feat: animation

sww/test/shapes.c

@@ -9,7 +9,7 @@
 #include "sww/util.h"
 #include "sww/window.h"
 
-#define MAX_SCENE 10
+#define MAX_SCENE 11
 
 #define TITLE "SWW Shapes"
 
@@ -128,6 +128,68 @@ void HideSphere(swwRenderer* o, int cx, int cy, float r, int alpha, int beta, in
     }
 }
 
+const uint32_t kDim = 512;
+const uint32_t kFrames = 48;
+
+static void Animation(swwRenderer* o)
+{
+    static uint32_t i = 0;
+    const uint32_t size = kDim * kDim * 4;
+
+    // A fading sphere
+    uint8_t alpha = 255;
+    if (i < kFrames / 2) {
+        alpha = (uint8_t)(255 * (i / ((float)kFrames / 2)));
+    } else {
+        alpha = (uint8_t)(255 * (((kFrames / 2) - (i - kFrames / 2)) / ((float)kFrames / 2)));
+    }
+
+    const int spherew = 60;
+    const int spherex = (kDim - spherew) / 2;
+    const int maxdist = (spherew / 2) * (spherew / 2);
+    for (int x = spherex; x < spherex + spherew; x++) {
+        for (int y = 20; y < 20 + spherew; y++) {
+            float distx = x - (spherex + (float)spherew / 2);
+            float disty = y - (20 + (float)spherew / 2);
+            float dist = distx * distx + disty * disty;
+
+            if (dist > maxdist)
+                continue;
+
+            const float fill = dist / maxdist;
+            const uint8_t grey = (uint8_t)(fill * 255);
+
+            uint8_t myalpha = alpha;
+            if (fill > 0.9)
+                myalpha *= (uint8_t)((1.0f - fill) * 10);
+
+            swwRenderer_DrawPixel(o, (Point2i){x, y}, Color_RGBA(grey, grey, grey, myalpha));
+        }
+    }
+
+    // A moving blob
+    const float pos = (i / (float)kFrames) * 2 - 0.5f;
+
+    const int xoffset = (int)(pos * kDim);
+    const int yoffset = 2 * kDim / 3;
+    const int w = kDim / 4;
+
+    for (int x = -w; x < w; x++) {
+        if (x + xoffset < 0 || x + xoffset >= (int)kDim)
+            continue;
+        for (int y = yoffset - w; y < yoffset + w; y++) {
+            const uint8_t grey = abs(y - yoffset);
+            swwRenderer_DrawPixel(o, (Point2i){x + xoffset, y}, Color_RGBA(grey, grey, grey, 127));
+        }
+    }
+
+    if (i < kFrames) {
+        ++i;
+    } else {
+        i = 0;
+    }
+}
+
 int main()
 {
     int w = 512, h = 512;
@@ -220,7 +282,10 @@ int main()
                 }
             }
         } break;
-        case 9:
+        case 9: {
+            Animation(ud.renderer);
+        } break;
+        case 10:
         default: {
             swwRenderer_DrawArc(ud.renderer, (Point2i){cw, ch}, 150, 30.f, 90.f,
                                 Color_RGB(0x00, 0x00, 0xff), 0);