1 files changed, 159 insertions, 0 deletions
diff --git a/themes/TreeShape.cpp b/themes/TreeShape.cpp
new file mode 100644
index 0000000..b3d5c84
--- /dev/null
+++ b/themes/TreeShape.cpp
@@ -0,0 +1,159 @@
+#include "TreeShape.h"
+#include "mathlib.h"
+#include <cstdio>
+#include <cstdlib>
+
+
+void TreeBranchLoadData::fillVertices(Renderer2dVertex* vertices, int branchTier) {
+    bottomLeft = Vector2 { position.x - width / 2.f, position.y }.rotateAbout(rotation, position);
+    bottomRight = Vector2 { position.x + width / 2.f, position.y }.rotateAbout(rotation, position);
+    topLeft = (Vector2 { position.x - width / 2.f, position.y + height }).rotateAbout(rotation, position);
+    topRight = (Vector2 { position.x + width / 2.f, position.y + height }).rotateAbout(rotation, position);
+
+    topMidpoint = topLeft + (topRight - topLeft) / 2.f;
+
+    vertices[0] = { bottomLeft, color, Vector2(1, 1) };
+    vertices[1] = { bottomRight, color, Vector2(1, 1) };
+    vertices[2] = { topLeft, color, Vector2(1, 1) };
+    vertices[3] = { topLeft, color, Vector2(1, 1) };
+    vertices[4] = { topRight, color, Vector2(1, 1) };
+    vertices[5] = { bottomRight, color, Vector2(1, 1) };
+};
+
+inline float32 randomFloatBetween(float32 min, float32 max) {
+    float32 random = static_cast<float32>(rand()) / static_cast<float32>(RAND_MAX);
+    return (max - min) * random + min;
+}
+
+void TreeShape::load(Renderer2d* renderer) {
+    TreeLoadData ld;
+
+    numBranches = pow(ld.divisionsPerBranch, ld.numBranchLevels + 1);
+    numVertices = 6 * numBranches;
+
+    TreeBranchLoadData* generationData = new TreeBranchLoadData[numBranches];
+    updateData = new TreeBranchUpdateData[numBranches];
+    vertices = new Renderer2dVertex[numVertices];
+
+    int32 branchIndex = 0;
+    createBranch(&ld, generationData, numBranches, &branchIndex, 0, ld.trunkWidth, ld.trunkHeight, Vector2 { 400.f, 50.f }, 0, vertices);
+
+    useShader(renderer->shader);
+
+    glGenVertexArrays(1, &vao);
+    glBindVertexArray(vao);
+
+    glGenBuffers(1, &vbo);
+    glBindBuffer(GL_ARRAY_BUFFER, vbo);
+    glBufferData(GL_ARRAY_BUFFER, numVertices * sizeof(Renderer2dVertex), &vertices[0], GL_DYNAMIC_DRAW);
+
+    glEnableVertexAttribArray(renderer->attributes.position);
+    glVertexAttribPointer(renderer->attributes.position, 2, GL_FLOAT, GL_FALSE, sizeof(Renderer2dVertex), (GLvoid *)0);
+
+    glEnableVertexAttribArray(renderer->attributes.color);
+    glVertexAttribPointer(renderer->attributes.color, 4, GL_FLOAT, GL_FALSE, sizeof(Renderer2dVertex), (GLvoid *)offsetof(Renderer2dVertex, color));
+
+    glEnableVertexAttribArray(renderer->attributes.scale);
+	glVertexAttribPointer(renderer->attributes.scale, 2, GL_FLOAT, GL_FALSE, sizeof(Renderer2dVertex), (GLvoid *)offsetof(Renderer2dVertex, scale));
+
+    glBindBuffer(GL_ARRAY_BUFFER, 0);
+    glBindVertexArray(0);
+
+    delete [] generationData;
+}
+
+const float32 ninetyDegreeRotation = PI / 2.f;
+
+void TreeShape::createBranch(TreeLoadData* ld, TreeBranchLoadData* generationData, int32 numBranches, int32* branchIndex, int32 branchLevel, float32 width, float32 height, Vector2 position, float32 rotation, Renderer2dVertex* vertices) {
+    TreeBranchLoadData* branchLoadData = &generationData[*branchIndex];
+    branchLoadData->width = width;
+    branchLoadData->height = height;
+    branchLoadData->position = position;
+    branchLoadData->rotation = rotation;
+    branchLoadData->fillVertices(&vertices[(*branchIndex) * 6], branchLevel);
+
+    TreeBranchUpdateData* branchUpdateData = &updateData[*branchIndex];
+    branchUpdateData->tier = branchLevel;
+    branchUpdateData->randomOffset = randomFloatBetween(-1.f, 1.f);
+
+    if (branchLevel == ld->numBranchLevels) {
+        return;
+    }
+    
+    for (int division = 0; division < ld->divisionsPerBranch; division++) {
+        // Weight between [0, 1]
+        float weight = static_cast<float32>(division) / static_cast<float32>(ld->divisionsPerBranch - 1);
+        
+        // Normalize the weight between [-1, 1]
+        float32 normalizedWeight = (0.5f - (weight)) * 2.f;
+
+        // We want a rotation that takes the current rotation of the branch, and averages it between the two branches.
