粒子系統錯誤

Question

我可是從本教程中的粒子系統類工作Particles - Anton's OpenGL 4 Wiki - Dr Anton Gerdelan

代碼：

//Pixel Shader 

// shader to update a particle system based on a simple kinematics function 
#version 150 

in vec3 v; // initial velocity 
in float tZero; // start time 

uniform mat4 projViewModelMatrix; 

uniform vec3 emitterPos_wor; // emitter position in world coordinates 
uniform float T; // system time T in seconds 

out float opacity; 

void main() { 
// work out how many seconds into our particle's life-time we are (after its starting time) 
float t = T - tZero; 
vec3 p; 
// gradually make particle more transparent over its life-time 
opacity = 1 - (t/3) - 0.2; 

// particle stays put until it has reached its birth second 
if (t > 0) { 
// gravity 
vec3 a = vec3(0,-10,0); 
// this is a standard kinematics equation of motion with velocity (from VBO) and acceleration (gravity) 
p = emitterPos_wor + v * t + 0.5 * a * t * t; 
} else { 
p = emitterPos_wor; 
} 
gl_Position = projViewModelMatrix * vec4(p, 1); 
} 


// Vertex shader 

// shader to render simple particle system's points 
#version 150 

uniform sampler2D textureMap; // I used a texture for my particles 
out vec4 fragColour; 

uniform vec4 Color; 

in float opacity; 

void main() { 
vec4 texcol = texture2D(textureMap, gl_PointCoord); // using point uv coordinates which are pre-defined over the point 
fragColour = vec4(1-opacity,1-opacity,1-opacity,1-opacity) * texcol * Color; // bright blue! 
} 

/////// CPU 

bool ParticleSystem::init(vec3 Position){ 

std::vector<vec3> Velocidad; 
std::vector<float> Life; 

for (int i = 0; i < MAX_PARTICLES; i++) { 
Velocidad.push_back(vec3(0,-1,0)); 
} 

for (int i = 0; i < MAX_PARTICLES; i++) { 
Life.push_back(0.001f * (float)(i)); 
} 


glGenVertexArrays(1, &m_VAO); 
glBindVertexArray(m_VAO); 

glGenBuffers(ARRAY_SIZE_IN_ELEMENTS(m_Buffers), m_Buffers); 

glBindBuffer(GL_ARRAY_BUFFER, m_Buffers[VEL_VB]); 
glBufferData(GL_ARRAY_BUFFER, sizeof(Velocidad[0]) * Velocidad.size(), &Velocidad[0], GL_STATIC_DRAW); 
glEnableVertexAttribArray(0); 
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);  

glBindBuffer(GL_ARRAY_BUFFER, m_Buffers[LIF_VB]); 
glBufferData(GL_ARRAY_BUFFER, sizeof(Life[0]) * Life.size(), &Life[0], GL_STATIC_DRAW); 
glEnableVertexAttribArray(1); 
glVertexAttribPointer(1, 1, GL_FLOAT, GL_FALSE, 0, 0);  

glBindVertexArray(0); 

return true; 
} 

/////////////////// FINAL RENDER 

bool ParticleSystem::render(){ 

glActiveTexture(GL_TEXTURE0); 
glBindTexture(GL_TEXTURE_2D,ModeloOrtho.getTextureFromID(24)); 

glTexEnvi(GL_POINT_SPRITE, GL_COORD_REPLACE, GL_TRUE); 
glEnable(GL_POINT_SPRITE); 
glPointSize(150.0f); 
shaderParticle.setUniform("projViewModelMatrix",vsml->get(VSMathLib::PROJ_VIEW_MODEL)); 
shaderParticle.setUniform("emitterPos_wor",ParticleInit); 
shaderParticle.setUniform("T",ParticleTime); 
shaderParticle.setUniform("Color",ColorParticle); 

glUseProgram(shaderParticle.getProgramIndex()); 

glBindVertexArray(m_VAO); 
glDrawElements(GL_POINTS, 0, GL_UNSIGNED_INT, 0); 
glBindVertexArray(0); 

glActiveTexture(GL_TEXTURE0); 
glBindTexture(GL_TEXTURE_2D,0); 
return true; 
} 

的問題是，什麼也沒有發生。

如果我改變這一行： glDrawElements（GL_POINTS，MAX_PARTICLES，GL_UNSIGNED_INT，0）; 碰撞系統。

我在做什麼錯？

Answer 1

頂點着色器

/* shader to update a particle system based on a simple kinematics function */ 
#version 410 core 

layout (location = 0) in vec3 v_i; // initial velocity 
layout (location = 1) in float start_time; 

uniform mat4 V, P; 
uniform vec3 emitter_pos_wor; // emitter position in world coordinates 
uniform float elapsed_system_time; // system time in seconds 

// the fragment shader can use this for it's output colour's alpha component 
out float opacity; 

void main() { 
// work out the elapsed time for _this particle_ after its start time 
float t = elapsed_system_time - start_time; 
// allow time to loop around so particle emitter keeps going 
t = mod (t, 3.0); 
opacity = 0.0; 

vec3 p = emitter_pos_wor; 
// gravity 
vec3 a = vec3 (0.0, -1.0, 0.0); 
// this is a standard kinematics equation of motion with velocity and 
// acceleration (gravity) 
p += v_i * t + 0.5 * a * t * t; 
// gradually make particle fade to invisible over 3 seconds 
opacity = 1.0 - (t/3.0); 

gl_Position = P * V * vec4 (p, 1.0); 
gl_PointSize = 15.0; // size in pixels 
} 

片段着色器

/* shader to render simple particle system points */ 
#version 410 core 

in float opacity; 
uniform sampler2D tex; // optional. enable point-sprite coords to use 
out vec4 frag_colour; 

const vec4 particle_colour = vec4 (0.4, 0.4, 0.8, 0.8); 

void main() { 
// using point texture coordinates which are pre-defined over the point 
vec4 texel = texture (tex, gl_PointCoord); 
frag_colour.a = opacity * texel.a; 
frag_colour.rgb = particle_colour.rgb * texel.rgb; 
}