canvas/backend/goglbackend/shaders.go

package goglbackend

var unifiedVS = `
attribute vec2 vertex, texCoord;

uniform vec2 canvasSize;

varying vec2 v_cp, v_tc;

void main() {
    v_tc = texCoord;
	v_cp = vertex;
	vec2 glp = vertex * 2.0 / canvasSize - 1.0;
    gl_Position = vec4(glp.x, -glp.y, 0.0, 1.0);
}
`
var unifiedFS = `
#ifdef GL_ES
precision mediump float;
#endif

varying vec2 v_cp, v_tc;

uniform vec4 color;
uniform float globalAlpha;

uniform bool useLinearGradient;
uniform bool useRadialGradient;
uniform sampler2D gradient;
uniform vec2 from, dir, to;
uniform float len, radFrom, radTo;

uniform bool useImagePattern;
uniform vec2 imageSize;
uniform sampler2D image;
uniform mat3 imageTransform;
uniform vec2 repeat;

uniform bool useAlphaTex;
uniform sampler2D alphaTex;

uniform bool useImage;

bool isNaN(float v) {
  return v < 0.0 || 0.0 < v || v == 0.0 ? false : true;
}

void main() {
	vec4 col = color;

	if (useLinearGradient) {
		vec2 v = v_cp - from;
		float r = dot(v, dir) / len;
		r = clamp(r, 0.0, 1.0);
		col = texture2D(gradient, vec2(r, 0.0));
	} else if (useRadialGradient) {
		float o_a = 0.5 * sqrt(
			pow(-2.0*from.x*from.x+2.0*from.x*to.x+2.0*from.x*v_cp.x-2.0*to.x*v_cp.x-2.0*from.y*from.y+2.0*from.y*to.y+2.0*from.y*v_cp.y-2.0*to.y*v_cp.y+2.0*radFrom*radFrom-2.0*radFrom*radTo, 2.0)
			-4.0*(from.x*from.x-2.0*from.x*v_cp.x+v_cp.x*v_cp.x+from.y*from.y-2.0*from.y*v_cp.y+v_cp.y*v_cp.y-radFrom*radFrom)
			*(from.x*from.x-2.0*from.x*to.x+to.x*to.x+from.y*from.y-2.0*from.y*to.y+to.y*to.y-radFrom*radFrom+2.0*radFrom*radTo-radTo*radTo)
		);
		float o_b = (from.x*from.x-from.x*to.x-from.x*v_cp.x+to.x*v_cp.x+from.y*from.y-from.y*to.y-from.y*v_cp.y+to.y*v_cp.y-radFrom*radFrom+radFrom*radTo);
		float o_c = (from.x*from.x-2.0*from.x*to.x+to.x*to.x+from.y*from.y-2.0*from.y*to.y+to.y*to.y-radFrom*radFrom+2.0*radFrom*radTo-radTo*radTo);
		float o1 = (-o_a + o_b) / o_c;
		float o2 = (o_a + o_b) / o_c;
		if (isNaN(o1) && isNaN(o2)) {
			gl_FragColor = vec4(0.0, 0.0, 0.0, 0.0);
			return;
		}
		float o = max(o1, o2);
		o = clamp(o, 0.0, 1.0);
		col = texture2D(gradient, vec2(o, 0.0));
	} else if (useImagePattern) {
		vec3 tfpt = vec3(v_cp, 1.0) * imageTransform;
		vec2 imgpt = tfpt.xy / imageSize;
		col = texture2D(image, mod(imgpt, 1.0));
		if (imgpt.x < 0.0 || imgpt.x > 1.0) {
			col *= repeat.x;
		}
		if (imgpt.y < 0.0 || imgpt.y > 1.0) {
			col *= repeat.y;
		}
	} else if (useImage) {
		col = texture2D(image, v_tc);
	}

	if (useAlphaTex) {
		col.a *= texture2D(alphaTex, v_tc).a * globalAlpha;
	} else {
		col.a *= globalAlpha;
	}

    gl_FragColor = col;
}
`

var boxVS = `
attribute vec2 vertex, texCoord;

uniform vec2 canvasSize;

varying vec2 v_cp, v_tc;

void main() {
    v_tc = texCoord;
	v_cp = vertex;
	vec2 glp = vertex * 2.0 / canvasSize - 1.0;
    gl_Position = vec4(glp.x, -glp.y, 0.0, 1.0);
}
`
var boxFS = `
#ifdef GL_ES
precision mediump float;
#endif

varying vec2 v_cp, v_tc;

uniform int boxSize;
uniform bool boxVertical;
uniform float boxScale;
uniform sampler2D image;

void main() {
	vec4 color = vec4(0.0, 0.0, 0.0, 0.0);

	vec4 sum = vec4(0.0);
	if (boxVertical) {
		vec2 start = v_tc - vec2(0.0, (float)(boxSize) * boxScale);
		for (int i=0; i<boxSize*2; i++) {
			sum += texture2D(image, start + vec2(0.0, (float)(i) * boxScale));
		}
	} else {
		vec2 start = v_tc - vec2((float)(boxSize) * boxScale, 0.0);
		for (int i=0; i<boxSize*2; i++) {
			sum += texture2D(image, start + vec2((float)(i) * boxScale, 0.0));
		}
	}
	color = sum / float(boxSize * 2);

	gl_FragColor = color;
}
`

type unifiedShader struct {
	shaderProgram

	Vertex   uint32
	TexCoord uint32

	CanvasSize  int32
	Color       int32
	GlobalAlpha int32

	UseAlphaTex int32
	AlphaTex    int32

	UseLinearGradient int32
	UseRadialGradient int32
	Gradient          int32
	From, To, Dir     int32
	Len               int32
	RadFrom, RadTo    int32

	UseImagePattern int32
	ImageSize       int32
	Image           int32
	ImageTransform  int32
	Repeat          int32

	UseImage int32
}

type boxBlurShader struct {
	shaderProgram
	Vertex      uint32
	TexCoord    uint32
	CanvasSize  int32
	BoxSize     int32
	BoxVertical int32
	BoxScale    int32
	Image       int32
}