From 838c1c0c6fed73333254d7caa204e2fe9f3c1620 Mon Sep 17 00:00:00 2001
From: Cassie Jones <code@witchoflight.com>
Date: Thu, 30 Jan 2020 16:28:55 -0500
Subject: [PATCH] =?utf8?q?Initial=20commit,=20stymied=20by=20L=C3=96VR=20b?=
 =?utf8?q?ugs?=
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This adds a main test program and a simple (currently broken) sprite
billboarding shader. It doesn't have much going on, because I'm running
into a LÖVR bug with sending compute ShaderBlock data on Oculus Quest.
---
 .vscode/tasks.json     | 14 ++++++++++++++
 main.lua               | 34 ++++++++++++++++++++++++++++++++++
 shaders/particles.frag |  3 +++
 shaders/particles.vert | 14 ++++++++++++++
 4 files changed, 65 insertions(+)
 create mode 100644 .vscode/tasks.json
 create mode 100644 main.lua
 create mode 100644 shaders/particles.frag
 create mode 100644 shaders/particles.vert

diff --git a/.vscode/tasks.json b/.vscode/tasks.json
new file mode 100644
index 0000000..50ce987
--- /dev/null
+++ b/.vscode/tasks.json
@@ -0,0 +1,14 @@
+{
+    "version": "2.0.0",
+    "tasks": [
+        {
+            "label": "build",
+            "type": "shell",
+            "command": "lovr-sync",
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            }
+        }
+    ]
+}
diff --git a/main.lua b/main.lua
new file mode 100644
index 0000000..5ca544e
--- /dev/null
+++ b/main.lua
@@ -0,0 +1,34 @@
+local mat4 = lovr.math.mat4
+
+local features
+local shaders = {}
+local blocks = {}
+local meshes = {}
+
+function lovr.load()
+    features = lovr.graphics.getFeatures()
+    shaders.particles = lovr.graphics.newShader("shaders/particles.vert", "shaders/particles.frag")
+    blocks.particles = lovr.graphics.newShaderBlock("compute", {
+        particlePos = {"vec4", 1024},
+    }, { readable = true, writable = true })
+    shaders.particles:sendBlock('particleData', blocks.particles)
+    meshes.particle = lovr.graphics.newMesh(
+        {
+            {'vertPosition', 'float', 2},
+        },
+        {{1, 1}, {1, -1}, {-1, -1}, {-1, 1}},
+        "triangles", "static"
+    )
+    meshes.particle:setVertexMap({3, 2, 1, 4, 3, 1})
+end
+
+function lovr.draw()
+    lovr.graphics.clear()
+    lovr.graphics.setColor(0, 0.5, 1)
+    local x, y, z = lovr.headset.getPose("head")
+    shaders.particles:send("headPos", {x, y, z})
+
+    blocks.particles:send("particlePos", {{0, 2, -2, 0}, {-1, 1, -4, 0}})
+    lovr.graphics.setShader(shaders.particles)
+    meshes.particle:draw(mat4(), 2)
+end
diff --git a/shaders/particles.frag b/shaders/particles.frag
new file mode 100644
index 0000000..fff0f2a
--- /dev/null
+++ b/shaders/particles.frag
@@ -0,0 +1,3 @@
+vec4 color(vec4 graphicsColor, sampler2D image, vec2 uv) {
+  return graphicsColor;
+}
diff --git a/shaders/particles.vert b/shaders/particles.vert
new file mode 100644
index 0000000..3ff33f8
--- /dev/null
+++ b/shaders/particles.vert
@@ -0,0 +1,14 @@
+in vec2 vertPosition;
+uniform vec3 headPos;
+layout(std430) buffer particleData { vec4 particlePos[2]; };
+
+vec4 position(mat4 projection, mat4 transform, vec4 vertex) {
+  vec3 pos = particlePos[gl_InstanceID].xyz;
+  vec3 forward = normalize(pos - headPos);
+  vec3 right = normalize(cross(forward, vec3(0, 1, 0)));
+  vec3 up = cross(right, forward);
+  mat2 frame = mat2(up, right);
+  // vec3 vert = pos + vec3(frame * vertPosition * 0.3, 0);
+  vec3 vert = pos + vec3(vertPosition, 0);
+  return projection * transform * vec4(vert, 1);
+}
-- 
2.43.2