragment)
                    
        return fragments

    def process_fragments(
        self,
        fragments: List[Dict],
        shader_program: Dict,
        chip_id: int = 0
    ) -> List[Dict]:
        """Process fragments using the fragment shader"""
        if not fragments:
            return []
            
        # Group fragments into warps for efficient processing
        warp_size = 32
        processed_fragments = []
        
        for i in range(0, len(fragments), warp_size):
            warp_fragments = fragments[i:i + warp_size]
            
            # Process fragments in parallel within warp
            for fragment in warp_fragments:
                # Early-Z test if enabled
                if self.early_z and not self._depth_test(fragment):
                    continue
                    
                # Execute fragment shader
                color = self._execute_fragment_shader(fragment, shader_program, chip_id)
                processed_fragment = {
                    "x": fragment["x"],
                    "y": fragment["y"],
                    "depth": fragment["depth"],
                    "color": color
                }
                processed_fragments.append(processed_fragment)
                
        return processed_fragments

    def _depth_test(self, fragment: Dict) -> bool:
        """Perform depth testing"""
        # In a real implementation, this would check against the depth buffer
        return True

    def _execute_fragment_shader(
        self,
        fragment: Dict,
        shader_program: Dict,
        chip_id: int
    ) -> Tuple[float, float, float, float]:
        """Execute fragment shader program"""
        # Get shader instructions
        instructions = shader_program.get('instructions', [])
        
        # Initialize fragment color
        color = [1.0, 1.0, 1.0, 1.0]  # Default white
        
        # Execute shader instructions
        for instr in instructions:
            op = instr.get('opcode')
            args = instr.get('args', [])
            
            if op == 'load_fragment_data':
                continue
            elif op == 'compute_color':
                # Use fragment attributes for color computation
                attrs = fragment['attributes']
                if 'color' in attrs:
                    color = attrs['color']
                else:
                    # Simple shading based on position and depth
                    x, y = fragment['x'], fragment['y']
                    depth = fragment['depth']
                    color = [
                        (x % 256) / 255.0,
                        (y % 256) / 255.0,
                        depth,
                        1.0
                    ]
            elif op == 'sample_texture':
                if 'texcoord' in fragment['attributes'] and len(args) > 0:
                    tex_coord = fragment['attributes']['texcoord']
                    # Here we would sample from the texture
                    pass
            elif op == 'compute_lighting':
                if all(attr in fragment['attributes'] for attr in ['normal', 'position']):
                    normal = fragment['attributes']['normal']
                    position = fragment['attributes']['position']
                    # Here we would compute lighting
                    pass
                    
        return tuple(color)