WIP: adding texturing

Author: Ravenwater

CMakeLists.txt

@@ -6,8 +6,10 @@ find_package(OpenGL REQUIRED)
 
 add_executable(${PROGRAM_NAME} 
 	src/glad.c
+	src/stb_image.cpp
 	src/shader.cpp
 	src/triangle_mesh.cpp
+	src/material.cpp
 	src/main.cpp)
 
 target_include_directories(${PROGRAM_NAME} PRIVATE include)

img/checker-pattern-diagonal.jpg

@@ -3,6 +3,7 @@
 #include <glad/glad.h>
 #include <GLFW/glfw3.h>
 #include "shader.hpp"
+#include "material.hpp"
 #include "triangle_mesh.hpp"
 
 
@@ -34,12 +35,25 @@ try {
 	glViewport(0, 0, w, h);
 
 	TriangleMesh* triangle = new TriangleMesh();
+	Material* material = new Material("../img/checker-pattern-horizontal.png");
+	//Material* material = new Material("../img/checker-pattern-diagonal.jpg");
+	//Material* material = new Material("../img/marika_matsumoto.jpg");
+	Material* mask = new Material("../img/mask.jpg");
 
 	unsigned int shader = make_shader(
 		"../src/shaders/vertex.glsl",
 		"../src/shaders/fragment.glsl"
 	);
 
+	// set the texture units
+	glUseProgram(shader);
+	glUniform1i(glGetUniformLocation(shader, "material"), 0);
+	glUniform1i(glGetUniformLocation(shader, "mask"), 1);
+
+	// enable alpha blending
+	glEnable(GL_BLEND);
+	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
 	while (!glfwWindowShouldClose(window)) {
 
 		glfwPollEvents();
@@ -48,6 +62,8 @@ try {
 
 		glUseProgram(shader);
 
+		material->use(0);
+		mask->use(1);
 		triangle->draw();
 
 		glfwSwapBuffers(window);
@@ -57,6 +73,8 @@ try {
 	glDeleteProgram(shader);
 
 	delete triangle;
+	delete material;
+	delete mask;
 
 	glfwTerminate();
 

img/checker-pattern-horizontal.png

@@ -0,0 +1,48 @@
+#include <iostream>
+#include <glad/glad.h>
+#include <GLFW/glfw3.h>
+#define STB_IMAGE_IMPLEMENTATION
+#include <stb/stb_image.h>
+#include "material.hpp"
+
+Material::Material(const char* filename) {
+	int width, height, nrChannels;
+	unsigned char* data = stbi_load(filename, &width, &height, &nrChannels, STBI_rgb_alpha);
+	if (data == NULL) {
+		std::cerr << "Failed to load texture " << filename << std::endl;
+		return;
+	}
+	else {
+		std::cout << "Loaded texture " << filename << " with width " << width << " and height " << height << " nrChannels " << nrChannels << '\n';
+	}
+
+	// make the texture
+	glGenTextures(1, &texture);
+	glBindTexture(GL_TEXTURE_2D, texture);
+
+	// upload the texture
+	glTexImage2D(GL_TEXTURE_2D, 
+		0 /* MIPMAP level */, 
+		GL_RGBA, 
+		width, height, 
+		0 /* border color = black */, 
+		GL_RGBA, GL_UNSIGNED_BYTE, data);
+
+	// once uploaded, we can get rid of the data
+	stbi_image_free(data);
+
+	// configure the texture sampler
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);  // when shrinking no interpolation
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);  // when magnifying linear interpolation
+}
+
+Material::~Material() {
+	glDeleteTextures(1, &texture);
+}
+
+void Material::use(int textureUnit) {
+	glActiveTexture(GL_TEXTURE0 + textureUnit);
+	glBindTexture(GL_TEXTURE_2D, texture);
+}

img/marika_matsumoto.jpg

@@ -0,0 +1,13 @@
+#pragma once
+
+class Material {
+public:
+    Material(const char* filename);
+    ~Material();
+
+    void use(int textureUnit);
+
+private:
+    unsigned int texture;
+    unsigned int shader;
+};

img/mask.jpg

@@ -1,9 +1,23 @@
 #version 330 core
 
 in vec3 fragmentColor;
+in vec2 fragmentTextureCoord;
 
 out vec4 screenColor;
 
+uniform sampler2D material;  // texture unit 0
+uniform sampler2D mask;      // texture unit 1
+
 void main() {
-    screenColor = vec4(fragmentColor, 1.0);
+    // just color without a texture
+	//screenColor = vec4(fragmentColor, 1.0);
+	
+	// drawing a texture
+	//screenColor = texture(material, fragmentTextureCoord);
+	
+	// with a mask
+	vec3 baseColor = texture(material, fragmentTextureCoord).rgb;
+	float alpha = texture(mask, fragmentTextureCoord).r;
+	screenColor = vec4(baseColor, alpha);
+
 }