Zachary Levy
bca19277b3
Major rework to draw rendering system. We are making a SDF first rendering system with tesselated stuff only as a fallback strategy for specific situations where SDF is particularly poorly suited Co-authored-by: Zachary Levy <zachary@sunforge.is> Reviewed-on: #17
331 lines
12 KiB
Odin
331 lines
12 KiB
Odin
package tess
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import "core:math"
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import draw ".."
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SMOOTH_CIRCLE_ERROR_RATE :: 0.1
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auto_segments :: proc(radius: f32, arc_degrees: f32) -> int {
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if radius <= 0 do return 4
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phys_radius := radius * draw.GLOB.dpi_scaling
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acos_arg := clamp(2 * math.pow(1 - SMOOTH_CIRCLE_ERROR_RATE / phys_radius, 2) - 1, -1, 1)
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theta := math.acos(acos_arg)
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if theta <= 0 do return 4
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full_circle_segments := int(math.ceil(2 * math.PI / theta))
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segments := int(f32(full_circle_segments) * arc_degrees / 360.0)
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min_segments := max(int(math.ceil(f64(arc_degrees / 90.0))), 4)
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return max(segments, min_segments)
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}
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// ----- Internal helpers -----
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// Color is premultiplied: the tessellated fragment shader passes it through directly
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// and the blend state is ONE, ONE_MINUS_SRC_ALPHA.
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solid_vertex :: proc(position: draw.Vec2, color: draw.Color) -> draw.Vertex {
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return draw.Vertex{position = position, color = draw.premultiply_color(color)}
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}
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emit_rectangle :: proc(x, y, width, height: f32, color: draw.Color, vertices: []draw.Vertex, offset: int) {
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vertices[offset + 0] = solid_vertex({x, y}, color)
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vertices[offset + 1] = solid_vertex({x + width, y}, color)
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vertices[offset + 2] = solid_vertex({x + width, y + height}, color)
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vertices[offset + 3] = solid_vertex({x, y}, color)
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vertices[offset + 4] = solid_vertex({x + width, y + height}, color)
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vertices[offset + 5] = solid_vertex({x, y + height}, color)
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}
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extrude_line :: proc(
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start, end_pos: draw.Vec2,
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thickness: f32,
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color: draw.Color,
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vertices: []draw.Vertex,
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offset: int,
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) -> int {
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direction := end_pos - start
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delta_x := direction[0]
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delta_y := direction[1]
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length := math.sqrt(delta_x * delta_x + delta_y * delta_y)
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if length < 0.0001 do return 0
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scale := thickness / (2 * length)
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perpendicular := draw.Vec2{-delta_y * scale, delta_x * scale}
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p0 := start + perpendicular
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p1 := start - perpendicular
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p2 := end_pos - perpendicular
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p3 := end_pos + perpendicular
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vertices[offset + 0] = solid_vertex(p0, color)
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vertices[offset + 1] = solid_vertex(p1, color)
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vertices[offset + 2] = solid_vertex(p2, color)
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vertices[offset + 3] = solid_vertex(p0, color)
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vertices[offset + 4] = solid_vertex(p2, color)
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vertices[offset + 5] = solid_vertex(p3, color)
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return 6
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}
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// ----- Public draw -----
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pixel :: proc(layer: ^draw.Layer, pos: draw.Vec2, color: draw.Color) {
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vertices: [6]draw.Vertex
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emit_rectangle(pos[0], pos[1], 1, 1, color, vertices[:], 0)
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draw.prepare_shape(layer, vertices[:])
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}
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triangle :: proc(
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layer: ^draw.Layer,
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v1, v2, v3: draw.Vec2,
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color: draw.Color,
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origin: draw.Vec2 = {},
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rotation: f32 = 0,
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) {
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if !draw.needs_transform(origin, rotation) {
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vertices := [3]draw.Vertex{solid_vertex(v1, color), solid_vertex(v2, color), solid_vertex(v3, color)}
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draw.prepare_shape(layer, vertices[:])
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return
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}
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bounds_min := draw.Vec2{min(v1.x, v2.x, v3.x), min(v1.y, v2.y, v3.y)}
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transform := draw.build_pivot_rotation(bounds_min, origin, rotation)
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local_v1 := v1 - bounds_min
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local_v2 := v2 - bounds_min
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local_v3 := v3 - bounds_min
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vertices := [3]draw.Vertex {
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solid_vertex(draw.apply_transform(transform, local_v1), color),
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solid_vertex(draw.apply_transform(transform, local_v2), color),
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solid_vertex(draw.apply_transform(transform, local_v3), color),
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}
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draw.prepare_shape(layer, vertices[:])
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}
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// Draw an anti-aliased triangle via extruded edge quads.
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// Interior vertices get the full premultiplied color; outer fringe vertices get BLANK (0,0,0,0).
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// The rasterizer linearly interpolates between them, producing a smooth 1-pixel AA band.
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// `aa_px` controls the extrusion width in logical pixels (default 1.0).
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// This proc emits 21 vertices (3 interior + 6 edge quads × 3 verts each).
