From 249833947ff691dd79453c4d817387a6922236d6 Mon Sep 17 00:00:00 2001
From: sanine <sanine.not@pm.me>
Date: Mon, 22 Aug 2022 11:38:26 -0500
Subject: add element buffers

---
 demo/honey.lua   | 20 ++++++++++++----
 src/gl/data.c    | 72 +++++++++++++++++++++++++++++---------------------------
 src/gl/drawing.c | 11 +++++++++
 src/gl/gl.c      |  3 ++-
 4 files changed, 65 insertions(+), 41 deletions(-)

diff --git a/demo/honey.lua b/demo/honey.lua
index 5e14461..2b1759f 100644
--- a/demo/honey.lua
+++ b/demo/honey.lua
@@ -62,14 +62,20 @@ gl.shader.delete(fragmentShader)
 
 
 local vertices = {
-    -0.5, -0.5, 0.0,
-     0.5, -0.5, 0.0,
-     0.0,  0.5, 0.0
-}  
+	 0.5,  0.5, 0.0,
+	 0.5, -0.5, 0.0,
+	-0.5, -0.5, 0.0,
+	-0.5,  0.5, 0.0
+}
+local indices = {
+        0, 1, 3,
+        1, 2, 3
+}
 
 local vertexArray = gl.data.createVertexArray()
 
 local vertexBuffer = gl.data.createBuffer()
+local elementBuffer = gl.data.createBuffer()
 gl.data.bindVertexArray(vertexArray)
 
 gl.data.bindBuffer(gl.data.bufferTarget.arrayBuffer, vertexBuffer)
@@ -78,6 +84,9 @@ if err ~= gl.errorType.noError then error(gl.errorName(err)) end
 gl.data.bufferData(gl.data.bufferTarget.arrayBuffer, gl.dataType.float, vertices, gl.data.bufferUsage.staticDraw)
 if gl.getError() ~= gl.errorType.noError then error(gl.getError()) end
 
+gl.data.bindBuffer(gl.data.bufferTarget.elementArrayBuffer, elementBuffer)
+gl.data.bufferData(gl.data.bufferTarget.elementArrayBuffer, gl.dataType.uint, indices, gl.data.bufferUsage.staticDraw)
+
 gl.data.vertexAttribPointer(0, 3, false, 3, 0)
 if gl.getError() ~= gl.errorType.noError then error(gl.getError()) end
 gl.data.vertexArrayEnableAttrib(0)
@@ -92,7 +101,8 @@ while not window.shouldClose(w) do
 
 	gl.shader.use(shader)
 	gl.data.bindVertexArray(vertexArray)
-	gl.draw.drawArrays(gl.draw.primitiveType.triangles, 0, 3)
+	--gl.draw.drawArrays(gl.draw.primitiveType.triangles, 0, 3)
+	gl.draw.drawElements(gl.draw.primitiveType.triangles, 6, gl.dataType.uint, 0)
 
 	window.swapBuffers(w)
 	window.pollEvents()
diff --git a/src/gl/data.c b/src/gl/data.c
index f598784..777689a 100644
--- a/src/gl/data.c
+++ b/src/gl/data.c
@@ -65,48 +65,50 @@ int gl_bind_buffer(lua_State *L)
 }
 
 
+#define GET_BUFFER_TYPE(type, name, conversion) \
+	void * get_buffer_ ## name (lua_State *L, size_t *sz, int tbl) { \
+		size_t len = lua_objlen(L, tbl); \
+		*sz = len * sizeof(type); \
+		type *buf = malloc(*sz); \
+		if (buf == NULL) \
+			hs_throw_error(L, "failed to allocate intermediary buffer"); \
+		for (int i=0; i<len; i++) { \
+			lua_rawgeti(L, tbl, i+1); \
+			if (!lua_isnumber(L, -1)) \
+				hs_throw_error(L, "all elements must be numbers (failed at index %d)", i); \
+			buf[i] = conversion(L, -1); \
+			lua_pop(L, 1); \
+		} \
+		return buf; \
+	}
+
+GET_BUFFER_TYPE(unsigned int, uint, lua_tointeger)
+GET_BUFFER_TYPE(int, int, lua_tointeger)
+GET_BUFFER_TYPE(float, float, lua_tonumber)
+
 int gl_buffer_data(lua_State *L)
 {
 	lua_Integer target, type, usage;
 	int table;
 	hs_parse_args(L, hs_int(target), hs_int(type), hs_tbl(table), hs_int(usage));
 