+        float32 branchRotationAmount = randomFloatBetween(PI / 8.f, PI / 3.f);
+        float32 branchRotation =  branchLoadData->rotation + (normalizedWeight * branchRotationAmount);
+        
+        // Since trees are taller vertically, we will find a normalized value that describes how far the direction is from
+        // being horizontal. If it is closer to 1, we will make the branch taller on average.
+        float32 verticalHeightScaler = (fabs(fabs(branchRotation) - ninetyDegreeRotation) / ninetyDegreeRotation) * 0.1;
+        float32 branchWidth = width * randomFloatBetween(ld->trunkWidthScalerMin, ld->trunkWidthScalerMax);
+        float32 branchHeight = height * randomFloatBetween(ld->trunkHeightScalerMin + verticalHeightScaler, ld->trunkHeightScalerMax + verticalHeightScaler);
+
+
+        // We want the branch to start within the previous branch, so we drop it down into it based off of the rotation.
+        Vector2 branchOffsetVertical = Vector2{ 0, branchWidth }.rotate(branchRotation);
+        
+        Vector2 branchPosition = branchLoadData->topLeft + ((branchLoadData->topRight - branchLoadData->topLeft) * weight)  - branchOffsetVertical; // Position of branch along the top of the parent branch
+        
+        (*branchIndex)++;
+        createBranch(ld, generationData, numBranches, branchIndex, branchLevel + 1, branchWidth, branchHeight, branchPosition, branchRotation, vertices);
+    }
+}
+
+void TreeShape::update(float32 dtSeconds) {
+    timeElapsedSeconds += dtSeconds;
+
+    for (int32 bIdx = 0; bIdx < numBranches; bIdx++) {
+        TreeBranchUpdateData* branchUpdataData = &updateData[bIdx];
+
+        // Fade in simulation. We fade in based on the tier.
+        float32 animationStart = (branchUpdataData->tier * animateStaggerPerTier);
+        float32 animationEnd = animationStart + animateTimePerTier;
+
+        float32 alpha = 0.f;
+        if (timeElapsedSeconds < animationStart) {
+            alpha = 0.f;
+        }
+        else if (timeElapsedSeconds > animationEnd) {
+            alpha = 1.f;
+        }
+        else {
+            alpha = (1.f - (animationEnd - timeElapsedSeconds)) / animateTimePerTier;
+        }
+
+        int startParentIndex = bIdx * 6;
+        for (int32 sIdx = 0; sIdx < 6; sIdx++) {
+            int32 vidx = startParentIndex + sIdx;
+            vertices[vidx].color.w = alpha;
+
+            // Wind simualtion
+            vertices[vidx].position.x += ((branchUpdataData->randomOffset + branchUpdataData->tier) * 0.01f) * sinf(timeElapsedSeconds);
+        }
+    }
+}
+	
+void TreeShape::render(Renderer2d* renderer) {
+    setShaderMat4(renderer->uniforms.model, model);
+
+    glBindBuffer(GL_ARRAY_BUFFER, vbo);
+    glBufferSubData(GL_ARRAY_BUFFER, 0, numVertices * sizeof(Renderer2dVertex), &vertices[0]);
+
+    glBindVertexArray(vao);
+    glDrawArrays(GL_TRIANGLES, 0, numVertices);
+    glBindVertexArray(0);
+}
+	
+void TreeShape::unload() {
+    glDeleteVertexArrays(1, &vao);
+    glDeleteBuffers(1, &vbo);
+    delete[] vertices;
+    delete [] updateData;
+}