Shader Demo: Factor out animated rectangle definitions

2 files changed, 84 insertions, 44 deletions

diff --git a/examples/pugl_gl3_demo.c b/examples/pugl_gl3_demo.c
index a2d6094..f43592d 100644
--- a/examples/pugl_gl3_demo.c
+++ b/examples/pugl_gl3_demo.c
@@ -35,6 +35,7 @@
 */
 
 #include "demo_utils.h"
+#include "rects.h"
 #include "shader_utils.h"
 #include "test/test_utils.h"
 
@@ -44,7 +45,6 @@
 #include "pugl/pugl.h"
 #include "pugl/pugl_gl.h"
 
-#include <math.h>
 #include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -55,24 +55,6 @@ static const int defaultHeight = 512;
 
 typedef struct
 {
-	float pos[2];
-	float size[2];
-	float fillColor[4];
-} Rect;
-
-// clang-format off
-static const GLfloat rectVertices[] = {
-	0.0f, 0.0f, // TL
-	1.0f, 0.0f, // TR
-	0.0f, 1.0f, // BL
-	1.0f, 1.0f, // BR
-};
-// clang-format on
-
-static const GLuint rectIndices[4] = {0, 1, 2, 3};
-
-typedef struct
-{
 	PuglTestOptions opts;
 	PuglWorld*      world;
 	PuglView*       view;
@@ -134,19 +116,7 @@ onExpose(PuglView* view)
 	glUniformMatrix4fv(app->u_projection, 1, GL_FALSE, (const GLfloat*)&proj);
 
 	for (size_t i = 0; i < app->numRects; ++i) {
-		Rect*       rect      = &app->rects[i];
-		const float normal    = i / (float)app->numRects;
-		const float offset[2] = {normal * 128.0f, normal * 128.0f};
-
-		// Move rect around in an arbitrary way that looks cool
-		rect->pos[0] = (width - rect->size[0] + offset[0]) *
-		               (sinf((float)time * rect->size[0] / 64.0f + normal) +
-		                1.0f) /
-		               2.0f;
-		rect->pos[1] = (height - rect->size[1] + offset[1]) *
-		               (cosf((float)time * rect->size[1] / 64.0f + normal) +
-		                1.0f) /
-		               2.0f;
+		moveRect(&app->rects[i], i, app->numRects, width, height, time);
 	}
 
 	glBufferSubData(GL_ARRAY_BUFFER,
@@ -199,20 +169,9 @@ onEvent(PuglView* view, const PuglEvent* event)
 static Rect*
 makeRects(const size_t numRects)
 {
-	const float minSize  = (float)defaultWidth / 64.0f;
-	const float maxSize  = (float)defaultWidth / 6.0f;
-	const float boxAlpha = 0.2f;
-
 	Rect* rects = (Rect*)calloc(numRects, sizeof(Rect));
 	for (size_t i = 0; i < numRects; ++i) {
-		const float s = (sinf((float)i) / 2.0f + 0.5f);
-		const float c = (cosf((float)i) / 2.0f + 0.5f);
-
-		rects[i].size[0]      = minSize + s * maxSize;
-		rects[i].size[1]      = minSize + c * maxSize;
-		rects[i].fillColor[1] = s / 2.0f + 0.25f;
-		rects[i].fillColor[2] = c / 2.0f + 0.25f;
-		rects[i].fillColor[3] = boxAlpha;
+		rects[i] = makeRect(i, (float)defaultWidth);
 	}
 
 	return rects;
diff --git a/examples/rects.h b/examples/rects.h
new file mode 100644
index 0000000..aca0256
--- /dev/null
+++ b/examples/rects.h
@@ -0,0 +1,81 @@
+/*
+  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;
+}