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triangle_aa :: proc(
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layer: ^draw.Layer,
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v1, v2, v3: draw.Vec2,
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color: draw.Color,
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aa_px: f32 = draw.DFT_FEATHER_PX,
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origin: draw.Vec2 = {},
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rotation: f32 = 0,
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) {
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// Apply rotation if needed, then work in world space.
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p0, p1, p2: draw.Vec2
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if !draw.needs_transform(origin, rotation) {
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p0 = v1
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p1 = v2
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p2 = v3
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} else {
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bounds_min := draw.Vec2{min(v1.x, v2.x, v3.x), min(v1.y, v2.y, v3.y)}
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transform := draw.build_pivot_rotation(bounds_min, origin, rotation)
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p0 = draw.apply_transform(transform, v1 - bounds_min)
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p1 = draw.apply_transform(transform, v2 - bounds_min)
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p2 = draw.apply_transform(transform, v3 - bounds_min)
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}
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// Compute outward edge normals (unit length, pointing away from triangle interior).
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// Winding-independent: we check against the centroid to ensure normals point outward.
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centroid_x := (p0.x + p1.x + p2.x) / 3.0
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centroid_y := (p0.y + p1.y + p2.y) / 3.0
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edge_normal :: proc(edge_start, edge_end: draw.Vec2, centroid_x, centroid_y: f32) -> draw.Vec2 {
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delta_x := edge_end.x - edge_start.x
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delta_y := edge_end.y - edge_start.y
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length := math.sqrt(delta_x * delta_x + delta_y * delta_y)
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if length < 0.0001 do return {0, 0}
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inverse_length := 1.0 / length
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// Perpendicular: (-delta_y, delta_x) normalized
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normal_x := -delta_y * inverse_length
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normal_y := delta_x * inverse_length
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// Midpoint of the edge
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midpoint_x := (edge_start.x + edge_end.x) * 0.5
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midpoint_y := (edge_start.y + edge_end.y) * 0.5
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// If normal points toward centroid, flip it
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if normal_x * (centroid_x - midpoint_x) + normal_y * (centroid_y - midpoint_y) > 0 {
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normal_x = -normal_x
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normal_y = -normal_y
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}
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return {normal_x, normal_y}
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}
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normal_01 := edge_normal(p0, p1, centroid_x, centroid_y)
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normal_12 := edge_normal(p1, p2, centroid_x, centroid_y)
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normal_20 := edge_normal(p2, p0, centroid_x, centroid_y)
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extrude_distance := aa_px * draw.GLOB.dpi_scaling
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// Outer fringe vertices: each edge vertex extruded outward
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outer_0_01 := p0 + normal_01 * extrude_distance
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outer_1_01 := p1 + normal_01 * extrude_distance
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outer_1_12 := p1 + normal_12 * extrude_distance
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outer_2_12 := p2 + normal_12 * extrude_distance
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outer_2_20 := p2 + normal_20 * extrude_distance
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outer_0_20 := p0 + normal_20 * extrude_distance
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// Premultiplied interior color (solid_vertex does premul internally).
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// Outer fringe is BLANK = {0,0,0,0} which is already premul.
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transparent := draw.BLANK
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// 3 interior + 6 × 3 edge-quad = 21 vertices
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vertices: [21]draw.Vertex
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// Interior triangle
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vertices[0] = solid_vertex(p0, color)
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vertices[1] = solid_vertex(p1, color)
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vertices[2] = solid_vertex(p2, color)
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// Edge quad: p0→p1 (2 triangles)
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vertices[3] = solid_vertex(p0, color)
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vertices[4] = solid_vertex(p1, color)
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vertices[5] = solid_vertex(outer_1_01, transparent)
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vertices[6] = solid_vertex(p0, color)
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vertices[7] = solid_vertex(outer_1_01, transparent)
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vertices[8] = solid_vertex(outer_0_01, transparent)
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// Edge quad: p1→p2 (2 triangles)
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vertices[9] = solid_vertex(p1, color)
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vertices[10] = solid_vertex(p2, color)
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vertices[11] = solid_vertex(outer_2_12, transparent)
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vertices[12] = solid_vertex(p1, color)
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vertices[13] = solid_vertex(outer_2_12, transparent)
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vertices[14] = solid_vertex(outer_1_12, transparent)
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// Edge quad: p2→p0 (2 triangles)
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vertices[15] = solid_vertex(p2, color)
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vertices[16] = solid_vertex(p0, color)
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vertices[17] = solid_vertex(outer_0_20, transparent)
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vertices[18] = solid_vertex(p2, color)
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vertices[19] = solid_vertex(outer_0_20, transparent)
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vertices[20] = solid_vertex(outer_2_20, transparent)
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draw.prepare_shape(layer, vertices[:])
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}
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triangle_lines :: proc(
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layer: ^draw.Layer,
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v1, v2, v3: draw.Vec2,
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color: draw.Color,
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thickness: f32 = draw.DFT_STROKE_THICKNESS,
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origin: draw.Vec2 = {},
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rotation: f32 = 0,
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temp_allocator := context.temp_allocator,
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) {
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vertices := make([]draw.Vertex, 18, temp_allocator)
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defer delete(vertices, temp_allocator)
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write_offset := 0
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if !draw.needs_transform(origin, rotation) {
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write_offset += extrude_line(v1, v2, thickness, color, vertices, write_offset)
