From 1f4d729cfaaed2c371065bad05fe1f345d3b26ee Mon Sep 17 00:00:00 2001
From: Luke Lau <luke_lau@icloud.com>
Date: Tue, 4 Dec 2018 20:21:25 +0000
Subject: [PATCH] Add uniforms

---
 Makefile      |  3 ++-
 gles2.imports |  2 ++
 main.js       | 37 +++++++++++++++++++++++++++++++------
 test.cpp      | 16 ++++++++++++++--
 4 files changed, 49 insertions(+), 9 deletions(-)

diff --git a/Makefile b/Makefile
index c2171a2..40629ad 100644
--- a/Makefile
+++ b/Makefile
@@ -54,6 +54,7 @@ test.wasm: test.cpp sysroot
 	toolchain/build/llvm/bin/clang++ \
 		--target=wasm32-unknown-unknown-wasm -g -O3 \
 		-fno-exceptions --sysroot=sysroot -nostartfiles \
-	   	-Wl,--export=setup,--demangle,--no-entry,--allow-undefined-file=gles2.imports \
+		-I/usr/local/include \
+	   	-Wl,--export=setup,--export=update,--demangle,--no-entry,--allow-undefined-file=gles2.imports \
 		test.cpp -o test.wasm
 
diff --git a/gles2.imports b/gles2.imports
index 0982053..39ff0a1 100644
--- a/gles2.imports
+++ b/gles2.imports
@@ -11,3 +11,5 @@ glBufferData
 glGetAttribLocation
 glEnableVertexAttribArray
 glVertexAttribPointer
+glGetUniformLocation
+glUniformMatrix4fv
diff --git a/main.js b/main.js
index 3d573c1..f12efc1 100644
--- a/main.js
+++ b/main.js
@@ -33,6 +33,13 @@ function createBufferId() {
 	return id
 }
 
+const uniformLocMap = new Map()
+var currentUniformLocId = 0
+function createUniformLocId() {
+	const id = currentUniformLocId
+	currentUniformLocId += 1
+	return id
+}
 
 var memory
 var decoder = new TextDecoder('utf-8')
@@ -85,10 +92,8 @@ const imports = {
 		},
 		glLinkProgram: (progId) => gl.linkProgram(programMap.get(progId)),
 		glUseProgram: (progId) => gl.useProgram(programMap.get(progId)),
-		glGetAttribLocation: (progId, name) => {
-			const prog = programMap.get(progId)
-			return gl.getAttribLocation(prog, getString(name))
-		},
+		glGetAttribLocation: (progId, name) =>
+			gl.getAttribLocation(programMap.get(progId), getString(name)),
 		glEnableVertexAttribArray: (loc) => gl.enableVertexAttribArray(loc),
 		glVertexAttribPointer: (loc, size, type, normalized, stride, offset) => {
 			gl.vertexAttribPointer(loc, size, type, normalized, stride, offset)
@@ -105,6 +110,17 @@ const imports = {
 		glBufferData: (target, size, addr, usage) => {
 			const data = new Float32Array(memory.buffer.slice(addr, addr + size * 4))
 			gl.bufferData(target, data, usage)
+		},
+		glGetUniformLocation: (progId, name) => {
+			const id = createUniformLocId()
+			const loc = gl.getUniformLocation(programMap.get(progId), getString(name))
+			uniformLocMap.set(id, loc)
+			return id
+		},
+		glUniformMatrix4fv: (loc, count, transpose, addr) => {
+			if (count != 1) throw Error('count must be 1')
+			const vals = new Float32Array(memory.buffer.slice(addr, addr + 4 * 16))
+			gl.uniformMatrix4fv(uniformLocMap.get(loc), transpose, vals)
 		}
 	}
 }
@@ -114,6 +130,14 @@ sock.onmessage = function (e) {
 	console.log(e.data)
 }
 
+var instance
+
+function draw(tick) {
+	instance.exports.update(tick)
+	gl.drawArrays(gl.TRIANGLES, 0, 3)
+	requestAnimationFrame(draw);
+}
+
 function instantiate(bytes) {
   return WebAssembly.compile(bytes).
 		then(m => {
@@ -126,7 +150,8 @@ function instantiate(bytes) {
 fetch('test.wasm')
 	.then(response => response.arrayBuffer())
 	.then(bytes => instantiate(bytes))
-	.then(instance => {
+	.then(i => {
+		instance = i
 		instance.exports.setup()
-		gl.drawArrays(gl.TRIANGLES, 0, 3)
+		requestAnimationFrame(draw);
 	})
diff --git a/test.cpp b/test.cpp
index 065ed80..cbdf370 100644
--- a/test.cpp
+++ b/test.cpp
@@ -1,11 +1,15 @@
 #include <GLES3/gl32.h>
 #include <string>
 #include <vector>
+#include <glm/glm.hpp>
+#include <glm/ext.hpp>
+#include <glm/gtc/type_ptr.hpp>
 
 const char* vertShaderSrc = R"(
 attribute vec4 vertPos;
+uniform mat4 model;
 void main() {
-	gl_Position = vertPos;
+	gl_Position = model * vertPos;
 }
 )";
 
@@ -15,6 +19,8 @@ void main() {
 }
 )";
 
+GLuint program;
+
 extern "C" void setup() {
 	GLuint vertShader = glCreateShader(GL_VERTEX_SHADER);
 	const char* sources[1] = { vertShaderSrc };
@@ -28,7 +34,7 @@ extern "C" void setup() {
 			new const GLint[1] { (GLint)strlen(fragShaderSrc) });
 	glCompileShader(fragShader);
 
-	GLuint program = glCreateProgram();
+	program = glCreateProgram();
 	glAttachShader(program, vertShader);
 	glAttachShader(program, fragShader);
 	glLinkProgram(program);
@@ -48,3 +54,9 @@ extern "C" void setup() {
 	glEnableVertexAttribArray(vertPosLoc);
 	glVertexAttribPointer(vertPosLoc, 3, GL_FLOAT, false, 0, 0);
 }
+
+extern "C" void update(int tick) {
+	GLuint modelLoc = glGetUniformLocation(program, "model");
+	const glm::mat4 model = glm::rotate(glm::mat4(1), (float)tick * 0.001f, glm::vec3(0, 0, 1));
+	glUniformMatrix4fv(modelLoc, 1, false, glm::value_ptr(model));
+}
-- 
2.30.2