Merge pull request #865 from MihailRis/canvas-line-fixes

Canvas line-related fixes

dev/tests/canvas_lines.lua

@@ -0,0 +1,51 @@
+local W, H = 128, 128
+
+local canvas = Canvas({W, H})
+canvas:clear(0xff202020)
+
+local WHITE = 0xffffffff
+local RED  = 0xffff4040
+local GREEN = 0xff40ff40
+local BLUE = 0xff4080ff
+local YELLOW = 0xffffff40
+
+-- border
+canvas:line(0, 0, W - 1, 0, WHITE)
+canvas:line(W - 1, 0, W - 1, H - 1, WHITE)
+canvas:line(W - 1, H - 1, 0, H - 1, WHITE)
+canvas:line(0, H - 1, 0, 0, WHITE)
+
+-- horizontal
+canvas:line(-40, 16, W + 40, 16, RED)
+canvas:line(-40, H / 2, W + 40, H / 2, RED)
+canvas:line(-40, H - 17, W + 40, H - 17, RED)
+
+-- vertical
+canvas:line(16, -40, 16, H + 40, GREEN)
+canvas:line(W / 2, -40, W / 2, H + 40, GREEN)
+canvas:line(W - 17, -40, W - 17, H + 40, GREEN)
+
+-- diagonals
+canvas:line(-40, -40, W + 40, H + 40, BLUE)
+canvas:line(-40, H + 40, W + 40, -40, BLUE)
+
+canvas:line(W / 2, -40, W + 40, H / 2, BLUE)
+canvas:line(-40, H / 2, W / 2, H + 40, BLUE)
+
+-- outer
+canvas:line(-30, -30, 20, 20, YELLOW)
+canvas:line(W - 20, H - 20, W + 30, H + 30, YELLOW)
+
+canvas:line(W + 30, -30, W - 20, 20, YELLOW)
+canvas:line(-30, H + 30, 20, H - 20, YELLOW)
+
+-- completely outside
+canvas:line(-50, -20, -10, H + 20, 0xffff00ff)
+canvas:line(W + 10, -20, W + 50, H + 20, 0xffff00ff)
+canvas:line(-20, -20, W + 20, -10, 0xffff00ff)
+canvas:line(-20, H + 10, W + 20, H + 30, 0xffff00ff)
+
+local expected = Canvas.decode(
+    file.read_bytes("script:attachments/line_clipping_test.png"), "png"
+)
+asserts.equals(expected, canvas)

res/modules/internal/asserts.lua

@@ -1,8 +1,77 @@
 local this = {}
+local app = __vc_app
 
-function this.equals(expected, fact)
+local function diff_canvas(expected, fact)
+    this.equals(expected.width, fact.width, "image width")
+    this.equals(expected.width, fact.width, "image height")
+
+    local diff = Canvas({expected.width, expected.height})
+
+    local mismatches = 0
+
+    for y = 0, expected.height - 1 do
+        for x = 0, expected.width - 1 do
+            local ca = expected:at(x, y)
+            local cb = fact:at(x, y)
+
+            if ca == cb then
+                diff:set(x, y, ca)
+            else
+                diff:set(x, y, 0xff0000ff)
+                mismatches = mismatches + 1
+            end
+        end
+    end
+
+    return diff, mismatches
+end
+
+local TEST_ARTIFACTS_PATH = "export:test-results"
+
+local function get_test_artifact_path(name)
+    local path = TEST_ARTIFACTS_PATH
+    if not file.isdir(path) then
+        file.mkdirs(path)
+    end
+    return file.join(path, name)
+end
+
+function this.equals(expected, fact, prefix)
+    local mt = getmetatable(expected)
+    if mt == Canvas then
+        local diff, mismatches = diff_canvas(expected, fact)
+        if mismatches > 0 then
+            prefix = prefix or app.script or base64.encode_urlsafe(random.bytes(6))
+            local path_diff = get_test_artifact_path(
+                string.format("%s.diff.png", prefix)
+            )
+            local path_fact = get_test_artifact_path(
+                string.format("%s.fact.png", prefix)
+            )
+            local path_expected = get_test_artifact_path(
+                string.format("%s.expected.png", prefix)
+            )
+            file.write_bytes(path_diff, diff:encode('png'))
+            file.write_bytes(path_fact, fact:encode('png'))
+            file.write_bytes(path_expected, expected:encode('png'))
+            local total_pixels = expected.width * expected.height
+            assert(mismatches == 0, string.format(
+                "%s pixels of %s (%s%%) are different, diff saved as %s",
+                mismatches,
+                total_pixels,
+                math.round(mismatches / total_pixels * 100, 2),
+                string.escape(path_diff))
+            )
+        end
+        return
+    end
+    if prefix then
+        prefix = prefix .. " "
+    else
+        prefix = ""
+    end
     assert(fact == expected, string.format(
-        "(fact == expected) assertion failed\n  Expected: %s\n  Fact:     %s",
+        prefix .. "(fact == expected) assertion failed\n  Expected: %s\n  Fact:     %s",
         expected, fact
     ))
 end

