KlassischeKeplerKriege/game/renderer_polygon_3d/particle_batch.cpp

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#include "particle_batch.hpp"
#include <iostream>
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// TODO: use VAO's as soon as this is working
int getDivisorForIndex(size_t index)
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{
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// 0 or 1?
return (index == 0) ? 0 : 3;
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}
namespace endofthejedi {
ParticleBatch::ParticleBatch(size_t id, size_t numParticles, float particleSize, float halfAge)
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: m_id(id)
, m_numParticles(numParticles)
, m_particleRadius(particleSize)
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, m_age(0.0)
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, m_halfAge(halfAge)
// XXX this is used in some places in the shader.
// set it via uniform too
, m_maxNumHalfAges(5.0)
, m_maxVelocity(1.0)
, m_center(glm::vec3(0.0f, 0.0f, 0.0f))
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// 2d quad drawn as a triangle fan.
//
// TODO
// it is transformed before uploading so it looks at the camera
, m_data_geometry({
0.5f, -0.5f,
0.5f, 0.5f,
-0.5f, 0.5f,
-0.5f, -0.5f})
{
m_num_vertex_buffers = 4;
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//std::cout<<"[ParticleBatch] create for " << numParticles << " num particles" << std::endl;
m_attr_locations.resize(m_num_vertex_buffers);
m_data_vbos.resize(m_num_vertex_buffers);
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m_data_position.resize(m_numParticles);
m_data_velocity.resize(m_numParticles);
m_data_max_distance.resize(m_numParticles);
for (size_t i=0; i<m_num_vertex_buffers; i++) {
m_attr_locations[i] = -1;
m_data_vbos[i] = 0;
}
}
ParticleBatch::~ParticleBatch()
{
// TODO: find out if stuff must be deallocated
glDeleteBuffers(m_num_vertex_buffers, m_data_vbos.data());
}
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void ParticleBatch::setup(Shader *shader)
{
static const char *names[] = {
"in_geometry",
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"in_position",
"in_velocity",
"in_maxDist"
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};
for (size_t i=0; i<m_num_vertex_buffers; i++) {
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const char *name = names[i];
GLint loc = glGetAttribLocation(shader->program(), name);
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m_attr_locations[i] = loc;
//std::cout<<"attr location for " << name << " (#" << i << ") is " << loc << std::endl;
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}
}
void ParticleBatch::setCenter(const glm::vec3 &center)
{
m_center = center;
}
void ParticleBatch::setMaxVelocity(float maxVelocity)
{
m_maxVelocity = maxVelocity;
}
void ParticleBatch::setParticle(size_t index, const glm::vec3 &p, const glm::vec3 &v, float maxDist)
{
if (index >= m_numParticles) {
return;
}
//std::cout<<"[ParticleBatch] setParticle " << index << std::endl;
m_data_position[index] = p;
m_data_velocity[index] = v;
m_data_max_distance[index] = maxDist;
}
void ParticleBatch::bind()
{
//std::cout<<"[ParticleBatch] bind" << std::endl;
for (size_t i=0; i<m_num_vertex_buffers; i++) {
//std::cout<<"vbo #" << i << ": " << m_data_vbos[i] << std::endl;
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glEnableVertexAttribArray(m_attr_locations[i]);
glBindBuffer(GL_ARRAY_BUFFER, m_data_vbos[i]);
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glVertexAttribDivisor(m_attr_locations[i], getDivisorForIndex(i));
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// TODO: i or index? at first argument?
glVertexAttribPointer(
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m_attr_locations[i],
dataSizeForIndex(i),
GL_FLOAT, // Data is floating point type
GL_FALSE, // No fixed point scaling
0, // stride: no
NULL); // No offset
}
}
void ParticleBatch::upload()
{
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//std::cout<<"[ParticleBatch] upload to vbo's " << std::endl;
glGenBuffers(m_num_vertex_buffers, m_data_vbos.data()); // Generate buffer
for (size_t i=0; i<m_num_vertex_buffers; i++) {
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size_t bufferDataSize = dataSizeForIndex(i) * m_numParticles * sizeof(float);
glEnableVertexAttribArray(i);
glBindBuffer(GL_ARRAY_BUFFER, m_data_vbos[i]);
// fill buffer with the loaded mesh position data
glBufferData(
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GL_ARRAY_BUFFER, // Buffer target
bufferDataSize, // Buffer data size
dataSourceForIndex(i), // Buffer data pointer
GL_STATIC_DRAW); // Usage - Data never changes;
}
}
void ParticleBatch::render(Shader *shader)
{
//std::cout<<"[ParticleBatch] render " << std::endl;
glUniform1f(shader->location("age"), m_age);
glUniform1f(shader->location("maxVelocity"), m_maxVelocity);
glUniform1f(shader->location("halfAge"), m_halfAge);
glUniform1f(shader->location("size"), m_particleRadius);
glUniform3f(shader->location("explCenter"), m_center.x, m_center.y, m_center.z);
bind();
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//glDrawArrays(GL_TRIANGLE_FAN, 0, 4*m_numParticles);
//glDrawArraysInstanced( GLenum mode, GLint first, GLsizei count, GLsizei primcount);
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// XXX the 3 is a magical number.
// I dont know why this works
// without it, it will render 1/3 of the particles
glDrawArraysInstanced(GL_TRIANGLE_FAN, 0, 4, 3*m_numParticles);
#if 0
glBegin(GL_QUADS);
for (size_t index=0; index<m_numParticles; index++) {
for (size_t i=0; i<4; i++) {
glm::vec2 p = m_data_position[index] + triangles[i];
//glColor3f(1.0, 0.0, 0.0);
glVertex2f(p.x, p.y);
}
}
glEnd();
#endif
}
size_t ParticleBatch::dataSizeForIndex(size_t index)
{
switch(index) {
case 0:
return 2;
case 1:
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case 2:
return 3;
case 3:
return 1;
default:
std::cerr << "dataSizeForIndex() bad" << std::endl;
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exit(-1);
}
}
void *ParticleBatch::dataSourceForIndex(size_t index)
{
switch(index) {
case 0: return (void *) m_data_geometry.data();
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case 1: return (void *) m_data_position.data();
case 2: return (void *) m_data_velocity.data();
case 3: return (void *) m_data_max_distance.data();
default:
std::cerr << "dataSourceForIndex() bad" << std::endl;
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exit(-1);
}
}
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void ParticleBatch::tick(float dt)
{
m_age += dt;
}
bool ParticleBatch::done() const
{
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return m_age >= m_maxNumHalfAges*m_halfAge;
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}
}