glTexGen_Convert.rb

#
# Simple script - Print out pseudo-code for glTexGen* states
#
# Author: James Urquhart, jamesu@gmail.com
#
# Put your code in the doCode at the end of the file.
#
require 'json'

GL_TEXTURE_2D = 1

GL_TEXTURE_ENV = :texture_env
GL_TEXTURE_ENV_MODE = :texture_env_mode
GL_COMBINE_RGB = :combine_rgb
GL_SOURCE0_RGB = :source0_rgb
GL_OPERAND0_RGB = :operand0_rgb
GL_COMBINE_ALPHA = :combine_alpha
GL_SOURCE0_ALPHA = :source0_alpha
GL_OPERAND0_ALPHA = :operand0_alpha
GL_TEXTURE_ENV_COLOR = :texture_env_color
GL_SOURCE1_ALPHA = :source1_alpha
GL_OPERAND1_ALPHA = :operand1_alpha
GL_SOURCE2_ALPHA = :source2_alpha
GL_OPERAND2_ALPHA = :operand2_alpha
GL_SOURCE1_RGB = :source1_rgb
GL_OPERAND1_RGB = :operand1_rgb
GL_SOURCE2_RGB = :source2_rgb
GL_OPERAND2_RGB = :operand2_rgb

GL_COMBINE = :combine
GL_REPLACE = :replace
GL_PREVIOUS = :previous
GL_SRC_COLOR = :src_color
GL_INTERPOLATE = :interpolate
GL_CONSTANT = :constant
GL_SRC_ALPHA = :src_alpha
GL_TEXTURE = :texture
GL_RGB_SCALE = :rgb_scale
GL_ALPHA_SCALE = :alpha_scale
GL_MODULATE = :modulate
GL_DECAL = :decal
GL_ADD = :add
GL_PRIMARY_COLOR = :primary_color


$units = []
$active_unit = nil

def glActiveTextureARB(unit)
	if unit >= $units.count
		diff = ((unit+1) - $units.count)
		diff.times { $units << {
			GL_OPERAND0_RGB => GL_SRC_COLOR,
			GL_OPERAND1_RGB => GL_SRC_COLOR,
			GL_OPERAND2_RGB => GL_SRC_COLOR,
			GL_OPERAND0_ALPHA => GL_SRC_ALPHA,
			GL_OPERAND1_ALPHA => GL_SRC_ALPHA,
			GL_OPERAND2_ALPHA => GL_SRC_ALPHA,
		} }
	end

	$active_unit = $units[unit]
end

def glTexEnvi(mode, param, value)
	$active_unit[param] = value
end

def glTexEnvf(mode, param, value)
	$active_unit[param] = value
end

def glTexEnvfv(mode, param, values)
	$active_unit[param] = values
end

def glEnable(mode)
	if mode == GL_TEXTURE_2D
		$active_unit[:textured] = true
	end
end

def glDisable(mode)
	if mode == GL_TEXTURE_2D
		$active_unit[:textured] = false
	end
end


def operandRemap(source, operand)
	case operand
	when GL_SRC_COLOR
		"#{source}.rgb"
	when GL_SRC_ALPHA
		"#{source}.a"
	else
		raise Exception.new("Unhandled operand #{operand}")
	end
end

def wrapUpAndPrint
	puts "// JSON Info"
	puts JSON.pretty_generate($units)

	puts "// Pseudo-code"
	$units.each_with_index do |unit, index|

		puts "// Unit #{index}"
		arg0 = unit[:textured] ? "sampler#{index}.sample(tex#{index}, in.uv#{index})": 'float1(1,1,1,1)'
		arg1 = "vertCol"

		if unit[GL_TEXTURE_ENV_MODE] == GL_COMBINE

			rgbCombine = unit[GL_COMBINE_RGB]
			alphaCombine = unit[GL_COMBINE_ALPHA]

			if unit[GL_SOURCE0_RGB] == GL_TEXTURE ||
				unit[GL_SOURCE1_RGB] == GL_TEXTURE ||
				unit[GL_SOURCE1_RGB] == GL_TEXTURE ||
				unit[GL_SOURCE0_ALPHA] == GL_TEXTURE ||
				unit[GL_SOURCE1_ALPHA] == GL_TEXTURE ||
				unit[GL_SOURCE2_ALPHA] == GL_TEXTURE
				puts "texture = #{arg0};"
			end

			arg0 = operandRemap(unit[GL_SOURCE0_RGB], unit[GL_OPERAND0_RGB])
			arg1 = operandRemap(unit[GL_SOURCE1_RGB], unit[GL_OPERAND1_RGB])
			arg2 = operandRemap(unit[GL_SOURCE2_RGB], unit[GL_OPERAND2_RGB])

			case rgbCombine
			when GL_REPLACE
				puts "combine.rgb = #{arg0}; // replace" 
			when GL_MODULATE
				puts "combine.rgb = #{arg0} * #{arg1}; // modulate" 
			when GL_INTERPOLATE
				puts "combine.rgb = (#{arg0} * #{arg2}) + (#{arg1} * (1.0 - #{arg2})); // interpolate" 
			end

