learning shading

main.lua

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+LOGLEVEL = 2
+
+
+
+-- severity levels:
+-- 0 DEBUG
+-- 1 GEN
+-- 2 ERR
+-- 3 CRIT
+
+local pixelcode = [[
+	extern number w;
+	extern number h;
+	extern number lum;
+	extern vec2 mouse;
+	vec4 effect( vec4 color, Image tex, vec2 texture_coords, vec2 screen_coords )
+	{
+		float r = screen_coords.x/w;
+		float g = screen_coords.y/h;
+		float b = (r + g) / 2;
+		float a = 1 - distance(screen_coords, mouse)/ (lum) ;
+		color = vec4(r, g, b, a+0.5);
+		return Texel(tex, texture_coords) * color;
+	}
+]]
+
+
+local vertexcode = [[
+	vec4 position( mat4 transform_projection, vec4 vertex_position )
+	{
+		return transform_projection * vertex_position;
+	}
+]]
+
+w = 1
+h = 1
+lum = 50
+t = 0
+
+function log(message, severity)
+	severity = severity or 0;
+	if severity >= LOGLEVEL then
+		print(message)
+	end
+end
+
+
+
+
+function love.load()
+
+	shader = love.graphics.newShader(pixelcode, vertexcode)
+	
+	h = love.graphics.getHeight( )
+	w = love.graphics.getWidth( )
+end
+
+
+function love.update(dt)
+	t = t + dt
+	mouse_x, mouse_y = love.mouse.getPosition( )
+	log("mouse x " .. mouse_x)
+	log("mouse y " .. mouse_y)
+	shader:send("w", w)
+	shader:send("h", h)
+	shader:send("mouse", {mouse_x, mouse_y})
+	shader:send("lum", lum)
+	log("dt = " .. dt)
+	if love.keyboard.isDown('space') then
+		lum = lum + 1
+	elseif love.keyboard.isDown('rctrl') then
+		lum = lum - 1
+	elseif love.keyboard.isDown('lctrl') then
+		lum = lum -1
+  	end
+end
+
+
+function love.draw(dt)
+	love.graphics.setShader(shader)
+    love.graphics.rectangle("fill", 0, 0, w, h)
+	love.graphics.setShader()
+    love.graphics.rectangle("fill", 400, 400, 100, 100)
+
+end
+
+

readme.md

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+#