Lights without geometry shader (#2716)

Author: einarf

arcade/future/light/lights.py

@@ -97,18 +97,36 @@ def __init__(self, width: int, height: int):
         self._rebuild = False
         self._stride = 28
         self._buffer = self.ctx.buffer(reserve=self._stride * 100)
+        # fmt: off
+        vertex_data = array('f', [
+            -1.0, +1.0, 0.0, 1.0,
+            -1.0, -1.0, 0.0, 0.0,
+            +1.0, +1.0, 1.0, 1.0,
+            +1.0, -1.0, 1.0, 0.0,
+        ])
+        # fmt: on
         self._vao = self.ctx.geometry(
             [
+                gl.BufferDescription(
+                    self.ctx.buffer(data=vertex_data),
+                    "2f 2f",
+                    ["in_vert", "in_uv"],
+                ),
                 gl.BufferDescription(
                     self._buffer,
                     "2f 1f 1f 3f",
-                    ["in_vert", "in_radius", "in_attenuation", "in_color"],
+                    [
+                        "in_instance_position",
+                        "in_instance_radius",
+                        "in_instance_attenuation",
+                        "in_instance_color",
+                    ],
+                    instanced=True,
                 ),
             ]
         )
         self._light_program = self.ctx.load_program(
             vertex_shader=":system:shaders/lights/point_lights_vs.glsl",
-            geometry_shader=":system:shaders/lights/point_lights_geo.glsl",
             fragment_shader=":system:shaders/lights/point_lights_fs.glsl",
         )
         self._combine_program = self.ctx.load_program(
@@ -214,10 +232,12 @@ def draw(
         self._light_buffer.use()
         self._light_buffer.clear()
         if len(self._lights) > 0:
-            self._light_program["position"] = position
+            self._light_program["offset"] = position
             self.ctx.enable(self.ctx.BLEND)
             self.ctx.blend_func = self.ctx.BLEND_ADDITIVE
-            self._vao.render(self._light_program, mode=self.ctx.POINTS, vertices=len(self._lights))
+            self._vao.render(
+                self._light_program, mode=self.ctx.TRIANGLE_STRIP, instances=len(self._lights)
+            )
             self.ctx.blend_func = self.ctx.BLEND_DEFAULT
 
         # Combine pass

arcade/resources/system/shaders/lights/point_lights_fs.glsl

@@ -1,7 +1,7 @@
 #version 330
 
-
 out vec4 f_color;
+
 in vec2 uv;
 in float attenuation;
 in vec3 color;

arcade/resources/system/shaders/lights/point_lights_geo.glsl

@@ -1,17 +1,28 @@
 #version 330
 
+uniform WindowBlock {
+    mat4 projection;
+    mat4 view;
+} window;
+
+uniform vec2 offset;
+
 in vec2 in_vert;
-in float in_radius;
-in float in_attenuation;
-in vec3 in_color;
+in vec2 in_uv;
+
+in vec2 in_instance_position;
+in float in_instance_radius;
+in float in_instance_attenuation;
+in vec3 in_instance_color;
 
-out float vs_radius;
-out float vs_attenuation;
-out vec3 vs_color;
+out float attenuation;
+out vec3 color;
+out vec2 uv;
 
 void main() {
-    gl_Position = vec4(in_vert, 0.0, 1.0);
-    vs_radius = in_radius;
-    vs_attenuation = in_attenuation;
-    vs_color = in_color / 255.0;
+    vec2 position = (in_vert * in_instance_radius) + in_instance_position + offset;
+    gl_Position = window.projection * window.view * vec4(position, 0.0, 1.0);
+    uv = in_uv;
+    attenuation = in_instance_attenuation;
+    color = in_instance_color / 255.0;
 }