Interpolators for line segment, and faster transforms

Author: MichaelBell

libraries/pico_vector/pico_vector.cmake

@@ -6,4 +6,4 @@ add_library(pico_vector
 
 target_include_directories(pico_vector INTERFACE ${CMAKE_CURRENT_LIST_DIR})
 
-target_link_libraries(pico_vector pico_stdlib)
+target_link_libraries(pico_vector pico_stdlib hardware_interp)

libraries/pico_vector/pico_vector.cpp

@@ -10,44 +10,42 @@ namespace pimoroni {
   }
 
   void PicoVector::rotate(std::vector<pretty_poly::contour_t<picovector_point_type>> &contours, Point origin, float angle) {
-    pretty_poly::mat3_t t2 = pretty_poly::mat3_t::translation(origin.x, origin.y);
-    pretty_poly::mat3_t t1 = pretty_poly::mat3_t::translation(-origin.x, -origin.y);
-    angle = 2 * M_PI * (angle / 360.0f);
-    pretty_poly::mat3_t r = pretty_poly::mat3_t::rotation(angle);
+    pretty_poly::point_t<picovector_point_type> t{(picovector_point_type)origin.x, (picovector_point_type)origin.y};
+    angle = (2 * (float)M_PI / 360.f) * angle;
+    pretty_poly::mat2_t r = pretty_poly::mat2_t::rotation(angle);
     for(auto &contour : contours) {
       for(auto i = 0u; i < contour.count; i++) {
-        contour.points[i] *= t1;
+        contour.points[i] -= t;
         contour.points[i] *= r;
-        contour.points[i] *= t2;
+        contour.points[i] += t;
       }
     }
   }
 
   void PicoVector::translate(std::vector<pretty_poly::contour_t<picovector_point_type>> &contours, Point translation) {
-    pretty_poly::mat3_t t = pretty_poly::mat3_t::translation(translation.x, translation.y);
+    pretty_poly::point_t<picovector_point_type> t{(picovector_point_type)translation.x, (picovector_point_type)translation.y};
     for(auto &contour : contours) {
       for(auto i = 0u; i < contour.count; i++) {
-        contour.points[i] *= t;
+        contour.points[i] += t;
       }
     }
   }
 
   void PicoVector::rotate(pretty_poly::contour_t<picovector_point_type> &contour, Point origin, float angle) {
-    pretty_poly::mat3_t t2 = pretty_poly::mat3_t::translation(origin.x, origin.y);
-    pretty_poly::mat3_t t1 = pretty_poly::mat3_t::translation(-origin.x, -origin.y);
-    angle = 2 * M_PI * (angle / 360.0f);
-    pretty_poly::mat3_t r = pretty_poly::mat3_t::rotation(angle);
+    pretty_poly::point_t<picovector_point_type> t{(picovector_point_type)origin.x, (picovector_point_type)origin.y};
+    angle = (2 * (float)M_PI / 360.f) * angle;
+    pretty_poly::mat2_t r = pretty_poly::mat2_t::rotation(angle);
     for(auto i = 0u; i < contour.count; i++) {
-      contour.points[i] *= t1;
+      contour.points[i] -= t;
       contour.points[i] *= r;
-      contour.points[i] *= t2;
+      contour.points[i] += t;
     }
   }
 
   void PicoVector::translate(pretty_poly::contour_t<picovector_point_type> &contour, Point translation) {
-    pretty_poly::mat3_t t = pretty_poly::mat3_t::translation(translation.x, translation.y);
+    pretty_poly::point_t<picovector_point_type> t{(picovector_point_type)translation.x, (picovector_point_type)translation.y};
     for(auto i = 0u; i < contour.count; i++) {
-      contour.points[i] *= t;
+      contour.points[i] += t;
     }
   }
 
@@ -115,7 +113,7 @@ namespace pimoroni {
     pretty_poly::point_t<float> caret(0, 0);
 
