ported the University CGI demo from WINDOWS + GLUT + GLEW + GLU + OpenGL 4 to LINUX WAYLAND + EGL + GLES 2 with minimal cuts

GL_STUFF/SOURCES/EFFECTS/TexMerger.cpp

@@ -0,0 +1,134 @@
+#include "../../HEADERS/EFFECTS/TexMerger.h"
+#include "../../HEADERS/UTILS/ShaderMaker.h"
+#include <string>
+#include <iostream>
+
+#include <glm/glm.hpp>
+
+extern "C" {
+#include "../../GLES_3_1_compatibility.h"
+}
+
+TexMerger::TexMerger(GLuint texCount, unsigned int texWidth, unsigned int texHeight) {
+	glGenVertexArrays(1, &quadVAO);
+	glBindVertexArray(quadVAO);
+	glGenBuffers(1, &vertVBO);
+	glBindBuffer(GL_ARRAY_BUFFER, vertVBO);
+	glBufferData(GL_ARRAY_BUFFER, sizeof(quadVerts), quadVerts, GL_STATIC_DRAW);
+	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float)/**/, (void*)0);
+	glEnableVertexAttribArray(0);
+	std::string root = "C:\\Users\\BoBoBoat\\Desktop\\SCUOLA\\CGI\\GL_STUFF\\GL_STUFF\\SOURCES\\EFFECTS\\TEX_MERGER";
+	std::string vertSh = root + "\\vertexShader_merger.glsl";
+	std::string fragSh = root + "\\fragmentShader_merger.glsl";
+	program = ShaderMaker::createProgram(&vertSh[0], &fragSh[0]);
+	shaderTex1Id = glGetUniformLocation(program, "inTex1");
+	shaderTex2Id = glGetUniformLocation(program, "inTex2");
+
+	bufCount = ceil(log2((float)texCount));
+
+	mergeBuffers = (GLuint*) malloc(bufCount * sizeof(GLuint));
+	glGenFramebuffers(1, &FBO);
+	glGenTextures(bufCount, mergeBuffers);
+	for (unsigned int i = 0; i < bufCount; i++) {
+		glActiveTexture(GL_TEXTURE0 + i);
+		glBindTexture(GL_TEXTURE_2D, mergeBuffers[i]);
+		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, texWidth, texHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, 0);		//RGB o RGBA?
+		
+		usageMap.push_back(false);
+	}
+}
+
+GLuint TexMerger::reserveBuffer() {
+	unsigned int index = 0;
+	while (index < bufCount && usageMap[index]) {
+		index++;
+	}
+	if (index >= bufCount)
+		throw "TexMerger::reserveBuffer : free buffer not found";
+	return mergeBuffers[index];
+}
+
+bool TexMerger::isBuffer(GLuint number) {
+	bool found = false;
+	int index = -1;
+	while (!found && (++index < bufCount))
+		if (mergeBuffers[index] == number)
+			found = true;
+	return found;
+}
+
+void TexMerger::freeBuffer(GLuint number) {
+	bool found = false;
+	int index = -1;
+	while (!found && (++index < bufCount))
+		if (mergeBuffers[index] == number)
+			found = true;
+	if (found)
+		usageMap[index] = false;
+	else
+		throw "TexMerger::freeBuffer : index not found";
+}
+
+/*(BUFFER è in realtà un indice)
+* MERGE (START,END)
+*	if (END - START) == 0
+*		leggi la texture
+*		ritorna texture
+*	else
+*		MID = (START + END) / 2
+*		B1 = MERGE(START, MID)
+*		B2 = MERGE(MID + 1, END )
+*		scegli un BUFFER libero (bloccante)
+*		somma B1, B2 nel BUFFER
+*		sblocca tra B1 e B2 quelli che sono BUFFER
+*		ritorna BUFFER	
+*/
+
+GLuint TexMerger::merge(std::vector<GLuint> inTextures, int startIndex, int endIndex) {
+	if ((endIndex - startIndex) == 0) {
+		return inTextures[startIndex];
+	}
+	else {
+		int mid = (startIndex + endIndex) / 2;
+		GLuint buf1;
+		GLuint buf2;
+		GLuint result;
+		try{
+			buf1 = merge(inTextures, startIndex, mid);
+			buf2 = merge(inTextures, mid + 1, endIndex);
+			result = reserveBuffer();
+		}
+		catch( std::string ex){
+			std::cout << ex;
+		}
+		glBindFramebuffer(GL_DRAW_FRAMEBUFFER, FBO);
+		glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, result, 0);
+		GLenum DrawBuffers[1] = { GL_COLOR_ATTACHMENT0 };
+		
+		
+		/* commented and not available
+		glDrawBuffers(1, DrawBuffers);
+		*/
+		
+		//glClearColor(0, 0, 0, 0);
+		//glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+		glUseProgram(program);
+		glActiveTexture(GL_TEXTURE0);
+		glBindTexture(GL_TEXTURE_2D, buf1);
+		glUniform1i(shaderTex1Id, 0);
+		glActiveTexture(GL_TEXTURE1);
+		glBindTexture(GL_TEXTURE_2D, buf2);
+		glUniform1i(shaderTex2Id, 1);
+		glBindVertexArray(quadVAO);
+		glDrawArrays(GL_TRIANGLES, 0, 6);
+		glBindVertexArray(0);
+		if (isBuffer(buf1))
+			freeBuffer(buf1);
+		if (isBuffer(buf2))
+			freeBuffer(buf2);
+		return result;
+	}
+}