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path: root/src/libjin/render/jsl.cpp
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#include "../utils/macros.h"
#include "jsl.h"
namespace jin
{
namespace render
{
    //vec4 effect(vec4 color, Image texture, vec2 texture_coords, vec2 screen_coords) 
    static const char* base_f = " "
        "#version 120              \n"
        "#define number float      \n"
        "#define Image sampler2D   \n"
        "#define Texel texture2D   \n"
		"#define Color vec4        \n"
        "#define extern uniform    \n"
        "uniform Image _tex0_; \n"
        "%s                        \n"
        "void main(){              \n"
        "gl_FragColor = effect(gl_Color, _tex0_, gl_TexCoord[0].xy, gl_FragCoord.xy);\n"
        "}\0";

	shared GLint JSLProgram::current_texture_unit = 0;
	shared GLint JSLProgram::max_texture_units = 0;

	shared JSLProgram* JSLProgram::current_JSL_program = nullptr; 

    void JSLProgram::init(const char* program)
    {
		if(max_texture_units == 0)
			glGetIntegerv(GL_MAX_TEXTURE_IMAGE_UNITS, &max_texture_units);

        char* fs = (char*)alloca(strlen(program) + strlen(base_f));
        sprintf(fs, base_f, program);
        GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
        glShaderSource(fragmentShader, 1, (const GLchar**)&fs, NULL);
        glCompileShader(fragmentShader);

        pid = glCreateProgram();
        glAttachShader(pid, fragmentShader);
        glLinkProgram(pid);
    }

    shared GLint JSLProgram::getTextureUnit(const std::string& name)
    {
		if (++current_texture_unit >= max_texture_units)
		    return 0;
		return current_texture_unit;
    }

    void JSLProgram::use()
    {
        glUseProgram(pid); 
		JSLProgram::current_JSL_program = this;
		JSLProgram::current_texture_unit = 0;
    }

    shared void JSLProgram::unuse()
    {
        glUseProgram(0);
		JSLProgram::current_JSL_program = nullptr;
		JSLProgram::current_texture_unit = 0;
    }

#define checkJSL() if (current_JSL_program != this) return

    void JSLProgram::sendFloat(const char* variable, float number)
    {
		checkJSL();

        int loc = glGetUniformLocation(pid, variable); 
        glUniform1f(loc, number);
    }

    void JSLProgram::sendImage(const char* variable, const Image* image)
    {
		checkJSL();

        GLint texture_unit = JSLProgram::getTextureUnit(variable);

        GLint location = glGetUniformLocation(pid, variable);
		glUniform1i(location, texture_unit);

        glActiveTexture(GL_TEXTURE0 + texture_unit);
        glBindTexture(GL_TEXTURE_2D, image->getTexture()); 

        glActiveTexture(GL_TEXTURE0);
    }

	void JSLProgram::sendCanvas(const char* variable, const Canvas* canvas)
	{
		checkJSL();

		GLint texture_unit = getTextureUnit(variable);

		GLint location = glGetUniformLocation(pid, variable);
		glUniform1i(location, texture_unit);

		glActiveTexture(GL_TEXTURE0 + texture_unit);
		glBindTexture(GL_TEXTURE_2D, canvas->getTexture());

		glActiveTexture(GL_TEXTURE0);
	}

	void JSLProgram::sendVec2(const char* name, float x, float y)
	{
		checkJSL();

		int loc = glGetUniformLocation(pid, name);
		glUniform2f(loc, x, y);
	}

	void JSLProgram::sendVec3(const char* name, float x, float y, float z)
	{
		checkJSL();

		int loc = glGetUniformLocation(pid, name);
		glUniform3f(loc, x, y, z);
	}

	void JSLProgram::sendVec4(const char* name, float x, float y, float z, float w)
	{
		checkJSL();

		int loc = glGetUniformLocation(pid, name);
		glUniform4f(loc, x, y, z, w);
	}
    
	void JSLProgram::sendColor(const char* name, const color* col) 
	{
		checkJSL();

		int loc = glGetUniformLocation(pid, name);
		glUniform4f(loc,
			col->rgba.r / 255.f,
			col->rgba.g / 255.f,
			col->rgba.b / 255.f,
			col->rgba.a / 255.f
		);
	}

}
}