126 lines
6.8 KiB
Java
126 lines
6.8 KiB
Java
// taken from Texample,
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// http://fractiousg.blogspot.com/201/4/rendering-text-in-opengl-on-android.html
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package com.android.texample;
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// import android.util.FloatMath;
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import javax.microedition.khronos.opengles.GL10;
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public class SpriteBatch {
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//--Constants--//
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final static int VERTEX_SIZE = 4; // Vertex Size (in Components) ie. (X,Y,U,V)
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final static int VERTICES_PER_SPRITE = 4; // Vertices Per Sprite
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final static int INDICES_PER_SPRITE = 6; // Indices Per Sprite
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//--Members--//
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GL10 gl; // GL Instance
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Vertices vertices; // Vertices Instance Used for Rendering
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float[] vertexBuffer; // Vertex Buffer
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int bufferIndex; // Vertex Buffer Start Index
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int maxSprites; // Maximum Sprites Allowed in Buffer
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int numSprites; // Number of Sprites Currently in Buffer
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//--Constructor--//
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// D: prepare the sprite batcher for specified maximum number of sprites
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// A: gl - the gl instance to use for rendering
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// maxSprites - the maximum allowed sprites per batch
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public SpriteBatch(GL10 gl, int maxSprites) {
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this.gl = gl; // Save GL Instance
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this.vertexBuffer = new float[maxSprites * VERTICES_PER_SPRITE * VERTEX_SIZE]; // Create Vertex Buffer
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this.vertices = new Vertices( gl, maxSprites * VERTICES_PER_SPRITE, maxSprites * INDICES_PER_SPRITE, false, true, false ); // Create Rendering Vertices
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this.bufferIndex = 0; // Reset Buffer Index
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this.maxSprites = maxSprites; // Save Maximum Sprites
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this.numSprites = 0; // Clear Sprite Counter
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short[] indices = new short[maxSprites * INDICES_PER_SPRITE]; // Create Temp Index Buffer
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int len = indices.length; // Get Index Buffer Length
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short j = 0; // Counter
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for ( int i = 0; i < len; i+= INDICES_PER_SPRITE, j += VERTICES_PER_SPRITE ) { // FOR Each Index Set (Per Sprite)
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indices[i + 0] = (short)( j + 0 ); // Calculate Index 0
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indices[i + 1] = (short)( j + 1 ); // Calculate Index 1
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indices[i + 2] = (short)( j + 2 ); // Calculate Index 2
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indices[i + 3] = (short)( j + 2 ); // Calculate Index 3
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indices[i + 4] = (short)( j + 3 ); // Calculate Index 4
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indices[i + 5] = (short)( j + 0 ); // Calculate Index 5
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}
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vertices.setIndices( indices, 0, len ); // Set Index Buffer for Rendering
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}
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//--Begin Batch--//
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// D: signal the start of a batch. set the texture and clear buffer
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// NOTE: the overloaded (non-texture) version assumes that the texture is already bound!
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// A: textureId - the ID of the texture to use for the batch
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// R: [none]
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public void beginBatch(int textureId) {
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gl.glBindTexture( GL10.GL_TEXTURE_2D, textureId ); // Bind the Texture
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numSprites = 0; // Empty Sprite Counter
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bufferIndex = 0; // Reset Buffer Index (Empty)
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}
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public void beginBatch() {
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numSprites = 0; // Empty Sprite Counter
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bufferIndex = 0; // Reset Buffer Index (Empty)
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}
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//--End Batch--//
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// D: signal the end of a batch. render the batched sprites
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// A: [none]
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// R: [none]
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public void endBatch() {
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if ( numSprites > 0 ) { // IF Any Sprites to Render
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vertices.setVertices( vertexBuffer, 0, bufferIndex ); // Set Vertices from Buffer
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vertices.bind(); // Bind Vertices
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vertices.draw( GL10.GL_TRIANGLES, 0, numSprites * INDICES_PER_SPRITE ); // Render Batched Sprites
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vertices.unbind(); // Unbind Vertices
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}
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}
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//--Draw Sprite to Batch--//
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// D: batch specified sprite to batch. adds vertices for sprite to vertex buffer
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// NOTE: MUST be called after beginBatch(), and before endBatch()!
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// NOTE: if the batch overflows, this will render the current batch, restart it,
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// and then batch this sprite.
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// A: x, y - the x,y position of the sprite (center)
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// width, height - the width and height of the sprite
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// region - the texture region to use for sprite
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// R: [none]
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public void drawSprite(float x, float y, float width, float height, TextureRegion region) {
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if ( numSprites == maxSprites ) { // IF Sprite Buffer is Full
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endBatch(); // End Batch
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// NOTE: leave current texture bound!!
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numSprites = 0; // Empty Sprite Counter
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bufferIndex = 0; // Reset Buffer Index (Empty)
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}
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float halfWidth = width / 2.0f; // Calculate Half Width
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float halfHeight = height / 2.0f; // Calculate Half Height
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float x1 = x - halfWidth; // Calculate Left X
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float y1 = y - halfHeight; // Calculate Bottom Y
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float x2 = x + halfWidth; // Calculate Right X
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float y2 = y + halfHeight; // Calculate Top Y
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vertexBuffer[bufferIndex++] = x1; // Add X for Vertex 0
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vertexBuffer[bufferIndex++] = y1; // Add Y for Vertex 0
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vertexBuffer[bufferIndex++] = region.u1; // Add U for Vertex 0
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vertexBuffer[bufferIndex++] = region.v2; // Add V for Vertex 0
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vertexBuffer[bufferIndex++] = x2; // Add X for Vertex 1
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vertexBuffer[bufferIndex++] = y1; // Add Y for Vertex 1
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vertexBuffer[bufferIndex++] = region.u2; // Add U for Vertex 1
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vertexBuffer[bufferIndex++] = region.v2; // Add V for Vertex 1
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vertexBuffer[bufferIndex++] = x2; // Add X for Vertex 2
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vertexBuffer[bufferIndex++] = y2; // Add Y for Vertex 2
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vertexBuffer[bufferIndex++] = region.u2; // Add U for Vertex 2
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vertexBuffer[bufferIndex++] = region.v1; // Add V for Vertex 2
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vertexBuffer[bufferIndex++] = x1; // Add X for Vertex 3
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vertexBuffer[bufferIndex++] = y2; // Add Y for Vertex 3
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vertexBuffer[bufferIndex++] = region.u1; // Add U for Vertex 3
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vertexBuffer[bufferIndex++] = region.v1; // Add V for Vertex 3
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numSprites++; // Increment Sprite Count
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}
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}
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