From 7228b2e1a2d0a8399facce3493d71a3569d250d5 Mon Sep 17 00:00:00 2001
From: mattkae <mattkae@protonmail.com>
Date: Fri, 23 Dec 2022 12:47:10 -0500
Subject: Improved the makefile considerably

---
 themes/src/Snowflake.cpp | 135 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 135 insertions(+)
 create mode 100644 themes/src/Snowflake.cpp

(limited to 'themes/src/Snowflake.cpp')

diff --git a/themes/src/Snowflake.cpp b/themes/src/Snowflake.cpp
new file mode 100644
index 0000000..7cab8b3
--- /dev/null
+++ b/themes/src/Snowflake.cpp
@@ -0,0 +1,135 @@
+#include "Snowflake.h"
+#include "Renderer2d.h"
+#include "mathlib.h"
+#include "list.h"
+#include <cstdio>
+
+const Vector4 snowColor = Vector4(1.0, 0.98, 0.98, 1);
+
+inline void generateSnowflakeShape(matte::List<Vertex2D>* vertices, i32 numArms, f32 radius, f32 innerRadius) {
+	f32 dx = ((2 * PI) / numArms) / 3.0;
+	for (i32 centerIdx = 0; centerIdx < (3 * numArms); centerIdx+=3) {
+	    f32 degreeStart = dx * centerIdx;
+		f32 degreeEnd = dx * (centerIdx + 1);
+
+		f32 cosStart = cosf(degreeStart);
+		f32 cosEnd = cosf(degreeEnd);
+
+		f32 sinStart = sinf(degreeStart);
+		f32 sinEnd = sinf(degreeEnd);
+
+		Vector2 leftEnd = Vector2(radius * cosStart, radius * sinStart);
+		Vector2 rightEnd = Vector2(radius * cosEnd, radius * sinEnd);
+		Vector2 diff = (rightEnd - leftEnd) / 2.0;
+		Vector2 leftStart = Vector2(-diff.x, -diff.y) + Vector2(innerRadius * cosStart, innerRadius * sinStart);
+		Vector2 rightStart = diff + Vector2(innerRadius * cosEnd, innerRadius * sinEnd);
+
+		vertices->add({ leftStart, snowColor, Mat4x4() });
+		vertices->add({ leftEnd, snowColor, Mat4x4() });
+		vertices->add({ rightEnd, snowColor, Mat4x4() });
+		vertices->add({ rightEnd, snowColor, Mat4x4() });
+		vertices->add({ rightStart, snowColor, Mat4x4() });
+		vertices->add({ leftStart, snowColor, Mat4x4() });
+	}
+}
+
+inline void initFlake(SnowflakeParticleRenderer* renderer, SnowflakeUpdateData* ud) {
+	ud->vtxIdx = renderer->vertices.numElements;
+	generateSnowflakeShape(&renderer->vertices, randomIntBetween(4, 16), randomFloatBetween(8.f, 16.f), randomFloatBetween(2.f, 6.f));
+	ud->numVertices = renderer->vertices.numElements - ud->vtxIdx;
+	ud->velocity = Vector2(randomFloatBetween(-10, 10), randomFloatBetween(-100, -85));
+	ud->position = Vector2(randomFloatBetween(0, renderer->xMax), randomFloatBetween(renderer->yMax, -renderer->yMax));
+}
+
+void SnowflakeParticleRenderer::load(SnowflakeLoadParameters params, Renderer2d* renderer) {
+	numSnowflakes = params.numSnowflakes;
+
+	updateData = new SnowflakeUpdateData[params.numSnowflakes];
+
+	xMax = static_cast<f32>(renderer->context->width);
+    yMax = static_cast<f32>(renderer->context->height);
+
+    vertices.deallocate();
+    vertices.growDynamically = true;
+    
+	// Initialize each snow flake with its shape
+	for (i32 s = 0; s < numSnowflakes; s++) {
+		auto ud = &updateData[s];
+	    initFlake(this, ud);
+	}
+
+	useShader(renderer->shader);
+
+    glGenVertexArrays(1, &vao);
+    glBindVertexArray(vao);
+
+    glGenBuffers(1, &vbo);
+    glBindBuffer(GL_ARRAY_BUFFER, vbo);
+    glBufferData(GL_ARRAY_BUFFER, vertices.numElements * sizeof(Vertex2D), &vertices.data[0], GL_DYNAMIC_DRAW);
+
+    glEnableVertexAttribArray(renderer->attributes.position);
+    glVertexAttribPointer(renderer->attributes.position, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex2D), (GLvoid *)0);
+
+    glEnableVertexAttribArray(renderer->attributes.color);
+    glVertexAttribPointer(renderer->attributes.color, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex2D), (GLvoid *)offsetof(Vertex2D, color));
+
+	for (i32 idx = 0; idx < 4; idx++) {
+		i32 offset = (4 * sizeof(f32)) * idx;
+		glEnableVertexAttribArray(renderer->attributes.vMatrix + idx);
+		glVertexAttribPointer(renderer->attributes.vMatrix + idx,
+							  4,
+							  GL_FLOAT,
+							  GL_FALSE,
+							  sizeof(Vertex2D),
+							  (GLvoid *)(offsetof(Vertex2D, vMatrix) + offset));
+		//glVertexAttribDivisor(renderer->attributes.vMatrix + idx, 1);
+	}
+
+    glBindBuffer(GL_ARRAY_BUFFER, 0);
+    glBindVertexArray(0);
+}
+
+inline void updateFlake(SnowflakeParticleRenderer* renderer, SnowflakeUpdateData* ud, i32 s, f32 dtSeconds, bool addWind) {
+	if (addWind) ud->velocity += renderer->windSpeed;		
+	ud->position += ud->velocity * dtSeconds;
+
+	Mat4x4 m = Mat4x4().translateByVec2(ud->position);
+	for (i32 v = ud->vtxIdx; v < (ud->vtxIdx + ud->numVertices); v++) {
+		renderer->vertices.data[v].vMatrix = m;
+	}
+}
+
+void SnowflakeParticleRenderer::update(f32 dtSeconds) {
+	bool addWind = false;
+	timeUntilNextWindSeconds -= dtSeconds;
+	if (timeUntilNextWindSeconds < 0) {
+		timeUntilNextWindSeconds = windIntervalSeconds;
+		windSpeed = Vector2(randomFloatBetween(-10, 10), randomFloatBetween(-10, 0));
+		addWind = true;
+	}
+
+    for (i32 s = 0; s < numSnowflakes; s++) {
+        SnowflakeUpdateData* ud = &updateData[s];
+        updateFlake(this, ud, s, dtSeconds, addWind);
+    }
+}
+
+void SnowflakeParticleRenderer::render(Renderer2d* renderer) {
+	setShaderMat4(renderer->uniforms.model, model);
+
+    glBindBuffer(GL_ARRAY_BUFFER, vbo);
+    glBufferSubData(GL_ARRAY_BUFFER, 0, vertices.numElements * sizeof(Vertex2D), &vertices.data[0]);
+
+    glBindVertexArray(vao);
+    glDrawArrays(GL_TRIANGLES, 0, vertices.numElements);
+    glBindVertexArray(0);
+}
+
+void SnowflakeParticleRenderer::unload() {
+	glDeleteVertexArrays(1, &vao);
+    glDeleteBuffers(1, &vbo);
+	vao = 0;
+	vbo = 0;
+	vertices.deallocate();
+	delete [] updateData;
+}
-- 
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