     // Prepare a transformation matrix for character and offset rotation
-    angle = 2 * M_PI * (angle / 360.0f);
+    angle = (2 * (float)M_PI / 360.f) * angle;
     pretty_poly::mat3_t transform = pretty_poly::mat3_t::rotation(angle);
 
     // Align text from the bottom left

libraries/pico_vector/pretty_poly.cpp

@@ -8,6 +8,7 @@
 
 #include "pretty_poly.hpp"
 
+#include "hardware/interp.h"
 
 #ifdef PP_DEBUG
 #define debug(...) printf(__VA_ARGS__)
@@ -79,8 +80,8 @@ namespace pretty_poly {
       std::swap(sx, ex);
     }
 
-    // Early out if line is completely outside the tile
-    if (ey < 0 || sy >= (int)node_buffer_size) return;
+    // Early out if line is completely outside the tile, or has no lines
+    if (ey < 0 || sy >= (int)node_buffer_size || sy == ey) return;
 
     debug("      + line segment from %d, %d to %d, %d\n", sx, sy, ex, ey);
 
@@ -123,13 +124,16 @@ namespace pretty_poly {
       x += xinc * xjump;
     }
 
+    interp1->base[1] = full_tile_width;
+    interp1->accum[0] = x;
+
     // loop over scanlines
     while(count--) {
       // consume accumulated error
-      while(e > dy) {e -= dy; x += xinc;}
+      while(e > dy) {e -= dy; interp1->add_raw[0] = xinc;}
 
       // clamp node x value to tile bounds
-      int nx = std::max(std::min(x, full_tile_width), 0);        
+      const int nx = interp1->peek[0];
       debug("      + adding node at %d, %d\n", x, y);
       // add node to node list
       nodes[y][node_counts[y]++] = nx;
@@ -270,6 +274,14 @@ namespace pretty_poly {
     debug("  - bounds %d, %d (%d x %d)\n", polygon_bounds.x, polygon_bounds.y, polygon_bounds.w, polygon_bounds.h);
     debug("  - clip %d, %d (%d x %d)\n", settings::clip.x, settings::clip.y, settings::clip.w, settings::clip.h);
 
+    interp_hw_save_t interp1_save;
+    interp_save(interp1, &interp1_save);
+
+    interp_config cfg = interp_default_config();
+    interp_config_set_clamp(&cfg, true);
+    interp_config_set_signed(&cfg, true);
+    interp_set_config(interp1, 0, &cfg);
+    interp1->base[0] = 0;
 
     //memset(nodes, 0, node_buffer_size * sizeof(unsigned) * 32);
 
@@ -303,18 +315,21 @@ namespace pretty_poly {
         // render the tile
         rect_t bounds;
         render_nodes(tile, bounds);
-
-        tile.data += bounds.x + tile.stride * bounds.y;
-        bounds.x += tile.bounds.x;
-        bounds.y += tile.bounds.y;
-        tile.bounds = bounds.intersection(tile.bounds);
-        if (tile.bounds.empty()) {
+        if (bounds.empty()) {
           continue;
         }
 
+        tile.data += bounds.x + tile.stride * bounds.y;
+        tile.bounds.x += bounds.x;
+        tile.bounds.y += bounds.y;
+        tile.bounds.w = bounds.w;
+        tile.bounds.h = bounds.h;
+
         settings::callback(tile);
       }
     }
+
+    interp_restore(interp1, &interp1_save);
   }
 }
 

libraries/pico_vector/pretty_poly_types.hpp

@@ -14,7 +14,7 @@ namespace pretty_poly {
 
   // 3x3 matrix for coordinate transformations
   struct mat3_t {
-    float v00, v10, v20, v01, v11, v21, v02, v12, v22 = 0.0f;
+    float v00 = 0.0f, v10 = 0.0f, v20 = 0.0f, v01 = 0.0f, v11 = 0.0f, v21 = 0.0f, v02 = 0.0f, v12 = 0.0f, v22 = 0.0f;
     mat3_t() = default;
     mat3_t(const mat3_t &m) = default;
     inline mat3_t& operator*= (const mat3_t &m) {        
@@ -43,6 +43,29 @@ namespace pretty_poly {
       mat3_t r = mat3_t::identity(); r.v00 = x; r.v11 = y; return r;}
   };
 
