Need example code for texture shader

a1z3n

Hi. I trying to draw texture on shader, but its not work. What I do wrong? bg drawn correct.

PShader mShader;
    PImage bg;
    PImage tex;
    void setup() {
      size(640, 360, P2D);
      noStroke();
      textureMode(NORMAL);
      bg = loadImage("bg.jpg");
      tex = loadImage("smoke.png");
      mShader = loadShader("texfrag.glsl", "texvert.glsl");
      mShader.set("texture", tex);
      background(255);
    }
    void draw() {
      image(bg,0,0);
      shader(mShader);
    }

texfrag.glsl:

#ifdef GL_ES
precision mediump float;
precision mediump int;
#endif

uniform sampler2D texture;

varying vec4 vertColor;
varying vec4 vertTexCoord;

void main() {
  gl_FragColor = texture2D(texture, vertTexCoord.st) * vertColor;
}

texvert.glsl:

uniform mat4 transform;
uniform mat4 texMatrix;

attribute vec4 position;
attribute vec4 color;
attribute vec2 texCoord;

varying vec4 vertColor;
varying vec4 vertTexCoord;
uniform sampler2D texture;

void main() {
  gl_Position = transform * position;
  vertColor = color;
  vertTexCoord = texMatrix * vec4(texCoord, 1.0, 1.0);
}

Or need sample code for texture draw on shader.

koogs

what exactly are you drawing? there's nothing after the shader in draw. try drawing a rectangle.

look at the example in the reference. it sets the shader and then draws an image. every pixel in the image is affected by the shader.

a1z3n

I want to draw the image and morph it. I read all reference but not found how to draw simple 2D texture on shader.

jeremydouglass

Correct way:

1. set shader setting
2. draw (shaded) thing

Like in the reference example:

void draw() {
  shader(edges);
  image(img, 0, 0);
}

What you are doing:

void draw() {
  image(bg,0,0);    // draw unshaded image
  shader(mShader);  // set shader, then don't draw anything
}

...that is wrong.

kfrajer

Check this in https://processing.org/tutorials/pshader/

Section: texture shaders, code listing 5.1

Also you should check https://processing.org/reference/texture_.html as it might do what you want in case you are feeding your texture externally.

Kf

a1z3n

Thanks, I set image(tex,0,0); after shader(mShader); and it works, but bg also morphed :|

koogs

Actual code is more useful than short descriptions of your problem.