Custom Shader Examples

Parent: Writing Custom Shaders

A Grey Shader

The code below defines a Grey shader consisting of:

• mycshaders/vShaderGrey.glsl vertex shader
• mycshaders/fShaderGrey.glsl fragment shader

Here the shader files are in the assets/mycshaders directory.

GLSL Vertex Shader: mycshaders/vShaderGrey.glsl

uniform highp mat4 vMatrix;
attribute highp vec3 vVertex;
attribute mediump vec2 vTexCoord;
varying mediump vec2 fTexCoord;

void main() {
	vec4 vertex = vec4(vVertex, 0.8); // vertex coords, scale
	gl_Position = vMatrix*vertex;
	fTexCoord = vTexCoord;
}

GLSL Fragment Shader: mycshaders/fShaderGrey.glsl

//precision highp float;
#ifdef GLES2
	precision highp float;
#endif
uniform lowp vec4 fColor;
uniform lowp sampler2D fTexture;
varying mediump vec2 fTexCoord;
 
void main() {
	lowp vec4 frag = fColor*texture2D(fTexture, fTexCoord);
	float color;
	if (frag.a == 0.0) {
		gl_FragColor = vec4(1.0, 0.5, 1.0, 1.0); // purple
	} else {
		color = dot(frag.rgb, vec3(0.299, 0.587, 0.114));
		gl_FragColor = vec4(color, color, color, frag.a); // gray
	}
}

Lua Code

-- open gl shader
local shadergrey = Shader.new("mycshaders/vShaderGrey", "mycshaders/fShaderGrey", 0,
	{
	{name="vMatrix", type=Shader.CMATRIX, sys=Shader.SYS_WVP, vertex=true},
	{name="fColor", type=Shader.CFLOAT4, sys=Shader.SYS_COLOR, vertex=false},
	{name="fTexture", type=Shader.CTEXTURE, vertex=false},
	},
	{
	{name="vVertex", type=Shader.DFLOAT, mult=3, slot=0, offset=0},
	{name="vColor", type=Shader.DUBYTE, mult=4, slot=1, offset=0},
	{name="vTexCoord", type=Shader.DFLOAT, mult=2, slot=2, offset=0},
	}
)

application:setBackgroundColor(0x333333)

local bitmap = Bitmap.new(Texture.new("gfx/test.png"))
local bitmap2 = Bitmap.new(Texture.new("gfx/arrow_0001.png"))
-- position
bitmap:setPosition(32*1, 32*4)
bitmap2:setPosition(32*6, 32*1)
-- shaders
bitmap:setShader(shadergrey)
bitmap2:setShader(shadergrey)
-- order
stage:addChild(bitmap)
stage:addChild(bitmap2)

A Wave Shader

The code below defines a Wave shader consisting of:

• mycshaders/vShaderWave.glsl vertex shader
• mycshaders/fShaderWave.glsl fragment shader

Here the shader files are in the assets/mycshaders directory.

GLSL Vertex Shader: mycshaders/vShaderWave.glsl

attribute vec4 POSITION0;
attribute vec2 TEXCOORD0;
uniform mat4 g_MVPMatrix;
varying vec2 texCoord;

void main()
{
	gl_Position = g_MVPMatrix * POSITION0;
	texCoord = TEXCOORD0;
}

GLSL Fragment Shader: mycshaders/fShaderWave.glsl

uniform lowp sampler2D g_Texture;
uniform lowp vec4 g_Color;
uniform highp float time;
varying highp vec2 texCoord;

void main()
{
	highp vec2 tc = texCoord.xy;
//	highp float dist = cos(tc.x * 24.0 - time * 4.0) * 0.02;
	highp float dist = cos(tc.x * 2.0 - time * 8.0) * 0.02;
	highp vec2 uv = tc + dist;
	gl_FragColor = g_Color * texture2D(g_Texture, uv);
}

