Util.cpp

#include "Util.h"
#define STB_IMAGE_IMPLEMENTATION
#include <SDL_image.h>
#include "stb_image.h"

GLuint Util::LoadTexture(const char* filePath) {
	int w, h, n;
	unsigned char* image = stbi_load(filePath, &w, &h, &n, STBI_rgb_alpha);

	if (image == NULL) {
		std::cout << "Unable to load image. Make sure the path is correct\n";
		assert(false);
	}

	GLuint textureID;
	glGenTextures(1, &textureID);
	glBindTexture(GL_TEXTURE_2D, textureID);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, image);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

	stbi_image_free(image);
	return textureID;
}

void Util::DrawText(ShaderProgram* program, GLuint fontTexture, std::string text, float size,
	float spacing, glm::vec3 position) {
	float width = 1.0f / 16.0f;
	float height = 1.0 / 16.0f;

	std::vector<float> vertices;
	std::vector<float> texCoords;

	for (int i = 0; i < text.size(); i++) {

		int index = (int)text[i];

		float u = (float)(index % 16) / 16.0f;
		float v = (float)(index / 16) / 16.0f;

		float offset = (size + spacing) * i;

		texCoords.insert(texCoords.end(), {
		u, v,
		u, v + height,
		u + width, v,
		u + width, v + height,
		u + width, v,
		u, v + height,
			});
		vertices.insert(vertices.end(), {
		 offset + (-0.5f * size), 0.5f * size,
		offset + (-0.5f * size), -0.5f * size,
		offset + (0.5f * size), 0.5f * size,
		offset + (0.5f * size), -0.5f * size,
		offset + (0.5f * size), 0.5f * size,
		offset + (-0.5f * size), -0.5f * size,
			});
	}
	glm::mat4 modelMatrix = glm::mat4(1.0f);
	modelMatrix = glm::translate(modelMatrix, position);
	program->SetModelMatrix(modelMatrix);

	glUseProgram(program->programID);

	glVertexAttribPointer(program->positionAttribute, 2, GL_FLOAT, false, 0, vertices.data());
	glEnableVertexAttribArray(program->positionAttribute);

	glVertexAttribPointer(program->texCoordAttribute, 2, GL_FLOAT, false, 0, texCoords.data());
	glEnableVertexAttribArray(program->texCoordAttribute);

	glBindTexture(GL_TEXTURE_2D, fontTexture);
	glDrawArrays(GL_TRIANGLES, 0, (int)(text.size() * 6));

	glDisableVertexAttribArray(program->positionAttribute);
	glDisableVertexAttribArray(program->texCoordAttribute);
}