abstraction layer for attribute index/stride/offset

1 files changed, 49 insertions, 0 deletions

diff --git a/src/main/java/makamys/neodymium/renderer/attribs/AttributeSet.java b/src/main/java/makamys/neodymium/renderer/attribs/AttributeSet.java
new file mode 100644
index 0000000..ebf9c4c
--- /dev/null
+++ b/src/main/java/makamys/neodymium/renderer/attribs/AttributeSet.java
@@ -0,0 +1,49 @@
+package makamys.neodymium.renderer.attribs;
+
+import org.lwjgl.opengl.GL20;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+public class AttributeSet {
+    private final List<VertexAttribute> attributes = new ArrayList<>();
+
+    public void addAttribute(String name, int size, int elementSize, int type) {
+        int index = attributes.size();
+        attributes.add(new VertexAttribute(name, index, size, elementSize, type));
+    }
+
+    public void enable() {
+        int stride = attributes.stream().mapToInt(attrib -> attrib.size * attrib.elementSize).sum();
+        int offset = 0;
+        for (int i = 0, size = attributes.size(); i < size; i++) {
+            VertexAttribute attribute = attributes.get(i);
+            GL20.glVertexAttribPointer(i, attribute.size, attribute.type, false, stride, offset);
+            offset += attribute.size * attribute.elementSize;
+            GL20.glEnableVertexAttribArray(i);
+        }
+    }
+
+    public void addDefines(Map<String, String> defines) {
+        for (VertexAttribute attribute: attributes) {
+            defines.put("ATTRIB_" + attribute.name, Integer.toString(attribute.index));
+        }
+    }
+
+    public static class VertexAttribute {
+        public final String name;
+        public final int index;
+        public final int size;
+        public final int elementSize;
+        public final int type;
+
+        private VertexAttribute(String name, int index, int size, int elementSize, int type) {
+            this.name = name;
+            this.index = index;
+            this.size = size;
+            this.elementSize = elementSize;
+            this.type = type;
+        }
+    }
+}