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ShaderLesson3 Ported to LibGDX
import com.badlogic.gdx.ApplicationListener;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.backends.lwjgl.LwjglApplication;
import com.badlogic.gdx.backends.lwjgl.LwjglApplicationConfiguration;
import com.badlogic.gdx.graphics.GL10;
import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.graphics.glutils.ShaderProgram;
/**
* A port of ShaderLesson3 from lwjgl-basics to LibGDX:
* https://github.com/mattdesl/lwjgl-basics/wiki/ShaderLesson3
*
* @author davedes
*/
public class ShaderLesson3 implements ApplicationListener {
//Minor differences:
//LibGDX Position attribute is a vec4
//u_projView is called u_projTrans
//we need to set ShaderProgram.pedantic to false
//LibGDX uses lower-left as origin (0, 0)
//TexCoord attribute requires "0" appended at end to denote GL_TEXTURE0
//ShaderProgram.TEXCOORD_ATTRIBUTE+"0"
//It's wise to use LOWP when possible in GL ES, for values between 0-1
//In LibGDX ShaderProgram uses begin() and end()
public static void main(String[] args) {
LwjglApplicationConfiguration cfg = new LwjglApplicationConfiguration();
cfg.title = "Shader Lesson 3 - LibGDX";
cfg.useGL20 = true;
cfg.width = 320;
cfg.height = 240;
cfg.resizable = false;
new LwjglApplication(new ShaderLesson3(), cfg);
}
final String VERT =
"attribute vec4 "+ShaderProgram.POSITION_ATTRIBUTE+";\n" +
"attribute vec4 "+ShaderProgram.COLOR_ATTRIBUTE+";\n" +
"attribute vec2 "+ShaderProgram.TEXCOORD_ATTRIBUTE+"0;\n" +
"uniform mat4 u_projTrans;\n" +
" \n" +
"varying vec4 vColor;\n" +
"varying vec2 vTexCoord;\n" +
"void main() {\n" +
" vColor = "+ShaderProgram.COLOR_ATTRIBUTE+";\n" +
" vTexCoord = "+ShaderProgram.TEXCOORD_ATTRIBUTE+"0;\n" +
" gl_Position = u_projTrans * " + ShaderProgram.POSITION_ATTRIBUTE + ";\n" +
"}";
//This will be dumped to System.out for clarity
final String FRAG =
//GL ES specific stuff
"#ifdef GL_ES\n" //
+ "#define LOWP lowp\n" //
+ "precision mediump float;\n" //
+ "#else\n" //
+ "#define LOWP \n" //
+ "#endif\n" + //
"//texture 0\n" +
"uniform sampler2D u_texture;\n" +
"\n" +
"//our screen resolution, set from Java whenever the display is resized\n" +
"uniform vec2 resolution;\n" +
"\n" +
"//\"in\" attributes from our vertex shader\n" +
"varying LOWP vec4 vColor;\n" +
"varying vec2 vTexCoord;\n" +
"\n" +
"//RADIUS of our vignette, where 0.5 results in a circle fitting the screen\n" +
"const float RADIUS = 0.75;\n" +
"\n" +
"//softness of our vignette, between 0.0 and 1.0\n" +
"const float SOFTNESS = 0.45;\n" +
"\n" +
"//sepia colour, adjust to taste\n" +
"const vec3 SEPIA = vec3(1.2, 1.0, 0.8); \n" +
"\n" +
"void main() {\n" +
" //sample our texture\n" +
" vec4 texColor = texture2D(u_texture, vTexCoord);\n" +
" \n" +
" //1. VIGNETTE\n" +
" \n" +
" //determine center position\n" +
" vec2 position = (gl_FragCoord.xy / resolution.xy) - vec2(0.5);\n" +
" \n" +
" //determine the vector length of the center position\n" +
" float len = length(position);\n" +
" \n" +
" //use smoothstep to create a smooth vignette\n" +
" float vignette = smoothstep(RADIUS, RADIUS-SOFTNESS, len);\n" +
" \n" +
" //apply the vignette with 50% opacity\n" +
" texColor.rgb = mix(texColor.rgb, texColor.rgb * vignette, 0.5);\n" +
" \n" +
" //2. GRAYSCALE\n" +
" \n" +
" //convert to grayscale using NTSC conversion weights\n" +
" float gray = dot(texColor.rgb, vec3(0.299, 0.587, 0.114));\n" +
" \n" +
" //3. SEPIA\n" +
" \n" +
" //create our sepia tone from some constant value\n" +
" vec3 sepiaColor = vec3(gray) * SEPIA;\n" +
" \n" +
" //again we'll use mix so that the sepia effect is at 75%\n" +
" texColor.rgb = mix(texColor.rgb, sepiaColor, 0.75);\n" +
" \n" +
" //final colour, multiplied by vertex colour\n" +
" gl_FragColor = texColor * vColor;\n" +
"}";
Texture tex;
SpriteBatch batch;
OrthographicCamera cam;
ShaderProgram shader;
@Override
public void create() {
//the texture does not matter since we will ignore it anyways
tex = new Texture(Gdx.files.internal("data/scene.png"));
//important since we aren't using some uniforms and attributes that SpriteBatch expects
ShaderProgram.pedantic = false;
//print it out for clarity
System.out.println("Vertex Shader:\n-------------\n\n"+VERT);
System.out.println("\n");
System.out.println("Fragment Shader:\n-------------\n\n"+FRAG);
shader = new ShaderProgram(VERT, FRAG);
if (!shader.isCompiled()) {
System.err.println(shader.getLog());
System.exit(0);
}
if (shader.getLog().length()!=0)
System.out.println(shader.getLog());
batch = new SpriteBatch(1000, shader);
batch.setShader(shader);
cam = new OrthographicCamera(Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
cam.setToOrtho(false);
}
@Override
public void resize(int width, int height) {
cam.setToOrtho(false, width, height);
batch.setProjectionMatrix(cam.combined);
//bind the shader, then set the uniform, then unbind the shader
shader.begin();
shader.setUniformf("resolution", width, height);
shader.end();
}
@Override
public void render() {
Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
batch.begin();
batch.draw(tex, 0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
batch.end();
}
@Override
public void pause() {
}
@Override
public void resume() {
}
@Override
public void dispose() {
batch.dispose();
shader.dispose();
tex.dispose();
}
}
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