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authorDavid Robillard <d@drobilla.net>2020-04-04 13:36:44 +0200
committerDavid Robillard <d@drobilla.net>2020-04-04 13:36:44 +0200
commitac3036fd7343ce71377fbfecafd8ba672372a5b9 (patch)
tree236fae5a87dd62871d86c2e11904c220f879f213 /examples/rects.h
parent84222d61aaf9416cca0a0eb695e20623441b698b (diff)
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Shader Demo: Factor out animated rectangle definitions
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+/*
+ Copyright 2019-2020 David Robillard <http://drobilla.net>
+
+ Permission to use, copy, modify, and/or distribute this software for any
+ purpose with or without fee is hereby granted, provided that the above
+ copyright notice and this permission notice appear in all copies.
+
+ THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+/**
+ @file rects.h Utilities for rectangle animation demos.
+
+ This file contains common definitions for demos that show an animation of
+ many 2D rectangles.
+*/
+
+#include <math.h>
+#include <stddef.h>
+
+typedef float vec2[2];
+
+typedef struct {
+ float pos[2];
+ float size[2];
+ float fillColor[4];
+} Rect;
+
+static const vec2 rectVertices[] = {
+ {0.0f, 0.0f}, // TL
+ {1.0f, 0.0f}, // TR
+ {0.0f, 1.0f}, // BL
+ {1.0f, 1.0f} // BR
+};
+
+static const unsigned rectIndices[4] = {0, 1, 2, 3};
+
+/// Make a new rectangle with the given index (each is slightly different)
+static inline Rect
+makeRect(const size_t index, const float frameWidth)
+{
+ static const float alpha = 0.3f;
+ const float minSize = frameWidth / 64.0f;
+ const float maxSize = frameWidth / 6.0f;
+ const float s = (sinf((float)index) / 2.0f + 0.5f);
+ const float c = (cosf((float)index) / 2.0f + 0.5f);
+
+ const Rect rect = {
+ {0.0f, 0.0f}, // Position is set later during expose
+ {minSize + s * maxSize, minSize + c * maxSize},
+ {0.0f, s / 2.0f + 0.25f, c / 2.0f + 0.25f, alpha},
+ };
+
+ return rect;
+}
+
+/// Move `rect` with the given index around in an arbitrary way that looks cool
+static inline void
+moveRect(Rect* const rect,
+ const size_t index,
+ const size_t numRects,
+ const float frameWidth,
+ const float frameHeight,
+ const double time)
+{
+ const float normal = index / (float)numRects;
+ const float offset[2] = {normal * 128.0f, normal * 128.0f};
+
+ rect->pos[0] = (frameWidth - rect->size[0] + offset[0]) *
+ (sinf((float)time * rect->size[0] / 64.0f + normal) + 1.0f) /
+ 2.0f;
+ rect->pos[1] = (frameHeight - rect->size[1] + offset[1]) *
+ (cosf((float)time * rect->size[1] / 64.0f + normal) + 1.0f) /
+ 2.0f;
+}