src/coders/png.cpp

@@ -49,9 +49,9 @@ static util::Buffer<ubyte> write_to_memory(uint width, uint height, const ubyte*
     png_write_info(png_ptr, info_ptr);
 
     auto row = std::make_unique<png_byte[]>(pixsize * width);
-    for (uint y = 0; y < height; y++) {
-        for (uint x = 0; x < width; x++) {
-            for (uint i = 0; i < pixsize; i++) {
+    for (int y = height-1; y >= 0; y--) {
+        for (int x = 0; x < width; x++) {
+            for (int i = 0; i < pixsize; i++) {
                 row[x * pixsize + i] =
                     (png_byte)data[(y * width + x) * pixsize + i];
             }

src/graphics/core/ImageData.cpp

@@ -1,5 +1,7 @@
 #include "ImageData.hpp"
 
+#include "debug/Logger.hpp"
+
 #include <glm/glm.hpp>
 #include <assert.h>
 #include <stdexcept>
@@ -7,6 +9,8 @@
 #include <cmath>
 #include <algorithm>
 
+static debug::Logger logger("image-data");
+
 ImageData::ImageData(ImageFormat format, uint width, uint height) 
     : format(format), width(width), height(height) {
     size_t pixsize;
@@ -106,47 +110,83 @@ std::unique_ptr<ImageData> ImageData::cropped(int x, int y, int width, int heigh
     return subImage;
 }
 
-static bool clip_line(int& x1, int& y1, int& x2, int& y2, int width, int height) {
-    const int left = 0;
-    const int right = width;
-    const int bottom = 0;
-    const int top = height;
+static bool clip_line(
+    int& x0, int& y0, int& x1, int& y1, int width, int height
+) {
+    if (width <= 0 || height <= 0) {
+        return false;
+    }
+    constexpr int INSIDE = 0;
+    constexpr int LEFT = 1;
+    constexpr int RIGHT = 2;
+    constexpr int BOTTOM = 4;
+    constexpr int TOP = 8;
 
-    int dx = x2 - x1;
-    int dy = y2 - y1;
+    const int xmin = 0;
+    const int ymin = 0;
+    const int xmax = width - 1;
+    const int ymax = height - 1;
 
-    float t0 = 0.0f;
-    float t1 = 1.0f;
+    auto outcode = [&](int x, int y) {
+        int code = INSIDE;
 
-    auto clip = [](int p, int q, float& t0, float& t1) {
-        if (p == 0) {
-            return q >= 0;
-        }
-        float t = static_cast<float>(q) / p;
-        if (p < 0) {
-            if (t > t1) return false;
-            if (t > t0) t0 = t;
-        } else {
-            if (t < t0) return false;
-            if (t < t1) t1 = t;
-        }
-        return true;
+        if (x < xmin)
+            code |= LEFT;
+        else if (x > xmax)
+            code |= RIGHT;
+
+        if (y < ymin)
+            code |= BOTTOM;
+        else if (y > ymax)
+            code |= TOP;
+
+        return code;
     };
 
-    if (!clip(-dx, x1 - left, t0, t1)) return false;
-    if (!clip( dx, right - x1, t0, t1)) return false;
-    if (!clip(-dy, y1 - bottom, t0, t1)) return false;
-    if (!clip( dy, top - y1, t0, t1)) return false;
+    int c0 = outcode(x0, y0);
+    int c1 = outcode(x1, y1);
 