-	if (type != GL_INT && type != GL_FLOAT) {
-		hs_throw_error(L, "invalid type");
-	}
-
 	/* build raw buffer */
-	size_t len = lua_objlen(L, table);
-	void *buf;
-	if (type == GL_FLOAT) {
-		float *fbuf = malloc(len * sizeof(float));
-		if (fbuf == NULL)
-			hs_throw_error(L, "failed to allocate intermediary fbuffer");
-		for (int i=0; i<len; i++) {
-			lua_rawgeti(L, table, i+1);
-			if (!lua_isnumber(L, -1)) {
-				hs_throw_error(L, "all table items must be numbers (failed at index %d)", i);
-			}
-			fbuf[i] = lua_tonumber(L, -1);
-			lua_pop(L, 1);
-		}
-		len = len * sizeof(float);
-		buf = fbuf;
-	}
-	else {
-		int *ibuf = malloc(len * sizeof(int));
-		if (ibuf == NULL)
-			hs_throw_error(L, "failed to allocate intermediary ibuffer");
-		for (int i=0; i<len; i++) {
-			lua_rawgeti(L, table, i+1);
-			if (!lua_isnumber(L, -1)) {
-				hs_throw_error(L, "all table items must be integers (failed at index %d)", i);
-			}
-			ibuf[i] = lua_tointeger(L, -1);
-			lua_pop(L, 1);
-		}
-		len = len * sizeof(int);
-		buf = ibuf;
+	void *buf; size_t len;
+	switch(type) {
+	case GL_UNSIGNED_INT:
+		buf = get_buffer_uint(L, &len, table);
+		break;
+
+	case GL_INT:
+		buf = get_buffer_int(L, &len, table);
+		break;
+
+	case GL_FLOAT:
+		buf = get_buffer_float(L, &len, table);
+		break;
+
+	default:
+		hs_throw_error(L, "invalid type");
 	}
 
 	/* call */
diff --git a/src/gl/drawing.c b/src/gl/drawing.c
index a64f56d..ca914e0 100644
--- a/src/gl/drawing.c
+++ b/src/gl/drawing.c
@@ -5,6 +5,7 @@
 
 int gl_set_viewport(lua_State *L);
 int gl_draw_arrays(lua_State *L);
+int gl_draw_elements(lua_State *L);
 int gl_set_clear_color(lua_State *L);
 int gl_clear(lua_State *L);
 
@@ -24,6 +25,7 @@ void setup_drawing(lua_State *L, int gl_index)
 
 	hs_create_table(L,
 		hs_str_cfunc("drawArrays", gl_draw_arrays),
+		hs_str_cfunc("drawElements", gl_draw_elements),
 		hs_str_cfunc("setClearColor", gl_set_clear_color),
 		hs_str_cfunc("clear", gl_clear),
 		hs_str_cfunc("setViewport", gl_set_viewport),
@@ -62,6 +64,15 @@ int gl_draw_arrays(lua_State *L)
 }
 
 
+int gl_draw_elements(lua_State *L)
+{
+	lua_Integer mode, count, type, offset;
+	hs_parse_args(L, hs_int(mode), hs_int(count), hs_int(type), hs_int(offset));
+	glDrawElements(mode, count, type, (const void*)offset);
+	return 0;
+}
+
+
 int gl_set_viewport(lua_State *L)
 {
 	lua_Integer x, y, w, h;
diff --git a/src/gl/gl.c b/src/gl/gl.c
index 8a1cb17..8f56d33 100644
--- a/src/gl/gl.c
+++ b/src/gl/gl.c
@@ -21,7 +21,8 @@ int gl_get_error(lua_State *L);
 void setup_gl(lua_State *L, int honey_index)
 {
 	int data_types = hs_create_table(L,
-		hs_str_int("integer", GL_INT),
+		hs_str_int("uint", GL_UNSIGNED_INT),
+		hs_str_int("int", GL_INT),
 		hs_str_int("float", GL_FLOAT),
 	);
 
-- 
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