			arg0 = operandRemap(unit[GL_SOURCE0_ALPHA], unit[GL_OPERAND0_ALPHA])
			arg1 = operandRemap(unit[GL_SOURCE1_ALPHA], unit[GL_OPERAND1_ALPHA])
			arg2 = operandRemap(unit[GL_SOURCE2_ALPHA], unit[GL_OPERAND2_ALPHA])

			case alphaCombine
			when GL_REPLACE
				puts "combine.a = #{arg0}; // replace" 
			when GL_MODULATE
				puts "combine.a = #{arg0} * #{arg2}; // modulate" 
			when GL_INTERPOLATE
				puts "combine.a = (#{arg0} * #{arg2}) + (#{arg1} * (1.0 - #{arg2})); // interpolate" 
			end

			if !unit[GL_RGB_SCALE].nil? && (unit[GL_RGB_SCALE] != 1.0)
				puts "previous.rgb = saturate(combine.rgb * #{unit[GL_RGB_SCALE]});"
			else
				puts "previous.rgb = combine.rgb;"
			end

			if !unit[GL_ALPHA_SCALE].nil? && (unit[GL_ALPHA_SCALE] != 1.0)
				puts "previous.a = saturate(combine.a * #{unit[GL_ALPHA_SCALE]});"
			else
				puts "previous.a = combine.a;"
			end

		elsif unit[GL_TEXTURE_ENV_MODE] == GL_REPLACE
			puts "previous = #{arg0}"
			if !unit[GL_RGB_SCALE].nil? && (unit[GL_RGB_SCALE] != 1.0)
				puts "previous.rgb = saturate(previous.rgb * #{unit[GL_RGB_SCALE]});"
			end
			if !unit[GL_ALPHA_SCALE].nil? && (unit[GL_ALPHA_SCALE] != 1.0)
				puts "previous.a = saturate(previous.a * #{unit[GL_ALPHA_SCALE]});"
			end

		elsif unit[GL_TEXTURE_ENV_MODE] == GL_MODULATE

			puts "modulate = #{arg0} * #{arg1};" 

			if !unit[GL_RGB_SCALE].nil? && (unit[GL_RGB_SCALE] != 1.0)
				puts "previous.rgb = saturate(modulate.rgb * #{unit[GL_RGB_SCALE]});"
			else
				puts "previous.rgb = modulate.rgb;"
			end

			if !unit[GL_ALPHA_SCALE].nil? && (unit[GL_ALPHA_SCALE] != 1.0)
				puts "previous.a = saturate(modulate.a * #{unit[GL_ALPHA_SCALE]});"
			else
				puts "previous.a = modulate.a;"
			end

		elsif unit[GL_TEXTURE_ENV_MODE] == GL_DECAL

			arg1 = 'previous'

			if !unit[GL_RGB_SCALE].nil? && (unit[GL_RGB_SCALE] != 1.0)
				puts "previous = saturate(float4((#{arg0}.rgb * #{arg0}.a) + (#{arg1}.rgb * (1.0f - #{arg0}.a)), #{arg1}.a) * unit[GL_RGB_SCALE]);"
			else
				puts "previous = float4((#{arg0}.rgb * #{arg0}.a) + (#{arg1}.rgb * (1.0f - #{arg0}.a)), #{arg1}.a);"
			end

		else
			raise Exception.new("Unhandled #{unit[GL_TEXTURE_ENV_MODE]}")
		end
	end
end


def doCode

	glActiveTextureARB(0)

	glEnable(GL_TEXTURE_2D)
	glTexEnvi(GL_TEXTURE_ENV,GL_TEXTURE_ENV_MODE,GL_COMBINE);
	glTexEnvi(GL_TEXTURE_ENV,GL_COMBINE_RGB,GL_REPLACE);
	glTexEnvi(GL_TEXTURE_ENV,GL_SOURCE0_RGB,GL_PREVIOUS);
	glTexEnvi(GL_TEXTURE_ENV,GL_OPERAND0_RGB,GL_SRC_COLOR);
	glTexEnvi(GL_TEXTURE_ENV,GL_COMBINE_ALPHA,GL_INTERPOLATE);
	glTexEnvi(GL_TEXTURE_ENV,GL_SOURCE0_ALPHA,GL_CONSTANT);
	glTexEnvi(GL_TEXTURE_ENV,GL_OPERAND0_ALPHA,GL_SRC_ALPHA);
	glTexEnvfv(GL_TEXTURE_ENV,GL_TEXTURE_ENV_COLOR,'float4(' + [1.0,1.0,1.0,1.0].join(',') + ')');
	glTexEnvi(GL_TEXTURE_ENV,GL_SOURCE1_ALPHA,GL_TEXTURE);
	glTexEnvi(GL_TEXTURE_ENV,GL_OPERAND1_ALPHA,GL_SRC_ALPHA);
	glTexEnvi(GL_TEXTURE_ENV,GL_SOURCE2_ALPHA,GL_PREVIOUS);
	glTexEnvi(GL_TEXTURE_ENV,GL_OPERAND2_ALPHA,GL_SRC_ALPHA)
end


doCode
wrapUpAndPrint