Demo: integrated a reworked demo from @bdero (TODO: default parent window size missing)
https://gist.github.com/bdero/987a959c33b0d9dc8ab04bc5aeecb50c
diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index 234daec..f145d51 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt
@@ -1660,6 +1660,9 @@
- Style: Changed default style.WindowRounding value to 0.0f (matches default for multi-viewports).
- Style: Reduced the size of the resizing grip, made alpha less prominent.
- Style: Classic: Increase the default alpha value of WindowBg to be closer to other styles.
+- Demo: Added a fancy "particle text" demo in Examples->Custom Rendering. [@bdero]
+ Originally done as a 1024 bytes source, as part of the "ImDrawList coding party" challenge:
+ https://github.com/ocornut/imgui/issues/3606
- Demo: Clarify usage of right-aligned items in Demo>Layout>Widgets Width.
- Backends: OpenGL3: Use glGetString(GL_VERSION) query instead of glGetIntegerv(GL_MAJOR_VERSION, ...)
when the later returns zero (e.g. Desktop GL 2.x). (#3530) [@xndcn]
diff --git a/imgui_demo.cpp b/imgui_demo.cpp
index 431cd4c..7a0c3c4 100644
--- a/imgui_demo.cpp
+++ b/imgui_demo.cpp
@@ -7593,6 +7593,79 @@
// [SECTION] Example App: Custom Rendering using ImDrawList API / ShowExampleAppCustomRendering()
//-----------------------------------------------------------------------------
+// Mini "Particle Text" demo by Brandon DeRosier
+// Originally done as a 1024 bytes source, as part of the "ImDrawList coding party" challenge:
+// - https://github.com/ocornut/imgui/issues/3606#issuecomment-734636054
+// - https://twitter.com/algebrandon/status/1332182010593304576
+// This is a fun thing to inspire people to see the potential of using ImDrawList for custom drawing.
+// However, the very dense coding-style is not something to be inspired of :) don't do this at home!
+static void ShowFxParticleText(ImDrawList* draw_list, ImVec2 p0, ImVec2 p1, float time)
+{
+ // The base diameter (and distance apart) all of the circles should be on the grid.
+ // The actual diameter is inflated a bit from this value so that the circles smoosh together.
+ const float diameter = 11.0f;
+ const float scale = (p1.x - p0.x) / 400.0f;
+
+ // This packed array contains a 17x13 grid (221-bit) spelling the word "DEAR IMGUI". Last 3 bits are unused (hence the -3 in the loop below).
+ const unsigned int GRID[] = { 0xD9000080, 0x750A2B18, 0xDC2A2A17, 0x0200025D, 0x5AB1E800, 0x26EAB555, 0x01800100 };
+
+ // Storage for a rotating circle (we use the index for sorting and for computing the color)
+ struct GridCircle { float x, y, z; int index; };
+ GridCircle circles[221];
+
+ // Helper functions
+ struct f
+ {
+ // This is a S-curve function `1/(1+e^-t)`, but with a range of 0 to 2 PI
+ // because this demo happens to only use it for computing rotations.
+ // See also: https://en.wikipedia.org/wiki/Sigmoid_function
+ static float Sigmoid(float T) { return 1.f / (1 + expf(-(T))) * 3.141592f * 2.0f; }
+
+ // This is a Sine function with an exponentially decaying magnitude `sin(t)`.
+ // The intended domain is 0 to ~5, and the range is -1 to 1.
+ static float Bounce(float T) { return sinf((T) * 3.0f) * expf(-(T)); }
+
+ // 2D rotation formula. This demo uses Euler angles, and so this formula is used
+ // three times (once for each basis axis) when computing the position of each circle.