+  // 2x2 matrix for rotations and scales
+  struct mat2_t {
+    float v00 = 0.0f, v10 = 0.0f, v01 = 0.0f, v11 = 0.0f;
+    mat2_t() = default;
+    mat2_t(const mat2_t &m) = default;
+    inline mat2_t& operator*= (const mat2_t &m) {        
+      float r00 = this->v00 * m.v00 + this->v01 * m.v10;
+      float r01 = this->v00 * m.v01 + this->v01 * m.v11;
+      float r10 = this->v10 * m.v00 + this->v11 * m.v10;
+      float r11 = this->v10 * m.v01 + this->v11 * m.v11;
+      this->v00 = r00; this->v01 = r01;
+      this->v10 = r10; this->v11 = r11;
+      return *this;
+    }
+
+    static mat2_t identity() {mat2_t m; m.v00 = m.v11 = 1.0f; return m;}
+    static mat2_t rotation(float a) {
+      float c = cosf(a), s = sinf(a); mat2_t r;
+      r.v00 = c; r.v01 = -s; r.v10 = s; r.v11 = c; return r;}
+    static mat2_t scale(float x, float y) {
+      mat2_t r; r.v00 = x; r.v11 = y; return r;}
+  };
+
   // point type for contour points
   template<typename T = int>
   struct __attribute__ ((packed)) point_t {
@@ -52,6 +75,7 @@ namespace pretty_poly {
     inline point_t& operator-= (const point_t &a) {x -= a.x; y -= a.y; return *this;}
     inline point_t& operator+= (const point_t &a) {x += a.x; y += a.y; return *this;}
     inline point_t& operator*= (const float a) {x *= a; y *= a; return *this;}
+    inline point_t& operator*= (const mat2_t &a) {this->transform(a); return *this;}
     inline point_t& operator*= (const mat3_t &a) {this->transform(a); return *this;}
     inline point_t& operator/= (const float a) {x /= a; y /= a; return *this;}
     inline point_t& operator/= (const point_t &a) {x /= a.x; y /= a.y; return *this;}
@@ -60,6 +84,11 @@ namespace pretty_poly {
       this->x = (m.v00 * tx + m.v01 * ty + m.v02);
       this->y = (m.v10 * tx + m.v11 * ty + m.v12);
     }
+    void transform(const mat2_t &m) {
+      float tx = x, ty = y;
+      this->x = (m.v00 * tx + m.v01 * ty);
+      this->y = (m.v10 * tx + m.v11 * ty);
+    }
 
   };
 
@@ -78,7 +107,7 @@ namespace pretty_poly {
     int x, y, w, h;    
     rect_t() : x(0), y(0), w(0), h(0) {}
     rect_t(int x, int y, int w, int h) : x(x), y(y), w(w), h(h) {}
-    bool empty() const {return this->w == 0 && this->h == 0;}
+    bool empty() const {return this->w == 0 || this->h == 0;}
     rect_t intersection(const rect_t &c) {
       return rect_t(std::max(this->x, c.x), std::max(this->y, c.y),
         std::max(0, std::min(this->x + this->w, c.x + c.w) - std::max(this->x, c.x)),

micropython/modules/picovector/micropython.cmake

@@ -18,4 +18,6 @@ target_compile_definitions(usermod_picovector INTERFACE
     MODULE_PICOVECTOR_ENABLED=1
 )
 
+target_link_libraries(usermod_picovector INTERFACE hardware_interp)
+
 target_link_libraries(usermod INTERFACE usermod_picovector)