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#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;
}
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