Lua Code

-- open gl shader
local shaderwave = Shader.new("mycshaders/vShaderWave", "mycshaders/fShaderWave", 0,
	{
	{name="g_MVPMatrix", type=Shader.CMATRIX, sys=Shader.SYS_WVP, vertex=true},
	{name="g_Color", type=Shader.CFLOAT4, mult=1, sys=Shader.SYS_COLOR},
	{name="g_Texture", type=Shader.CTEXTURE, mult=1, vertex=false},
	{name="time", type=Shader.CFLOAT, mult=1, vertex=false}
	},
	{
	{name="POSITION0", type=Shader.DFLOAT, mult=3, slot=0, offset=0},
	{name="vColor", type=Shader.DUBYTE, mult=0, slot=1, offset=0},
	{name="TEXCOORD0", type=Shader.DFLOAT, mult=2, slot=2, offset=0}
	}
)

application:setBackgroundColor(0x333333)

local bitmap = Bitmap.new(Texture.new("gfx/test.png"))
local bitmap2 = bitmap:clone()
-- position
bitmap:setPosition(32*1, 32*4)
bitmap2:setPosition(32*6, 32*1)
-- shaders
bitmap:setShader(shaderwave)
bitmap2:setShader(shaderwave)
-- order
stage:addChild(bitmap)
stage:addChild(bitmap2)

-- loop
local timer = 0
stage:addEventListener(Event.ENTER_FRAME, function(e)
	timer += 0.018
	shaderwave:setConstant("time", Shader.CFLOAT, 1, timer)
	bitmap:setX(bitmap:getX() + 1)
	if bitmap:getX() > 400 then bitmap:setX(-80) end
end)

An Outline Shader from Code FLAG_FROM_CODE

spriteOutline = {}

spriteOutline.VS_GL = [[

	uniform highp mat4 vMatrix;

	attribute highp vec3 vVertex;
	attribute mediump vec2 vTexCoord;

	varying mediump vec2 fTexCoord;

	void main() {
		vec4 vertex = vec4(vVertex, 1.0);
		gl_Position = vMatrix*vertex;
		fTexCoord = vTexCoord;
	}
]]

spriteOutline.FS_GL = [[

	#ifdef GL_ES
		precision highp float;
	#endif

	const float offseta = 0.010;

	uniform lowp vec4 fColor;
	uniform mediump vec4 fTexSize;
	uniform lowp sampler2D fTexture;

	uniform lowp int fSwitch;

	varying mediump vec2 fTexCoord;

	vec4 getSample(float x, float y, float offset, float num)
	{
		vec4 result = vec4(0);
		float size = 360.0 / num;

		for (float a; a <= 360.0; a += size)
		{
			vec2 coord = vec2(cos(a) * offset + x, sin(a) * offset + y);

			result += texture2D(fTexture, coord);
		}

		return result;
	}

	void main()
	{
		vec4 col = texture2D(fTexture, fTexCoord);

		float nums = 32.0;

		if (fSwitch == 44) // fSwitch can be changed in code, 44 is some random value for documentation purposes
		{
			vec4 nb = getSample(fTexCoord.x, fTexCoord.y, 0.020, nums);

			if (col.a > 0. && nb.a < nums)
			{
				col.a = nb.a / nums;
				col.r = nb.a / nums;
				col.g = 0.0;
				col.b = 0.0;
			}
		}

		gl_FragColor = col;
	}
]]

spriteOutline.Shader=Shader.new(spriteOutline.VS_GL, spriteOutline.FS_GL, Shader.FLAG_FROM_CODE,
	{
	{name="vMatrix",type=Shader.CMATRIX,sys=Shader.SYS_WVP,vertex=true},
	{name="fColor",type=Shader.CFLOAT4,sys=Shader.SYS_COLOR,vertex=false},
	{name="fTexture",type=Shader.CTEXTURE,vertex=false},
	{name="fSwitch",type=Shader.CINT,vertex=false},
	},
	{
	{name="vVertex",type=Shader.DFLOAT,mult=3,slot=0,offset=0},
	{name="vColor",type=Shader.DUBYTE,mult=4,slot=1,offset=0},
	{name="vTexCoord",type=Shader.DFLOAT,mult=2,slot=2,offset=0},
	}
)

local sprite = Bitmap.new(Texture.new("gfx/test.png"))
--spriteOutline.Shader:setConstant("fSwitch", Shader.CINT, 1, 44) -- set fSwitch value to be 44
sprite:setShader(spriteOutline.Shader)
sprite:setShaderConstant("fSwitch", Shader.CINT, 1, 44) -- set fSwitch value to be 44
stage:addChild(sprite)

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