Renderer.java

package com.atm959.openglgame;

import android.opengl.GLES20;
import android.opengl.Matrix;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;

public class Renderer {

    private String vertexShaderCode =
                    "attribute vec2 aPos;" +
                    "attribute vec2 aTexCoord;" +
                    "uniform mat4 projection;" +
                    "uniform mat4 model;" +
                    "varying vec2 vTexCoord;" +
                    "void main(){" +
                    "    gl_Position = projection * model * vec4(aPos, 0.0, 1.0);" +
                    "    vTexCoord = aTexCoord;" +
                    "}";

    private String fragmentShaderCode =
                    "precision mediump float;" +
                    "varying vec2 vTexCoord;" +
                    "uniform sampler2D tex;" +
                    "void main(){" +
                    "    gl_FragColor = texture2D(tex, vTexCoord);" +
                    "}";

    static final float[] vertexCoords = {   // in counterclockwise order:
            0.0f, 0.0f,
            0.0f, 1.0f,
            1.0f, 1.0f,
            0.0f, 0.0f,
            1.0f, 1.0f,
            1.0f, 0.0f,
    };

    static final float[] textureCoords = {
            0.0f, 0.0f,
            0.0f, 1.0f,
            1.0f, 1.0f,
            0.0f, 0.0f,
            1.0f, 1.0f,
            1.0f, 0.0f
    };

    static final int COORDS_PER_VERTEX = 2;
    private final int vertexCount = vertexCoords.length / COORDS_PER_VERTEX;
    private final int vertexStride = COORDS_PER_VERTEX * 4;

    private FloatBuffer vertexBuffer;
    private FloatBuffer textureCoordsBuffer;
    private int mProgram;

    private int mPositionHandle;
    private int mTexCoordHandle;
    private int mProjectionMatrixHandle;
    private int mModelMatrixHandle;
    private int mTexHandle;

    float[] projection = new float[16];
    float[] model = new float[16];

    int screenWidth;
    int screenHeight;

    public Renderer(int screenWidth, int screenHeight){
        this.screenWidth = screenWidth;
        this.screenHeight = screenHeight;
        Matrix.setIdentityM(this.projection, 0);
        Matrix.setIdentityM(this.model, 0);

        ByteBuffer bb = ByteBuffer.allocateDirect(vertexCoords.length * 4);
        bb.order(ByteOrder.nativeOrder());
        this.vertexBuffer = bb.asFloatBuffer();
        this.vertexBuffer.put(vertexCoords);
        this.vertexBuffer.position(0);

        bb = ByteBuffer.allocateDirect(textureCoords.length * 4);
        bb.order(ByteOrder.nativeOrder());
        this.textureCoordsBuffer = bb.asFloatBuffer();
        this.textureCoordsBuffer.put(textureCoords);
        this.textureCoordsBuffer.position(0);

        int vertexShader = MyGLRenderer.loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode);
        int fragmentShader = MyGLRenderer.loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode);
        this.mProgram = GLES20.glCreateProgram();
        GLES20.glAttachShader(this.mProgram, vertexShader);
        GLES20.glAttachShader(this.mProgram, fragmentShader);
        GLES20.glLinkProgram(this.mProgram);

        this.mPositionHandle = GLES20.glGetAttribLocation(this.mProgram, "aPos");
        this.mTexCoordHandle = GLES20.glGetAttribLocation(this.mProgram, "aTexCoord");
        this.mProjectionMatrixHandle = GLES20.glGetUniformLocation(this.mProgram, "projection");
        this.mModelMatrixHandle = GLES20.glGetUniformLocation(this.mProgram, "model");
        this.mTexHandle = GLES20.glGetUniformLocation(this.mProgram, "tex");
    }

    public void setScreenSize(int width, int height){
        this.screenWidth = width;
        this.screenHeight = height;
    }

    public void update(){
        Matrix.setIdentityM(this.projection, 0);
        Matrix.orthoM(this.projection, 0, 0.0f, this.screenWidth, this.screenHeight, 0.0f, -1.0f, 1.0f);
    }

    public void renderImageBasic(int x, int y, int width, int height, int texUnit){
        ByteBuffer bb = ByteBuffer.allocateDirect(textureCoords.length * 4);
        bb.order(ByteOrder.nativeOrder());
        this.textureCoordsBuffer = bb.asFloatBuffer();
        this.textureCoordsBuffer.put(textureCoords);
        this.textureCoordsBuffer.position(0);

        Matrix.setIdentityM(this.model, 0);
        Matrix.translateM(this.model, 0, x, y, 0.0f);
        Matrix.scaleM(this.model, 0, width, height, 1.0f);

        GLES20.glUseProgram(this.mProgram);

        GLES20.glEnableVertexAttribArray(this.mPositionHandle);
        GLES20.glEnableVertexAttribArray(this.mTexCoordHandle);

        GLES20.glVertexAttribPointer(this.mPositionHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, this.vertexBuffer);
        GLES20.glVertexAttribPointer(this.mTexCoordHandle, 2, GLES20.GL_FLOAT, false, 2*4, this.textureCoordsBuffer);

        GLES20.glUniformMatrix4fv(this.mProjectionMatrixHandle, 1, false, this.projection, 0);
        GLES20.glUniformMatrix4fv(this.mModelMatrixHandle, 1, false, this.model, 0);

        GLES20.glUniform1i(this.mTexHandle, texUnit);

        GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, vertexCount);

        GLES20.glDisableVertexAttribArray(this.mPositionHandle);
        GLES20.glDisableVertexAttribArray(this.mTexCoordHandle);
    }

    public void renderImageTexCoords(int x, int y, int width, int height, float u1, float v1, float u2, float v2, int texUnit){
        float[] texCoords = {
                u1, v1,
                u1, v2,
                u2, v2,
                u1, v1,
                u2, v2,
                u2, v1
        };

        ByteBuffer bb = ByteBuffer.allocateDirect(texCoords.length * 4);
        bb.order(ByteOrder.nativeOrder());
        this.textureCoordsBuffer = bb.asFloatBuffer();
        this.textureCoordsBuffer.put(texCoords);
        this.textureCoordsBuffer.position(0);

        Matrix.setIdentityM(this.model, 0);
        Matrix.translateM(this.model, 0, x, y, 0.0f);
        Matrix.scaleM(this.model, 0, width, height, 1.0f);

        GLES20.glUseProgram(this.mProgram);

        GLES20.glEnableVertexAttribArray(this.mPositionHandle);
        GLES20.glEnableVertexAttribArray(this.mTexCoordHandle);

        GLES20.glVertexAttribPointer(this.mPositionHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, this.vertexBuffer);
        GLES20.glVertexAttribPointer(this.mTexCoordHandle, 2, GLES20.GL_FLOAT, false, 2*4, this.textureCoordsBuffer);

        GLES20.glUniformMatrix4fv(this.mProjectionMatrixHandle, 1, false, this.projection, 0);
        GLES20.glUniformMatrix4fv(this.mModelMatrixHandle, 1, false, this.model, 0);

        GLES20.glUniform1i(this.mTexHandle, texUnit);

        GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, vertexCount);

        GLES20.glDisableVertexAttribArray(this.mPositionHandle);
        GLES20.glDisableVertexAttribArray(this.mTexCoordHandle);
    }
}