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我寫了一個小程序來簡單解釋我的問題，我嘗試改變圖像的像素位置，其中紋理元素x是方向，另一個表示速度。最終目標是使用我的CPU數據，在那裏計算NAVIER-STROKE流體來移動GLSL中的像素。 CPU代碼在Processing java庫中。 我試着去看看我的代碼中有什麼bug，但我不明白像素轉換是如何工作的。 在第一個我轉換我的方向在顏色值從0到255在CPU中，並在GPU轉換這一個向量方向，並乘以這個速度和規模這一個在1x1，但這是行不通的。 ..對不起，如果我的解釋不是很可靠，但英文不是很流利。移動具有紋理方向和紋理速度的像素/ GLSL
處理：
PImage tex_velocity, tex_direction ;
PShader warping;
PImage img ;
int grid_w, grid_h ;
void setup() {
size(600,375,P2D);
// img = loadImage("pirate_small.jpg");
img = loadImage("puros_girl_small.jpg");
grid_w = 60 ;
grid_h = 37 ;
tex_velocity = createImage(grid_w,grid_h,RGB);
tex_direction = createImage(grid_w,grid_h,RGB);
warping = loadShader("shader/warp/rope_warp_frag.glsl");
noise_img(tex_velocity, 20, .1, .1); // max translate for the pixel
noise_img(tex_direction, 360, .1, .1); // degree direction
}
void draw() {
println(frameRate);
if(frameCount%30 == 0) {
noise_img(tex_velocity, 20, .1, .1); // max translate for the pixel
noise_img(tex_direction, 360, .1, .1); // degree direction
}
warping.set("mode", 0) ;
warping.set("texture",img);
warping.set("roof_component_colour",g.colorModeX);
warping.set("wh_ratio",1f/grid_w, 1f/grid_h);
warping.set("vel_texture",tex_velocity);
warping.set("dir_texture",tex_direction);
shader(warping);
image(img,0,0);
resetShader();
image(tex_velocity,5,5);
image(tex_direction,grid_w +15 ,5);
}
float x_offset, y_offset ;
void noise_img(PImage dst, int max, float ratio_x, float ratio_y) {
noiseSeed((int)random(10000));
for(int x = 0 ; x < dst.width ; x++) {
x_offset += ratio_x ;
for(int y = 0 ; y < dst.height ; y++) {
y_offset += ratio_y ;
float v = map(noise(x_offset,y_offset),0,1,0,max);
v = (int)map(v,0,max,0,g.colorModeX);
int c = color(v,v,v,g.colorModeA) ;
dst.set(x,y,c);
}
}
}
GLSL
#ifdef GL_ES
precision mediump float;
precision mediump int;
#endif
#define PROCESSING_TEXTURE_SHADER
#define PI 3.1415926535897932384626433832795
varying vec4 vertTexCoord;
uniform sampler2D texture;
uniform int mode;
uniform float roof_component_colour;
uniform sampler2D vel_texture;
uniform sampler2D dir_texture;
uniform vec2 wh_ratio;
float map(float value, float start1, float stop1, float start2, float stop2) {
float result = start2 + (stop2 - start2) * ((value - start1)/(stop1 - start1));
return result;
}
vec2 cartesian_coord(float angle) {
float x = cos(angle);
float y = sin(angle);
return vec2(x,y);
}
vec2 translate(float fdir, float fvel) {
float angle_in_radian = map(fdir, 0, roof_component_colour, -PI, PI);
vec2 dir_cart = cartesian_coord(angle_in_radian);
return dir_cart *fvel ;
}
void main() {
vec2 ratio = gl_FragCoord.xy *wh_ratio;
vec4 vel = texture2D(vel_texture, ratio);
vec4 dir = texture2D(dir_texture, ratio);
// rendering picture ;
if(mode == 0) {
float direction = dir.x;
float velocity = vel.x;
vec2 translation = translate(direction,velocity);
// not bad, but totaly wrong
// vec2 coord_dest = vertTexCoord.st +translation
vec2 coord_dest = vertTexCoord.st *ratio +translation ;
// not bad, but totaly wrong
vec2 coord_dest = vertTexCoord.st *ratio +translation ;
vec4 tex_colour = texture2D(texture, coord_dest);
gl_FragColor = tex_colour;
}
// velocity
if(mode == 1) {
gl_FragColor = texture2D(vel_texture, vertTexCoord.st);;
}
// direction force field
if(mode == 2) {
gl_FragColor = texture2D(dir_texture, vertTexCoord.st);;
}
}