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write_offset += extrude_line(v2, v3, thickness, color, vertices, write_offset)
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write_offset += extrude_line(v3, v1, thickness, color, vertices, write_offset)
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} else {
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bounds_min := draw.Vec2{min(v1.x, v2.x, v3.x), min(v1.y, v2.y, v3.y)}
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transform := draw.build_pivot_rotation(bounds_min, origin, rotation)
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transformed_v1 := draw.apply_transform(transform, v1 - bounds_min)
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transformed_v2 := draw.apply_transform(transform, v2 - bounds_min)
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transformed_v3 := draw.apply_transform(transform, v3 - bounds_min)
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write_offset += extrude_line(transformed_v1, transformed_v2, thickness, color, vertices, write_offset)
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write_offset += extrude_line(transformed_v2, transformed_v3, thickness, color, vertices, write_offset)
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write_offset += extrude_line(transformed_v3, transformed_v1, thickness, color, vertices, write_offset)
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}
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if write_offset > 0 {
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draw.prepare_shape(layer, vertices[:write_offset])
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}
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}
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triangle_fan :: proc(
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layer: ^draw.Layer,
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points: []draw.Vec2,
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color: draw.Color,
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origin: draw.Vec2 = {},
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rotation: f32 = 0,
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temp_allocator := context.temp_allocator,
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) {
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if len(points) < 3 do return
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triangle_count := len(points) - 2
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vertex_count := triangle_count * 3
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vertices := make([]draw.Vertex, vertex_count, temp_allocator)
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defer delete(vertices, temp_allocator)
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if !draw.needs_transform(origin, rotation) {
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for i in 1 ..< len(points) - 1 {
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idx := (i - 1) * 3
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vertices[idx + 0] = solid_vertex(points[0], color)
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vertices[idx + 1] = solid_vertex(points[i], color)
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vertices[idx + 2] = solid_vertex(points[i + 1], color)
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}
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} else {
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bounds_min := draw.Vec2{max(f32), max(f32)}
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for point in points {
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bounds_min.x = min(bounds_min.x, point.x)
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bounds_min.y = min(bounds_min.y, point.y)
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}
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transform := draw.build_pivot_rotation(bounds_min, origin, rotation)
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for i in 1 ..< len(points) - 1 {
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idx := (i - 1) * 3
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vertices[idx + 0] = solid_vertex(draw.apply_transform(transform, points[0] - bounds_min), color)
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vertices[idx + 1] = solid_vertex(draw.apply_transform(transform, points[i] - bounds_min), color)
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vertices[idx + 2] = solid_vertex(draw.apply_transform(transform, points[i + 1] - bounds_min), color)
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}
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}
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draw.prepare_shape(layer, vertices)
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}
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triangle_strip :: proc(
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layer: ^draw.Layer,
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points: []draw.Vec2,
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color: draw.Color,
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origin: draw.Vec2 = {},
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rotation: f32 = 0,
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temp_allocator := context.temp_allocator,
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) {
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if len(points) < 3 do return
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triangle_count := len(points) - 2
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vertex_count := triangle_count * 3
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vertices := make([]draw.Vertex, vertex_count, temp_allocator)
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defer delete(vertices, temp_allocator)
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if !draw.needs_transform(origin, rotation) {
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for i in 0 ..< triangle_count {
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idx := i * 3
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if i % 2 == 0 {
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vertices[idx + 0] = solid_vertex(points[i], color)
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vertices[idx + 1] = solid_vertex(points[i + 1], color)
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vertices[idx + 2] = solid_vertex(points[i + 2], color)
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} else {
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vertices[idx + 0] = solid_vertex(points[i + 1], color)
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vertices[idx + 1] = solid_vertex(points[i], color)
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vertices[idx + 2] = solid_vertex(points[i + 2], color)
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}
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}
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} else {
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bounds_min := draw.Vec2{max(f32), max(f32)}
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for point in points {
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bounds_min.x = min(bounds_min.x, point.x)
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bounds_min.y = min(bounds_min.y, point.y)
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}
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transform := draw.build_pivot_rotation(bounds_min, origin, rotation)
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for i in 0 ..< triangle_count {
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idx := i * 3
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if i % 2 == 0 {
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vertices[idx + 0] = solid_vertex(draw.apply_transform(transform, points[i] - bounds_min), color)
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vertices[idx + 1] = solid_vertex(draw.apply_transform(transform, points[i + 1] - bounds_min), color)
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vertices[idx + 2] = solid_vertex(draw.apply_transform(transform, points[i + 2] - bounds_min), color)
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} else {
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vertices[idx + 0] = solid_vertex(draw.apply_transform(transform, points[i + 1] - bounds_min), color)
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vertices[idx + 1] = solid_vertex(draw.apply_transform(transform, points[i] - bounds_min), color)
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vertices[idx + 2] = solid_vertex(draw.apply_transform(transform, points[i + 2] - bounds_min), color)
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}
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}
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}
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draw.prepare_shape(layer, vertices)
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}
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