-    if (t1 < 1.0f) {
-        x2 = x1 + static_cast<int>(std::round(t1 * dx));
-        y2 = y1 + static_cast<int>(std::round(t1 * dy));
+    while (true) {
+        if (!(c0 | c1)) {
+            return true;
+        }
+        if (c0 & c1) {
+            return false;
+        }
+
+        const int out = c0 ? c0 : c1;
+
+        double x = 0.0;
+        double y = 0.0;
+
+        if (out & TOP) {
+            y = ymax;
+            x = x0 + (x1 - x0) * static_cast<double>(ymax - y0) / (y1 - y0);
+        } else if (out & BOTTOM) {
+            y = ymin;
+            x = x0 + (x1 - x0) * static_cast<double>(ymin - y0) / (y1 - y0);
+        } else if (out & RIGHT) {
+            x = xmax;
+            y = y0 + (y1 - y0) * static_cast<double>(xmax - x0) / (x1 - x0);
+        } else { // LEFT
+            x = xmin;
+            y = y0 + (y1 - y0) * static_cast<double>(xmin - x0) / (x1 - x0);
+        }
+
+        if (out == c0) {
+            x0 = std::clamp(static_cast<int>(std::lround(x)), xmin, xmax);
+            y0 = std::clamp(static_cast<int>(std::lround(y)), ymin, ymax);
+            c0 = outcode(x0, y0);
+        } else {
+            x1 = std::clamp(static_cast<int>(std::lround(x)), xmin, xmax);
+            y1 = std::clamp(static_cast<int>(std::lround(y)), ymin, ymax);
+            c1 = outcode(x1, y1);
+        }
     }
-    if (t0 > 0.0f) {
-        x1 = x1 + static_cast<int>(std::round(t0 * dx));
-        y1 = y1 + static_cast<int>(std::round(t0 * dy));
-    }
-    return true;
+}
+
+static bool is_point_outside(int x, int y, int width, int height) {
+    return x < 0 || y < 0 || x >= width || y >= height;
 }
 
 template<uint channels>
@@ -155,11 +195,24 @@ static void draw_line(ImageData& image, int x1, int y1, int x2, int y2, const gl
     uint width = image.getWidth();
     uint height = image.getHeight();
 
+    glm::ivec4 init {x1, y1, x2, y2};
+
     if ((x1 < 0 || x1 >= width || x2 < 0 || x2 >= width ||
         y1 < 0 || y1 >= height || y2 < 0 || y2 >= height) &&
         !clip_line(x1, y1, x2, y2, width, height)) {
         return;
     }
+    // spam info for bug report
+    if (is_point_outside(x1, y1, width, height) || is_point_outside(x2, y2, width, height)) {
+        logger.warning() << "clip_line fault: [" << init.x << ", " << init.y
+                         << "] - [" << init.z << ", " << init.w << "] --> ["
+                         << x1 << ", " << y1 << "] - [" << x2 << ", " << y2
+                         << "]";
+        x1 = glm::clamp(x1, 0, static_cast<int>(width) - 1);
+        y1 = glm::clamp(y1, 0, static_cast<int>(height) - 1);
+        x2 = glm::clamp(x2, 0, static_cast<int>(width) - 1);
+        y2 = glm::clamp(y2, 0, static_cast<int>(height) - 1);
+    }
     
     int dx = std::abs(x2 - x1);
     int dy = -std::abs(y2 - y1);

src/logic/scripting/lua/usertypes/lua_type_canvas.cpp

@@ -81,16 +81,17 @@ union RGBA {
     uint8_t arr[4];
     uint32_t rgba;
 };
+static_assert(sizeof(RGBA) == 4);
 
-static RGBA* get_at(const ImageData& data, uint index) {
-    if (index >= data.getWidth() * data.getHeight()) {
-        return nullptr;
-    }
+static RGBA* get_at(const ImageData& data, size_t index) {
     return reinterpret_cast<RGBA*>(data.getData() + index * sizeof(RGBA));
 }
 
 static RGBA* get_at(const ImageData& data, uint x, uint y) {
-    return get_at(data, y * data.getWidth() + x);
+    if (x >= data.getWidth() || y >= data.getHeight()) {
+        return nullptr;
+    }
+    return get_at(data, static_cast<size_t>(y) * data.getWidth() + x);
 }
 
 static RGBA* get_at(State* L, uint x, uint y) {