+ // See also: https://en.wikipedia.org/wiki/Rotation_matrix
+ static void Rotate(float& u, float& v, float r) { float U = u; u = cosf(r) * u - sinf(r) * v; v = sinf(r) * U + cosf(r) * v; }
+
+ // Sorting function so that circles with higher Z values (which are further away from the camera) are given lower order
+ static int IMGUI_CDECL GridCircleCompareByZ(const void* a, const void* b) { return (((const GridCircle*)b)->z - ((const GridCircle*)a)->z > 0.0f) ? 1 : -1; }
+ };
+
+ // For each circle in the grid: rotate, calculate z and calculate x
+ const float loop_time = fmodf(time, 6.0f) * 10.0f;
+ for (int n = 3; n < 224; n++)
+ {
+ int index = (n - 3);
+ float x = (float)(index % 17) * diameter - 9.0f * diameter;
+ float y = (float)(index / 17) * diameter - 6.0f * diameter;
+ float z = 0.0f;
+ float distance = sqrtf(x * x + y * y) / 32.0f;
+ f::Rotate(x, y, f::Sigmoid(loop_time - 20 - distance) + cosf(time / 2) / 4); // Rotate on Z axis
+ f::Rotate(y, z, f::Sigmoid(loop_time - 4 - distance) + cosf(time / 3) / 4); // Rotate on X axis
+ f::Rotate(x, z, f::Sigmoid(loop_time - 12 - distance) + cosf(time / 7) / 4); // Rotate on Y axis
+
+ z -= (loop_time - distance > 28) ? f::Bounce((loop_time - 28 - distance) / 2) * 50 : 0;
+ z = (GRID[n / 32] & (1 << (n % 32))) ? z / 100.f + 1.f : 0.0f;
+
+ circles[index].x = p0.x + (p1.x - p0.x) * 0.5f + scale * x / z;
+ circles[index].y = p0.y + (p1.y - p0.y) * 0.5f + scale * y / z;
+ circles[index].z = z;
+ circles[index].index = index;
+ }
+
+ // Sort back-to-front, then draw
+ qsort(&circles[0], 221, sizeof(GridCircle), f::GridCircleCompareByZ);
+ for (GridCircle& c : circles)
+ if (c.z != 0.0f)
+ {
+ ImU32 col = IM_COL32(c.index > 102 ? 0 : 255, c.index < 102 ? 0 : 255, IM_CLAMP((int)(765 - c.z * 637), 0, 255), 255);
+ draw_list->AddCircleFilled(ImVec2(c.x, c.y), (diameter * 0.8f / c.z) * scale, col);
+ }
+}
+
// Demonstrate using the low-level ImDrawList to draw custom shapes.
static void ShowExampleAppCustomRendering(bool* p_open)
{
@@ -7610,6 +7683,26 @@
if (ImGui::BeginTabBar("##TabBar"))
{
+ if (ImGui::BeginTabItem("Fancy demo"))
+ {
+ // Mini "Particle Text" demo by Brandon DeRosier
+ // See ShowFxParticleText() for details!
+ static float time = 0.0f;
+ time = ImGui::IsWindowAppearing() ? 0.0f : time + ImGui::GetIO().DeltaTime;
+ float w = ImGui::GetContentRegionAvail().x;
+ float h = (float)(int)(w / 1.777f);
+ ImDrawList* draw_list = ImGui::GetWindowDrawList();
+ ImGui::InvisibleButton("canvas", ImVec2(w, h));
+ ImVec2 p0 = ImGui::GetItemRectMin();
+ ImVec2 p1 = ImGui::GetItemRectMax();
+ draw_list->PushClipRect(p0, p1, true);
+ draw_list->AddRectFilled(p0, p1, IM_COL32(0, 0, 0, 100));
+ ShowFxParticleText(draw_list, p0, p1, time);
+ draw_list->AddRect(p0, p1, IM_COL32(100, 100, 100, 100));
+ draw_list->PopClipRect();
+ ImGui::EndTabItem();
+ }
+
if (ImGui::BeginTabItem("Primitives"))
{
ImGui::PushItemWidth(-ImGui::GetFontSize() * 15);
